By Ivan G. Nassar
In 1609, Galileo Galilei, Italian Mathematician, Astronomer and Physicist, credited as the inventor of the first telescope turned his instrument to the night sky and made astounding discoveries that forever changed mankind’s understanding of the grand scale structure of the Universe. To commemorate this occasion the astronomical world has dedicated the year 2009 as The International Year of Astronomy. The International Astronomical Union (IAU) and United Nations Educational, Scientific and Cultural Organization (UNESCO) has initiated an effort to help the citizens of the world rediscover their place in the Universe. While the astronomical world is reflecting on its highlights and achievements, it is fitting that the contributions of early Islamic astronomers receive a measure of recognition for their pioneering work.
Early religious communities had little or no tolerance for findings that conflicted with the literal interpretation of church doctrines. Witness Nicolaus Copernicus, the Polish monk who proposed replacing the Ptolemaic theory which incorrectly assumed that the earth was the center of the universe and the planets revolved around it. Or consider Galileo Galilei who accepted the Copernican heliocentric design, and paid the price for his allege blasphemy of church doctrine. The inquisition in Rome forced Galileo to recant his theories and writing and he would spend the last eight years of his life under house arrest.
Centuries before Copernicus and Galileo, in 762 CE the Abbasid dynasty took over the khalifate of the vast Muslim empire and moved the capital to Baghdad. While Europe was in the grasp of dystopia, Baghdad was a flowing fountain of knowledge with an inexcusable consortium of scholars to quench the thirst for learning. Historian called this time: ‘The Golden Age of Islam’.
The most famous mathematician, Al-Khawarizmi, the “father” of algebra (named after his book “Kitab al-Jabr”). Was just one among a family of scholars residing at Baghdad’s great learning center: Bayt al-Hikmah (The House of Wisdom)
Baghdad was a thriving metropolis of museums, hospitals, libraries, and mosques. Muslim scholars translated old Greek texts. The House of Wisdom attracted strong intellectual interest, as scholars; from all over, the world came to study the works of Aristotle, Plato, Hippocrates, Euclid, and Pythagoras. Over the next five centuries, much of the knowledge in the Alexandrian tradition became the springboard to the discipline of Islamic astronomy, medicine, mathematics, chemistry, literature, and more.
One of the most important astronomers and mathematicians of this time was al-Battani (c. 858-929), whose full name was Abu Abdullah Muhammad ibn Jabir ibn Sinan al – Raqqi al – Harrani al – Sabi al – Battani. The works of Battan had a large influence on European Renaissance scientists such as Tycho Brahe, Kepler, Galileo and Copernicus. Al-Battani wrote books on astronomy and mathematics, he’s best known for his book Kitabal-Zij. This famous book included a star catalog, trigonometric tables, solar, lunar, and planetary tables. His observations exposed the errors in Ptolemy’s Almagest of the main parameters of planetary motion.
Abd-al-Rahman Al Sufi (December 7, 903 – May 25, 986 A.D.) a Persian astronomer and sometimes referred to as Azophi made several corrections to Ptolemy’s star list and he formulated his own brightness/magnitude estimates of stars which frequently departed from those in Ptolemy’s work. Al Sufi dedicated his book the constellations of The Fixed Stars. (Kitab suwar al-kawakib) to the Buwayhid ruler Fana Khusrau, titled Adud al-Dawla (made Emir of Iraq in 949 CE and died in 982 CE), who was a great patron of astronomy and had erected an observatory at Shiraz. Al Sufi was the first to assign Arabic nomenclature to stars and constellations, many of which have survived to this day and listed in modern scientific astronomical atlases. Al-Sufi, described and depicted in 964 AD an object, in the night sky known as the “little cloud.” This little cloud turned out to be The Andromeda Galaxy, frequently referred to as M 31 since it is the 31st object on Charles Messier list of diffuse sky objects, The celebrated French astronomer cataloged this object on August 3, 1764 obviously unaware of the Persian astronomer early reports, the French astronomer ascribed its discovery to Simon Marius.
The ancient Middle Eastern peoples undoubtedly had observed two fuzzy cloud-like objects easily visible in the southern hemisphere. However, the first record of it official observation was Al Sufi in 964; he called it Al Bakr, the White Ox.
European astronomers did not record this sighting til the expedition of Ferdinand Magellan. The 16th century Portuguese navigator and his crew had plenty of time to study the southern sky during the first circumnavigation of planet Earth. As a result, two fuzzy cloud-like objects are known as the Clouds of Magellan, now understood to be satellite galaxies of our much larger, spiral Milky Way galaxy.
The uniqueness of Islamic rule in Spain was tolerance of diversity. Muslims, Christians and Jews lived and worked together in an ambience of peaceful coexistence. There are substantial reports of influential Women competing professionally in the business world under Moorish rule. The Moors were a highly civilized people devoted to the pursuit of fairness and the transmission of knowledge.
The Moors produced astronomical tables with the 0-degree longitude reference in the Moorish capital of Cordoba, some 700 years before Great Britain convinced the world to establish the 0-degree reference at the Royal Observatory in Greenwich London to coordinate world time to the Greenwich Mean Time standard, also known as Greenwich meridian time (GMT).
Queen Isabella of Castile and King, Ferdinand 11 of Aragon achieved the conquest of Spain by, expelling the last ruler of the Moor’s from its Granada stronghold in 1492. The Catholic Monarchs set out to restore royal authority in Spain. This was a particularly bad time for non-Catholics as Isabella and Ferdinand began a reign of terror, for those who did not renounce their own religion and became a Catholic. The Monarch issued the following orders to the Jewish population: By July 1,1492 all people of the Jewish faith had to covert to the Catholic religion or leave Spain.
Isabella and Ferdinand are most famous for authorizing the first expedition of Christopher Columbus voyage to the Americas and bestowing upon him the name “Admiral of the Ocean Sea” . This incongruous event of Columbus voyage to the new world was finance at the price of religion freedom.
“If there is much misunderstanding in the West about the nature of Islam, there is also much ignorance about the debt our own culture and civilization owe to the Islamic world. It is a failure, which stems, I think, from the straight-jacket of history, which we have inherited. The medieval Islamic world, from central Asia to the shores of the Atlantic, was a world where scholars and men of learning flourished. But because we have tended to see Islam as the enemy of the West, as an alien culture, society, and system of belief, we have tended to ignore or erase its great relevance to our own history.” Prince Charles, lecture at Oxford University.
http://muslimmedianetwork.com
Showing posts with label Quantum Education. Show all posts
Showing posts with label Quantum Education. Show all posts
Saturday, June 27, 2009
Tuesday, June 16, 2009
The Role Of Astronomy In Islam - Part 1
Dr. Shirin Haque-Copilah
Physics Dept, Univ. of the West Indies
Introduction
“We have not created the heaven and the earth and all that is between them in mere idle play. None of this have We created without an inner truth: but most of them understand it not.” (44: 38-39)
“In the creation of the heavens and earth, and the alternation of the night and day, and the ships which sail the seas to people's benefit, and the water which Allah sends down from the sky -- by which He brings the earth to life when it was dead and scatters about in it creatures of every kind -- and the varying direction of the winds, and the clouds subservient between heaven and earth, there are signs for people who use their intellect.” (2:164)
Need more be said? One of the purposes of the Holy Qur'an's revelation is to invite people to think. What can possibly be more straightforward than that regarding our conduct here on earth with respect to the use of our intellect to understand the world around us. The holy Qur’an delves into the many signs of Allah in nature, around us and within us to convey a deep sense of awe at the many signs of our Lord, apparent to those who use intellect. It is truly remarkable that the Qur’an revealed between 610 and 632 CE contains in it, scientific knowledge that has taken centuries to be discovered. The only explanation for this is that without a doubt, it is divine in origin. We Muslims believe that the Qur’an, in original Arabic, is the actual word of Allah, the Most High. A proper understanding of the Qur’an therefore also requires an understanding of science. It is not the purpose of the Qur’an to explain science to us but it encourages persons to reflect on the works of creation so that we may realize the greatness of Almighty God. Before we delve any further, it is necessary to make clear a very important distinction – that between Astronomy and Astrology – the two terms are often confused by many persons as meaning the same. They cannot be further from each other. Astronomy is a science and halal whereas astrology is a pseudo science and haram. Astronomy deals with the study of the heavens in an effort to understand the underlying principles governing the behaviour of the planets, stars and galaxies and the Universe in general. Astrology claims to predict the destinies of persons as a result of the ‘action’ of planets and so on, on their lives. There has not been to date any contradiction between Astronomy, as we understand it, and the Qur’an.
The Qur’an deals with many areas of science such as geology of earth, the animal and vegetable kingdom, human reproduction and Astronomy. This article concentrates on the position of Astronomy in Islam with emphasis on observed facts and not theories. A theory is used to explain an observed or hypothesized phenomena and it may be modified, changed, or rejected in due course depending on how appropriate it may be against observational data. Theories can be subjective in nature. An observation is a fact and is not liable to be changed but may be further refined.
This article does not deal with speculative Astronomy. Because like all sciences, we do not understand everything and there are many things that remain as models. It should be borne in mind that a thousand experiments will not prove a theory correct but one experiment can disprove it. Understanding the underlying principles behind the clockwork of the Universe endows us with a far deeper sense of awe and appreciation of the One that created it. The sentiment is similar to that expressed by Physicist Richard Feynman:
“I have a friend who's an artist and he's sometimes taken a view which I don't agree with very well. He'll hold up a flower and say. “Look how beautiful it is,“ and I'll agree, I think. And he says - “ you see, I as an artist can see how beautiful this is, but you as a scientist, oh, take this all apart and it becomes a dull thing.“ And I think that he's kind of nutty. First of all, the beauty that he sees is available to other people and to me, too, I believe, although I might not be quite as refined aesthetically as he is, but I can appreciate the beauty of a flower. At the same time I see much more about the flower than he sees. I could imagine the cells in there, the complicated actions inside which also have a beauty. I mean it's not just beauty at this dimension of one centimeter, there is also beauty at a smaller dimension, the inner structure. Also the processes, the fact that the colors in the flower are evolved in order to attract insects to pollinate it is interesting - it means that insects can see the color. It adds a question: Does this aesthetic sense also exist in the lower form? Why is it aesthetic? All kinds of interesting questions which a science knowledge only adds to the excitement and mystery and the awe of a flower. It only adds; I don't understand how it subtracts.“ - Richard P. Feynman (1918-1988)
It not only adds, but enriches, it deepens. Understanding and developing an appreciation of creations of Allah using the tools of science can enrich and deepen a believer’s consciousness of the Creator.
If there is any religion that invites man to the study and understanding of the heavens, it is Islam. An understanding of the discipline of Astronomy is essential for the appreciation of the religion of Islam. No other religion uses or relies on the heavens and the motion of the moon and sun for timekeeping and calendars as Islam does. Allah created this tremendous Universe that we live in and we are invited to reflect upon it, to understand it so that we may be able to practise our religion with conviction based on reason to the best of our abilities. By God’s laws, the laws of Physics, we are glued to the planet earth yet Almighty God granted us eyes, intellect and knowledge that we may see far in excess of our ordinary reach- surely in these things are signs of the omnipotence of our Creator.
“Allah is He, who created the sun, the moon, and the stars (all) governed by laws under His commandment.” (7:54)
“He has made subject to you, the night and the day; the sun and the moon; and the stars in subjection by His command.” (14:33; 16:12)
Astronomy in the Qur’an
Just pause and try and imagine the Arabian night skies – crisp and clear, twinkling gently and kindly …invitingly, literally showing mankind the way. We see below a sampling of some of the mentions of Astronomy in the Qur’an. It is by no means a catalogue. The Qur’an tells us that the stars are there to guide us on land and sea.
“And it is He who ordained the stars for you that you may be guided thereby in the darkness of the land and the sea.” (6:97)
“And marks and sign-posts and by the stars, (men) guide themselves.” (16:16)
If you become familiar with the constellations and the stars in the sky, one can never be lost anywhere in the world. They are truly a guiding light in the canopy of the heavens. You can be anywhere in the world and immediately on looking up in the night sky and by recognizing stars, you can know what latitude you are at and where is north and thereby all the other directions. You can know what time of the year it is in the absence of any calendars. It is rather appropriate that the crescent moon and star is used as signs to represent matters of religion among Muslims. The moon holds a most important position for the reckoning of time among Muslims. The lunar calendar is one of the oldest and a natural calendar system and astronomers acknowledge that the Muslim calendar is the only purely lunar calendar in wide use
“They ask you about new crescent moons, say they are to mark fixed times for mankind and Hajj.” (2:189)
“And He who made the night for rest and sun and moon for reckoning of time. This is the decree of the Exalted, the All-knowing.” (6:96)
“It is He who made sun a lamp, and moon a light and measured stages so you know number of years and count (of time).” (10:5)
“And He subjected the sun and the moon (to His law); each one runs its course for a term appointed.” (13:2), (31:29), (35:13), and (39:5)
It is interesting to note that that the Qur’an refers to many heavens and earths. It is remarkable that one of the more recent discoveries in Astronomy has been that of other worlds such as ours.It was as recently as 1995 that the first planet outside of our solar system was discovered. To date several such planets have been found and extrasolar planets seem to be the rule rather than the exception. How many many aeons ago the Qur’an mentioned this!
“God is the One Who created seven heavens and of the earth a similar number. The command descends upon them so that you know that God has power over all things and comprehends all things in His knowledge.” (65:12)
The Qur’an always refers to the sun and moon differently. The sun is referred to as siraj (light) and zia (signifies that light which exists by itself) while the moon is referred to as nur – which means derived light. This is very accurate since the sun is a celestial body that gives off its own light because of nuclear processes in its interior. However the moon shines only by reflected light.
“And made the moon a light in their midst and made the sun as a (Glorious) lamp.” (71:16)
At the time of revelation of the Qur’an, it was a commonly held belief that the earth stood still and that the sun orbited around us. After all it seemed logical. Man’s ego was bigger than the universe or so he thought. It was easier to believe that he lived in the centre of the universe.
It was not until the16th century that the astronomer Copernicus showed otherwise, that the earth orbited around the sun instead. Just pause and look at the time interval when that piece of information was in the holy Qur’an. Hostility to Science generally and Astronomy particularly was the misfortune of the Catholic Church in the early 16th and 17th century. Let us not imitate them.
“It is He who created the night and the day, and the sun and the moon, all (the celestial bodies) swim along, each in its orbit.” (21:33)
“And the moon, we have measured for her mansions (to traverse) till she returns like the old, (withered, and curved-up like a sickle) date-palm. It is not permitted for sun to catch-up the moon, nor can the night outstrip the day; each swims along in (its own) orbit.” (36:39-40)
The stars adorn our night skies and endow one with a sense of peace with their gentle twinkling. The Qur’an says:
“Consider those (stars) that rise only to set. And move (in their orbits) with steady motion. And float (through space) with floating serene. And yet overtake (one another) with swift overtaking. And thus fulfil the (Creator’s) behest!” (79:1-5)
It is only on the scale of the galaxy that this verse comes to light! A galaxy is composed of millions and millions of stars. A galaxy like ours, the Milky Way is a spiral galaxy and rotates. Yes, the stars do move in an orbit and with steady motion too as they float through space. They do overtake one another because in any spiral structure that is rotating, the outer arms will move at a faster rate than the inner sections and will thereby overtake the stars on the interior in their motion. The spiral nature of our galaxy was only discovered in this century since its spiral nature is not easily evident to us as we reside inside.
There is order, cosmos…not chaos in this tremendous universe. The moon and earth float in orbits and they are predictable in their behaviour. It has been shown that if one planet was removed from our system, our solar system is no longer stable. Comets are predictable and they return as expected bound by the laws of Physics, God’s laws. Man can never truly invent, he can only discover. The Universe is predictable in its behaviour because Allah has subjugated its constituents and they obey him scrupulously, unlike man who has been granted will.
“Then He turned to the sky when it had been gas and said to it and the earth, condense willingly or unwillingly. And they said, “We condensed willingly.” (41:11)
Allah only has to say ‘Be’ and a thing is. It is important to note that present day physics cannot go back to the beginning of time but only very close to the ‘beginning’. The understanding of the physics of the universe begins at t = 10 –43 s, i.e. at 0.0000000000000000000000000000000000000000001 s. We now understand that the early universe was composed of hydrogen and helium gases and some regions were slightly colder or denser than other regions, these regions condensed to become galaxies composed off numerous stars within them. It is as recent as the 1950’s that such ideas have been explored. Yet there it is in the Qur’an as plain as daylight so many many hundreds of years ago. Even the concept of time is worthy of reflecting over. The order of a second may be comfortable to us but we have been able to use atomic clocks for timekeeping which have an accuracy of one part in 1012 .or meaning that if two Caesium clocks are operated they will differ by no more than 1 s after running for 6000 years! In these things are signs of our Lord…. Allah alone is worthy of praise!
“Consider the flight of time!” (103:1)
With respect to the expansion of the universe we find the following verse in the Qur’an:
“And the universe, we constructed with power and skill and verily we are expanding it.” (51:47)
To date all observations show that the Universe is expanding. Galaxies have been observed to be receding away from us at higher and higher speeds, the further away they are. This indicates that we live in an expanding universe. This was discovered in 1926 by Edwin Hubble. The concept of an expanding universe was so alien at the time that it owes to it the famous fudge factor by Albert Einstein. His calculations showed that the Universe should be expanding, but the concept was so bizarre that he included a constant into the equations so as to obtain a static Universe! This he modified later when Hubble observed that the Universe was expanding. It is far easier to be comfortable with the concept of a static universe than one that is expanding. Yet the Qur’an mentions even this, our expanding Universe.
“He Who created the seven heavens, one above another: No want of proportion will you see in the creation of Most Gracious, so turn your face again; Do you see any flaw ... .... And We have adorned the lowest heaven with lamps ....” (67:3-5)
Physics Dept, Univ. of the West Indies
Introduction
“We have not created the heaven and the earth and all that is between them in mere idle play. None of this have We created without an inner truth: but most of them understand it not.” (44: 38-39)
“In the creation of the heavens and earth, and the alternation of the night and day, and the ships which sail the seas to people's benefit, and the water which Allah sends down from the sky -- by which He brings the earth to life when it was dead and scatters about in it creatures of every kind -- and the varying direction of the winds, and the clouds subservient between heaven and earth, there are signs for people who use their intellect.” (2:164)
Need more be said? One of the purposes of the Holy Qur'an's revelation is to invite people to think. What can possibly be more straightforward than that regarding our conduct here on earth with respect to the use of our intellect to understand the world around us. The holy Qur’an delves into the many signs of Allah in nature, around us and within us to convey a deep sense of awe at the many signs of our Lord, apparent to those who use intellect. It is truly remarkable that the Qur’an revealed between 610 and 632 CE contains in it, scientific knowledge that has taken centuries to be discovered. The only explanation for this is that without a doubt, it is divine in origin. We Muslims believe that the Qur’an, in original Arabic, is the actual word of Allah, the Most High. A proper understanding of the Qur’an therefore also requires an understanding of science. It is not the purpose of the Qur’an to explain science to us but it encourages persons to reflect on the works of creation so that we may realize the greatness of Almighty God. Before we delve any further, it is necessary to make clear a very important distinction – that between Astronomy and Astrology – the two terms are often confused by many persons as meaning the same. They cannot be further from each other. Astronomy is a science and halal whereas astrology is a pseudo science and haram. Astronomy deals with the study of the heavens in an effort to understand the underlying principles governing the behaviour of the planets, stars and galaxies and the Universe in general. Astrology claims to predict the destinies of persons as a result of the ‘action’ of planets and so on, on their lives. There has not been to date any contradiction between Astronomy, as we understand it, and the Qur’an.
The Qur’an deals with many areas of science such as geology of earth, the animal and vegetable kingdom, human reproduction and Astronomy. This article concentrates on the position of Astronomy in Islam with emphasis on observed facts and not theories. A theory is used to explain an observed or hypothesized phenomena and it may be modified, changed, or rejected in due course depending on how appropriate it may be against observational data. Theories can be subjective in nature. An observation is a fact and is not liable to be changed but may be further refined.
This article does not deal with speculative Astronomy. Because like all sciences, we do not understand everything and there are many things that remain as models. It should be borne in mind that a thousand experiments will not prove a theory correct but one experiment can disprove it. Understanding the underlying principles behind the clockwork of the Universe endows us with a far deeper sense of awe and appreciation of the One that created it. The sentiment is similar to that expressed by Physicist Richard Feynman:
“I have a friend who's an artist and he's sometimes taken a view which I don't agree with very well. He'll hold up a flower and say. “Look how beautiful it is,“ and I'll agree, I think. And he says - “ you see, I as an artist can see how beautiful this is, but you as a scientist, oh, take this all apart and it becomes a dull thing.“ And I think that he's kind of nutty. First of all, the beauty that he sees is available to other people and to me, too, I believe, although I might not be quite as refined aesthetically as he is, but I can appreciate the beauty of a flower. At the same time I see much more about the flower than he sees. I could imagine the cells in there, the complicated actions inside which also have a beauty. I mean it's not just beauty at this dimension of one centimeter, there is also beauty at a smaller dimension, the inner structure. Also the processes, the fact that the colors in the flower are evolved in order to attract insects to pollinate it is interesting - it means that insects can see the color. It adds a question: Does this aesthetic sense also exist in the lower form? Why is it aesthetic? All kinds of interesting questions which a science knowledge only adds to the excitement and mystery and the awe of a flower. It only adds; I don't understand how it subtracts.“ - Richard P. Feynman (1918-1988)
It not only adds, but enriches, it deepens. Understanding and developing an appreciation of creations of Allah using the tools of science can enrich and deepen a believer’s consciousness of the Creator.
If there is any religion that invites man to the study and understanding of the heavens, it is Islam. An understanding of the discipline of Astronomy is essential for the appreciation of the religion of Islam. No other religion uses or relies on the heavens and the motion of the moon and sun for timekeeping and calendars as Islam does. Allah created this tremendous Universe that we live in and we are invited to reflect upon it, to understand it so that we may be able to practise our religion with conviction based on reason to the best of our abilities. By God’s laws, the laws of Physics, we are glued to the planet earth yet Almighty God granted us eyes, intellect and knowledge that we may see far in excess of our ordinary reach- surely in these things are signs of the omnipotence of our Creator.
“Allah is He, who created the sun, the moon, and the stars (all) governed by laws under His commandment.” (7:54)
“He has made subject to you, the night and the day; the sun and the moon; and the stars in subjection by His command.” (14:33; 16:12)
Astronomy in the Qur’an
Just pause and try and imagine the Arabian night skies – crisp and clear, twinkling gently and kindly …invitingly, literally showing mankind the way. We see below a sampling of some of the mentions of Astronomy in the Qur’an. It is by no means a catalogue. The Qur’an tells us that the stars are there to guide us on land and sea.
“And it is He who ordained the stars for you that you may be guided thereby in the darkness of the land and the sea.” (6:97)
“And marks and sign-posts and by the stars, (men) guide themselves.” (16:16)
If you become familiar with the constellations and the stars in the sky, one can never be lost anywhere in the world. They are truly a guiding light in the canopy of the heavens. You can be anywhere in the world and immediately on looking up in the night sky and by recognizing stars, you can know what latitude you are at and where is north and thereby all the other directions. You can know what time of the year it is in the absence of any calendars. It is rather appropriate that the crescent moon and star is used as signs to represent matters of religion among Muslims. The moon holds a most important position for the reckoning of time among Muslims. The lunar calendar is one of the oldest and a natural calendar system and astronomers acknowledge that the Muslim calendar is the only purely lunar calendar in wide use
“They ask you about new crescent moons, say they are to mark fixed times for mankind and Hajj.” (2:189)
“And He who made the night for rest and sun and moon for reckoning of time. This is the decree of the Exalted, the All-knowing.” (6:96)
“It is He who made sun a lamp, and moon a light and measured stages so you know number of years and count (of time).” (10:5)
“And He subjected the sun and the moon (to His law); each one runs its course for a term appointed.” (13:2), (31:29), (35:13), and (39:5)
It is interesting to note that that the Qur’an refers to many heavens and earths. It is remarkable that one of the more recent discoveries in Astronomy has been that of other worlds such as ours.It was as recently as 1995 that the first planet outside of our solar system was discovered. To date several such planets have been found and extrasolar planets seem to be the rule rather than the exception. How many many aeons ago the Qur’an mentioned this!
“God is the One Who created seven heavens and of the earth a similar number. The command descends upon them so that you know that God has power over all things and comprehends all things in His knowledge.” (65:12)
The Qur’an always refers to the sun and moon differently. The sun is referred to as siraj (light) and zia (signifies that light which exists by itself) while the moon is referred to as nur – which means derived light. This is very accurate since the sun is a celestial body that gives off its own light because of nuclear processes in its interior. However the moon shines only by reflected light.
“And made the moon a light in their midst and made the sun as a (Glorious) lamp.” (71:16)
At the time of revelation of the Qur’an, it was a commonly held belief that the earth stood still and that the sun orbited around us. After all it seemed logical. Man’s ego was bigger than the universe or so he thought. It was easier to believe that he lived in the centre of the universe.
It was not until the16th century that the astronomer Copernicus showed otherwise, that the earth orbited around the sun instead. Just pause and look at the time interval when that piece of information was in the holy Qur’an. Hostility to Science generally and Astronomy particularly was the misfortune of the Catholic Church in the early 16th and 17th century. Let us not imitate them.
“It is He who created the night and the day, and the sun and the moon, all (the celestial bodies) swim along, each in its orbit.” (21:33)
“And the moon, we have measured for her mansions (to traverse) till she returns like the old, (withered, and curved-up like a sickle) date-palm. It is not permitted for sun to catch-up the moon, nor can the night outstrip the day; each swims along in (its own) orbit.” (36:39-40)
The stars adorn our night skies and endow one with a sense of peace with their gentle twinkling. The Qur’an says:
“Consider those (stars) that rise only to set. And move (in their orbits) with steady motion. And float (through space) with floating serene. And yet overtake (one another) with swift overtaking. And thus fulfil the (Creator’s) behest!” (79:1-5)
It is only on the scale of the galaxy that this verse comes to light! A galaxy is composed of millions and millions of stars. A galaxy like ours, the Milky Way is a spiral galaxy and rotates. Yes, the stars do move in an orbit and with steady motion too as they float through space. They do overtake one another because in any spiral structure that is rotating, the outer arms will move at a faster rate than the inner sections and will thereby overtake the stars on the interior in their motion. The spiral nature of our galaxy was only discovered in this century since its spiral nature is not easily evident to us as we reside inside.
There is order, cosmos…not chaos in this tremendous universe. The moon and earth float in orbits and they are predictable in their behaviour. It has been shown that if one planet was removed from our system, our solar system is no longer stable. Comets are predictable and they return as expected bound by the laws of Physics, God’s laws. Man can never truly invent, he can only discover. The Universe is predictable in its behaviour because Allah has subjugated its constituents and they obey him scrupulously, unlike man who has been granted will.
“Then He turned to the sky when it had been gas and said to it and the earth, condense willingly or unwillingly. And they said, “We condensed willingly.” (41:11)
Allah only has to say ‘Be’ and a thing is. It is important to note that present day physics cannot go back to the beginning of time but only very close to the ‘beginning’. The understanding of the physics of the universe begins at t = 10 –43 s, i.e. at 0.0000000000000000000000000000000000000000001 s. We now understand that the early universe was composed of hydrogen and helium gases and some regions were slightly colder or denser than other regions, these regions condensed to become galaxies composed off numerous stars within them. It is as recent as the 1950’s that such ideas have been explored. Yet there it is in the Qur’an as plain as daylight so many many hundreds of years ago. Even the concept of time is worthy of reflecting over. The order of a second may be comfortable to us but we have been able to use atomic clocks for timekeeping which have an accuracy of one part in 1012 .or meaning that if two Caesium clocks are operated they will differ by no more than 1 s after running for 6000 years! In these things are signs of our Lord…. Allah alone is worthy of praise!
“Consider the flight of time!” (103:1)
With respect to the expansion of the universe we find the following verse in the Qur’an:
“And the universe, we constructed with power and skill and verily we are expanding it.” (51:47)
To date all observations show that the Universe is expanding. Galaxies have been observed to be receding away from us at higher and higher speeds, the further away they are. This indicates that we live in an expanding universe. This was discovered in 1926 by Edwin Hubble. The concept of an expanding universe was so alien at the time that it owes to it the famous fudge factor by Albert Einstein. His calculations showed that the Universe should be expanding, but the concept was so bizarre that he included a constant into the equations so as to obtain a static Universe! This he modified later when Hubble observed that the Universe was expanding. It is far easier to be comfortable with the concept of a static universe than one that is expanding. Yet the Qur’an mentions even this, our expanding Universe.
“He Who created the seven heavens, one above another: No want of proportion will you see in the creation of Most Gracious, so turn your face again; Do you see any flaw ... .... And We have adorned the lowest heaven with lamps ....” (67:3-5)
The Role Of Astronomy In Islam - Part 2
Dr. Shirin Haque-Copilah
Physics Dept, Univ. of the West Indies
Contribution of Muslim scholars to the development of Astronomy
The first verse that was ever revealed to Prophet Muhammad (UWBP) implores man towards the acquisition of knowledge:
“Read in the name of thy Sustainer, who has created – created man out of a germ cell! Read – for thy Sustainer is the Most Bountiful One. Who has taught (man) the use of the pen – Taught man what he did not know!” (96: 1-5)
A quick browsing through the holy Qur’an shows many Surahs beginning with astronomical references: “Consider those (stars) that rise only to set” (79:1)
“Consider the heavens and that which comes in the night” (86:1)
“Consider the sun and its radiant brightness and the moon as it reflects the sun!” (91:1)” …… “Consider the sky and its wondrous make” (91:5)
“Consider the night as it veils (the earth) in darkness” (92:1)
It is our moral obligation to study Astronomy! Given the exposition in the previous section, it would seem natural that Astronomy should get its impetus first and foremost from Muslim Scholars. And so it was in the early years of Islam. Sadly, this trend has suffered a serious decline in the last few centuries. It is really interesting to note that Muslims were in fact the first to differentiate and separate the science of Astronomy from the pseudo science of astrology. The development of Astronomy suffered a great decline and the last of the great Muslim astronomers was Fakhr al-Din al-Razi (d. 1228 CE). Let us venture back in time and see the richness of the pursuit of knowledge particularly in Astronomy in the early days of Islam. Contributions to Astronomy by Muslim scholars will naturally include contributions to Mathematics and Physics that are indispensable tools for the study of Astronomy. If the tradition of seeking knowledge as Islam emphasizes had continued, Astronomy would have continued to flourish among Muslim scholars and no doubt have been centuries ahead of our time as we have seen from the expositions in the previous sections as highlighted in the holy Qur’an.
Greek works were translated by Muslim scholars in Arabic and they also added encyclopaedias of their own. When Europe later re-awoke, they translated the Arabic works and the Arabic translations of the Greek works. Star names were not translated but transliterated so that to date many many stars names are Arabic in origin. A look through any catalogue of stars, and one is immediately struck by the numerous names that appear to be Arabic in origin such as Aldabaran and Deneb. In an astronomical catalogue of almost 250 stars, over 140 of them had names that were Arabic in origin. Many new stars were discovered by Muslims. The book on stars of 'Abd al-Rahman al-Sufi was in fact translated into Spanish by Alfonso X el Sabio. The Muslims carried out many observations that were contained in astronomical tables called Zij. One of the most keen observers was al-Battani. The zij of al-Ma'mun observed in Baghdad, the Hakimite zij of Cairo, the Toledan Tables of al-Zarqali and his associates, the el-Khanid zij of Nasir al-Din al-Tusi observed in Maraghah, and the zij of Ulugh-Beg from Samarqand are among the most famous Islamic astronomical tables. These tables had significant influence upon Western Astronomy up to the time of Astronomer Tycho Brahe.
In Astronomy the Muslims integrated the astronomical traditions of the Indians, Persians, the ancient Near East and especially the Greeks from the 8th century onward. The Almagest of Ptolemy, the name of which is Arabic in origin, was thoroughly studied and its planetary theory criticized by several astronomers of both the eastern and western lands of Islam. A major critique of the theory was developed by Nasir al-Din al-Tusi and his students especially Qutb al-Din al-Shirazi, in the 13th century.
The first astronomical observatory as a scientific institution was the observatory of Maraghah in Persia established by al-Tusi. Later European observatories indirectly followed this model. The most famous astronomical instrument, the astrolabe was developed by Muslims to carry out observation. There existed even mechanical astrolabes perfected by Ibn Samh that can be considered as the predecessor of the mechanical clock.
The Muslims also applied their astronomical knowledge to questions of time-keeping and the calendar in making almanacs, this word too being Arabic in origin. The most exact solar calendar existing to this day is the Jalali calendar which was developed under the direction of 'Umar Khayyam in the 12th century. This is still in use in Persia and Afghanistan.
In the field of Mathematics, Muslims began by integrating Greek and Indian mathematics. The first great Muslim mathematician, al-Khwarazmi, who lived in the 9th century, wrote a treatise on arithmetic that brought the Arabic numerals to the West. He is also the author of the first book on algebra. The term algebra itself comes from the first part of the name of the book of al-Khwarazmi, entitled Kirah al-jabr wa'l-muqabalah. Abu Kamil al-Shuja' discussed algebraic equations with five unknowns. The science was further developed by such figures as al-Karaji until it reached its peak with Khayyam who classified by kind and class algebraic equations up to the third degree. The brothers Banu Musa who lived in the 9th century may be said to be the first outstanding Muslims in the field of geometry while their contemporary Thabit ibn Qurrah helped lay foundations of integral calculus. Muslims scholars also developed trigonometry that was established as a distinct branch of mathematics by al-Biruni. Calculus, trigonometry and geometry are the cornerstones of solving problems in Astronomy.
Other Muslim mathematicians such as Khayyam and al-Tusi examined Euclidean geometry that is the geometry of flat surfaces. The Muslim mathematicians, especially al-Battani, Abu'l-Wafa', Ibn Yunus and Ibn al-Haytham, also developed spherical Astronomy. Euclidean and spherical geometry are particularly useful in studying the overall geometry of the Universe in the study of cosmology.
The works of Ibn Sina, Abu'l-Barakat al-Baghdadi, Ibn Bajjah and others led to the development of the idea of impetus and momentum, principles in Physics that are applied to motion of bodies in Astronomy. Another area that is important in Astronomy is optics. It is very relevant in the development of tools for observation like telescopes that employ lenses or mirrors. Ibn al-Haytham (the Latin Alhazen) who lived in the 11th century was one of the greatest student of optics between Ptolemy and Witelo. Ibn al-Haytham's main work on optics, the Kitab al-manazir, was also well known in the West as Thesaurus opticus. Ibn al-Haytham studied the property of lenses, discovered the camera obscura, explained correctly the process of vision, studied the structure of the eye, and explained for the first time why the sun and the moon appear larger on the horizon (very simply put, it is because the thicker layer of atmosphere at the horizon acts as magnifying lens compared to overhead). His interest in optics was carried out two centuries later by Qutb al-Din al-Shirazi and Kamal al-Din al-Farisi. It was Qutb al-Din who gave the first correct explanation of the formation of the rainbow.
Muhammad ibn Jabir al-Battani , one of the top twenty astronomers in the history of civilization comments
“ [Astronomy] has a well earned place among disciplines for its tremendous share in helping man calculate years and months, provide accurate time, mark seasons, observe increase and decrease in duration of days and nights, watch locations and eclipses of the sun and the moon, witness the movements of planets in their faring in alternating places and signs. Much more may be added by it through study and scrutiny that invariably leads to further proof and knowledge of the greatness, wisdom, and power of the Creator (SWT)”
The holy Qur’an is full of gems of expositions in Astronomy - a sprinkling of which have been highlighted in this article. That in itself should be an inspiration to Muslim scholars to continue in the present day the pursuit of knowledge in the Sciences. Like in the days of yore, we should strive to develop a culture that is scientifically rich in the understanding of natural phenomena by “men of understanding”.
In the past few years, there has been a concerted effort by many well-informed Muslims of the need to use Astronomy for the establishment of the beginning of the months. In this connection it is useful to note the following verse from the holy Qur’an:
“The sun and moon (are subjected) to calculations.” (55:05)
The informed Muslim community are now taking these matters very seriously and
there is an international effort via CFCO (Committee For Crescent Observation), an active society since 1978, and the more recent ICOP (Islamic Crescent Observation Project), both of which include members from all over the world whose job it is to observe the crescent young moon not only for the months indicating the beginning Ramadan or its end, but all year long. This issue has been a bone of contention time and time again among Muslims. In this connection, it would be useful to highlight the words of noted fiqh scholar Dr. Taha Jabir al-Alwani from his book Ijtihad1 with respect to the sighting of the moon for the start and end of the holy month of Ramadan. Dr. al-Alwani in pointing out the necessity and significance of Ijtihad in relation to Time-Space factor uses the sighting of the moon as an example, and I quote him:
Ijtihad (1993) Published by International Institute of Islamic Thought,USA. p. 27
”…It could never have been the prophet’s intention to make life so difficult when he established that rule. He was, at that time, addressing illiterate people, and the best they could do to establish the beginning of the month was to see the moon with the naked eye. They had no other means and Allah (SWT) did not wish to make matters difficult or impossible for them. But when there exists more accurate instruments to determine the same fact, it would be totally unacceptable, and indeed backward looking, if insistence is on using out-dated and inadequate methods. The message of Islam is intended for all people in all ages; it was never restricted to the first hijri century Arabs of Makkah. Therefore, to stick to the literal meaning irrespective of the time factor is a benighted approach which is conducive neither to enlightment nor to progress.”
One can be guided by astronomical calculations to help one to know when and where to search for the crescent moon. This has brought to light that many countries have hitherto been in error in establishing the beginning of the new month, Saudi Arabia included. Some have accepted they have been in error and are now revising their position on that count. It is important that we do not follow blindly but we seek to understand and convince ourselves of the correctness of methods employed. The modern era of internet access and electronic communication seeks to educate and unite us as Muslims like we never could before.
There are now several different softwares available for calculating the dates and times of new moons, prayer times and qibla direction. The study of Astronomy is not something to be afraid of - it enlightens us and guides to a deeper understanding and appreciation of our religion and recognition of the omnipotence of our Creator. There is nothing wrong if in searching for the crescent moon we know when and where to look for it. Over and over the Qur’an emphasizes the aspect “for men of understanding”. We need to listen to that, surely there is great importance and relevance for it to be repeated so many times
The Prophet Muhammad (PBUH) has said “ Seek knowledge from the cradle to the grave”. Islam is about a lifetime of learning. A lifetime of learning means we can never know or understand everything. It is a dynamic process and we must continue to strive at all times.
“Verily, in the creation of the heavens and the earth, and in the succession of night and day, there are indeed messages for all who are endowed with insight, (3:190)
(and) who remember God when they stand, and when they sit, and when they lie down to sleep, and (thus) reflect on the creation of the heavens and the earth: “ O our Sustainer! Thou hast not created (aught of) this without meaning and purpose. Limitless art Thou in Thy glory! Keep us safe, then from suffering through fire!” (3:191)
“Praise the name of your Lord, the Most High, Who creates and proportions well, Who determines and guides” (87:1-3)
Physics Dept, Univ. of the West Indies
Contribution of Muslim scholars to the development of Astronomy
The first verse that was ever revealed to Prophet Muhammad (UWBP) implores man towards the acquisition of knowledge:
“Read in the name of thy Sustainer, who has created – created man out of a germ cell! Read – for thy Sustainer is the Most Bountiful One. Who has taught (man) the use of the pen – Taught man what he did not know!” (96: 1-5)
A quick browsing through the holy Qur’an shows many Surahs beginning with astronomical references: “Consider those (stars) that rise only to set” (79:1)
“Consider the heavens and that which comes in the night” (86:1)
“Consider the sun and its radiant brightness and the moon as it reflects the sun!” (91:1)” …… “Consider the sky and its wondrous make” (91:5)
“Consider the night as it veils (the earth) in darkness” (92:1)
It is our moral obligation to study Astronomy! Given the exposition in the previous section, it would seem natural that Astronomy should get its impetus first and foremost from Muslim Scholars. And so it was in the early years of Islam. Sadly, this trend has suffered a serious decline in the last few centuries. It is really interesting to note that Muslims were in fact the first to differentiate and separate the science of Astronomy from the pseudo science of astrology. The development of Astronomy suffered a great decline and the last of the great Muslim astronomers was Fakhr al-Din al-Razi (d. 1228 CE). Let us venture back in time and see the richness of the pursuit of knowledge particularly in Astronomy in the early days of Islam. Contributions to Astronomy by Muslim scholars will naturally include contributions to Mathematics and Physics that are indispensable tools for the study of Astronomy. If the tradition of seeking knowledge as Islam emphasizes had continued, Astronomy would have continued to flourish among Muslim scholars and no doubt have been centuries ahead of our time as we have seen from the expositions in the previous sections as highlighted in the holy Qur’an.
Greek works were translated by Muslim scholars in Arabic and they also added encyclopaedias of their own. When Europe later re-awoke, they translated the Arabic works and the Arabic translations of the Greek works. Star names were not translated but transliterated so that to date many many stars names are Arabic in origin. A look through any catalogue of stars, and one is immediately struck by the numerous names that appear to be Arabic in origin such as Aldabaran and Deneb. In an astronomical catalogue of almost 250 stars, over 140 of them had names that were Arabic in origin. Many new stars were discovered by Muslims. The book on stars of 'Abd al-Rahman al-Sufi was in fact translated into Spanish by Alfonso X el Sabio. The Muslims carried out many observations that were contained in astronomical tables called Zij. One of the most keen observers was al-Battani. The zij of al-Ma'mun observed in Baghdad, the Hakimite zij of Cairo, the Toledan Tables of al-Zarqali and his associates, the el-Khanid zij of Nasir al-Din al-Tusi observed in Maraghah, and the zij of Ulugh-Beg from Samarqand are among the most famous Islamic astronomical tables. These tables had significant influence upon Western Astronomy up to the time of Astronomer Tycho Brahe.
In Astronomy the Muslims integrated the astronomical traditions of the Indians, Persians, the ancient Near East and especially the Greeks from the 8th century onward. The Almagest of Ptolemy, the name of which is Arabic in origin, was thoroughly studied and its planetary theory criticized by several astronomers of both the eastern and western lands of Islam. A major critique of the theory was developed by Nasir al-Din al-Tusi and his students especially Qutb al-Din al-Shirazi, in the 13th century.
The first astronomical observatory as a scientific institution was the observatory of Maraghah in Persia established by al-Tusi. Later European observatories indirectly followed this model. The most famous astronomical instrument, the astrolabe was developed by Muslims to carry out observation. There existed even mechanical astrolabes perfected by Ibn Samh that can be considered as the predecessor of the mechanical clock.
The Muslims also applied their astronomical knowledge to questions of time-keeping and the calendar in making almanacs, this word too being Arabic in origin. The most exact solar calendar existing to this day is the Jalali calendar which was developed under the direction of 'Umar Khayyam in the 12th century. This is still in use in Persia and Afghanistan.
In the field of Mathematics, Muslims began by integrating Greek and Indian mathematics. The first great Muslim mathematician, al-Khwarazmi, who lived in the 9th century, wrote a treatise on arithmetic that brought the Arabic numerals to the West. He is also the author of the first book on algebra. The term algebra itself comes from the first part of the name of the book of al-Khwarazmi, entitled Kirah al-jabr wa'l-muqabalah. Abu Kamil al-Shuja' discussed algebraic equations with five unknowns. The science was further developed by such figures as al-Karaji until it reached its peak with Khayyam who classified by kind and class algebraic equations up to the third degree. The brothers Banu Musa who lived in the 9th century may be said to be the first outstanding Muslims in the field of geometry while their contemporary Thabit ibn Qurrah helped lay foundations of integral calculus. Muslims scholars also developed trigonometry that was established as a distinct branch of mathematics by al-Biruni. Calculus, trigonometry and geometry are the cornerstones of solving problems in Astronomy.
Other Muslim mathematicians such as Khayyam and al-Tusi examined Euclidean geometry that is the geometry of flat surfaces. The Muslim mathematicians, especially al-Battani, Abu'l-Wafa', Ibn Yunus and Ibn al-Haytham, also developed spherical Astronomy. Euclidean and spherical geometry are particularly useful in studying the overall geometry of the Universe in the study of cosmology.
The works of Ibn Sina, Abu'l-Barakat al-Baghdadi, Ibn Bajjah and others led to the development of the idea of impetus and momentum, principles in Physics that are applied to motion of bodies in Astronomy. Another area that is important in Astronomy is optics. It is very relevant in the development of tools for observation like telescopes that employ lenses or mirrors. Ibn al-Haytham (the Latin Alhazen) who lived in the 11th century was one of the greatest student of optics between Ptolemy and Witelo. Ibn al-Haytham's main work on optics, the Kitab al-manazir, was also well known in the West as Thesaurus opticus. Ibn al-Haytham studied the property of lenses, discovered the camera obscura, explained correctly the process of vision, studied the structure of the eye, and explained for the first time why the sun and the moon appear larger on the horizon (very simply put, it is because the thicker layer of atmosphere at the horizon acts as magnifying lens compared to overhead). His interest in optics was carried out two centuries later by Qutb al-Din al-Shirazi and Kamal al-Din al-Farisi. It was Qutb al-Din who gave the first correct explanation of the formation of the rainbow.
Muhammad ibn Jabir al-Battani , one of the top twenty astronomers in the history of civilization comments
“ [Astronomy] has a well earned place among disciplines for its tremendous share in helping man calculate years and months, provide accurate time, mark seasons, observe increase and decrease in duration of days and nights, watch locations and eclipses of the sun and the moon, witness the movements of planets in their faring in alternating places and signs. Much more may be added by it through study and scrutiny that invariably leads to further proof and knowledge of the greatness, wisdom, and power of the Creator (SWT)”
The holy Qur’an is full of gems of expositions in Astronomy - a sprinkling of which have been highlighted in this article. That in itself should be an inspiration to Muslim scholars to continue in the present day the pursuit of knowledge in the Sciences. Like in the days of yore, we should strive to develop a culture that is scientifically rich in the understanding of natural phenomena by “men of understanding”.
In the past few years, there has been a concerted effort by many well-informed Muslims of the need to use Astronomy for the establishment of the beginning of the months. In this connection it is useful to note the following verse from the holy Qur’an:
“The sun and moon (are subjected) to calculations.” (55:05)
The informed Muslim community are now taking these matters very seriously and
there is an international effort via CFCO (Committee For Crescent Observation), an active society since 1978, and the more recent ICOP (Islamic Crescent Observation Project), both of which include members from all over the world whose job it is to observe the crescent young moon not only for the months indicating the beginning Ramadan or its end, but all year long. This issue has been a bone of contention time and time again among Muslims. In this connection, it would be useful to highlight the words of noted fiqh scholar Dr. Taha Jabir al-Alwani from his book Ijtihad1 with respect to the sighting of the moon for the start and end of the holy month of Ramadan. Dr. al-Alwani in pointing out the necessity and significance of Ijtihad in relation to Time-Space factor uses the sighting of the moon as an example, and I quote him:
Ijtihad (1993) Published by International Institute of Islamic Thought,USA. p. 27
”…It could never have been the prophet’s intention to make life so difficult when he established that rule. He was, at that time, addressing illiterate people, and the best they could do to establish the beginning of the month was to see the moon with the naked eye. They had no other means and Allah (SWT) did not wish to make matters difficult or impossible for them. But when there exists more accurate instruments to determine the same fact, it would be totally unacceptable, and indeed backward looking, if insistence is on using out-dated and inadequate methods. The message of Islam is intended for all people in all ages; it was never restricted to the first hijri century Arabs of Makkah. Therefore, to stick to the literal meaning irrespective of the time factor is a benighted approach which is conducive neither to enlightment nor to progress.”
One can be guided by astronomical calculations to help one to know when and where to search for the crescent moon. This has brought to light that many countries have hitherto been in error in establishing the beginning of the new month, Saudi Arabia included. Some have accepted they have been in error and are now revising their position on that count. It is important that we do not follow blindly but we seek to understand and convince ourselves of the correctness of methods employed. The modern era of internet access and electronic communication seeks to educate and unite us as Muslims like we never could before.
There are now several different softwares available for calculating the dates and times of new moons, prayer times and qibla direction. The study of Astronomy is not something to be afraid of - it enlightens us and guides to a deeper understanding and appreciation of our religion and recognition of the omnipotence of our Creator. There is nothing wrong if in searching for the crescent moon we know when and where to look for it. Over and over the Qur’an emphasizes the aspect “for men of understanding”. We need to listen to that, surely there is great importance and relevance for it to be repeated so many times
The Prophet Muhammad (PBUH) has said “ Seek knowledge from the cradle to the grave”. Islam is about a lifetime of learning. A lifetime of learning means we can never know or understand everything. It is a dynamic process and we must continue to strive at all times.
“Verily, in the creation of the heavens and the earth, and in the succession of night and day, there are indeed messages for all who are endowed with insight, (3:190)
(and) who remember God when they stand, and when they sit, and when they lie down to sleep, and (thus) reflect on the creation of the heavens and the earth: “ O our Sustainer! Thou hast not created (aught of) this without meaning and purpose. Limitless art Thou in Thy glory! Keep us safe, then from suffering through fire!” (3:191)
“Praise the name of your Lord, the Most High, Who creates and proportions well, Who determines and guides” (87:1-3)
Monday, June 15, 2009
Teaching Islamic Economics - Part 1
The first leading university in the area of teaching Islamic economics as an academic subject is Al-Azhar University. This teaching is administered in two faculties : The Faculty of Commerce (Within the curriculum of the fourth level of the Bachelor’s program), and the faculty of Sharia (within the curriculum of the Legal Politics degree in the graduate program).
This subject matter has been introduced only recently by virtue of law no.102 issued in 1961 on the restructuring of Al Azhar and its constituent institutions. This development occurred quite late, in spite of the long-established existence of Islamic economics which is as old as Islam itself and whose emergence took place fourteen centuries ago. It also occurred quite late in spite of the opinion expressed by Moslem and non-Moslem theologians, and pertaining to the fact that Islamic economics, on the one hand, is unique and enjoys a separate identity and on the other hand, that the foundations and principles that underlie it meet the needs of modern times and guarantee man’s happiness on earth and in the Hereafter. Furthermore, the introduction of Islamic economics into school curricula was started quite late in spite of the enthusiasm shown by the Moslem peoples and their leaders towards the application of the precepts that contain the principles of Islamic economics.
It seems that the issue involves a missing link. We shall try to clarify this in the following three sections :
1. The novelty of Islamic economics as a subject matter.
2. Neglecting the teaching of Islamic economics as a school subject.
3. Neglecting the application of Islamic economics.
3.1. The Novelty of Islamic Economics
3.1.1.Islamic Economics is as Old as Islam Itself
As it has been indicated earlier, Islam is not simply a religious faith; it is also a political, social and economic system for the Islamic society. That is what is intended by the phrases that describe Islam as “a religion and a code of life”, and as ‘a faith and Sharia”.
Islam was not revealed to man for spiritual guidance, as was Christianity which advocates the principle of "Give to Caesar what belongs to Caesar and to God what belongs to God”. Instead, Islam came in order to organize man’s life in all its aspects, whether they are political, social or economic. The Messenger Mohammad, may Allah’s prayer and peace be upon Him, was not only a Prophet but also an executive judge.
Thus, Islamic economics is as old as Islam itself.
3.1.2.The Novelty of Islamic Economics as a Subject Matter
Although Islamic economics dates back to, the emergence of Islam fourteen centuries ago, its introduction into teaching curricula as a separate subject is a flew development. Besides, the research and the areas of study pertaining to this subject are still limited.
Our objective is not to explore the reasons for this failure or that contradiction. Suffice it to point out that Islam has brought new principles and unique foundations in the area of economics. The study of Islamic economics knew its heyday in the early Islamic era, to the extent that several old books are full of original ideas that compare favorably with the modern concepts and theories of economics. More than that, the first world scientifically-oriented books of economics did not appear until the Seventh century (Gregorian), in the light of Islam and through the creativity of Arab writers (See Salah, 1932, Nachaat, 1944 and Mourad, 1952). Subsequently, the study of Islamic economics declined following the cessation of the Ijtihad in the fourth century (Islamic calendar). Since that time, there has been almost no research on Islamic law and, consequently, the studies on Islamic economics have ceased to face the changing needs of society.
This state of affairs has caused the study of Islamic economics to lag behind to such an extent that the content of this subject matter has. been forgotten even by the Moslems themselves and faded out of the minds of their own theologists. Several intellectuals still do not imagine the existence of an Islamic economic system which can meet the needs of modern society and compare favorably with the two dominant economic systems of capitalism and socialism.
3.1.3.Type of Effort Required in the Subject Matter of Islamic Economics
There may now be strong calls for going back to Islam, with the view of applying its economic principles and involving it in the solution of the world problems. However, before doing so, we need to clearly show these economic foundations and the manner in which they can be applied for the benefit of each society and in accordance with the conditions of time and space.
The true enthusiasm and the sincere calls in favor of Islamic economics will be wasted if no efforts are made to highlight the political social and economic precepts of Islam in the Language of modern times, and if no explanations are given as to how these precepts can be applied in such a way as to further the changing interests of society. If such conditions are met, instead of seeking the adoption of the Islamic precepts through mere talk and dogmatism, these godly precepts will impose themselves not only to the Islamic countries but to the whole world, for it is in all times and places the road to salvation. peace and happiness for all humanity.
From the above we can realize the necessity of economics as a scientific and separate subject which lends itself to wide ranging research studies on the economic problems of our times and which finds the Islamic solutions for them.
3.2.Neglecting the Teaching of Islamic Economics
3.2.1.World’s Aspiration Towards Islamic Economics
As it has been indicated earlier, Islamic economics is an independent system which enjoys a separate identity. It is a self-contained system with its own economic policy which encompasses all the different interests - (whether private or public material or spiritual)-, takes into consideration the variations in time and space and, in the final analysis, achieves all the advantageous results and avoids all the inconveniences.
Several foreign and international voices cry out in order to stress the fact that Islamic economics is the hope for the salvation of humanity from the extremist positions adopted by each of the two dominant economic systems capitalism and socialism.
3.2.2.Islamic Universities’ Neglect of Teaching Islamic Economics
In spite of all that, the majority of the universities in the Islamic world itself provide courses on the capitalist and socialist economic systems but not on the Islamic one.
In Egypt, we have created specialized faculties of economics, such as the Faculty of Economics and Political Science, without any mention of the study of Islamic economics. Worse than that, we have set up specialized institutes for Arabic and Islamic studies such as the Institute for Advanced Arab Studies. in which we do not provide any teaching on Islamic economics as a separate subject and yet it is the area of Arabic and Islamic studies that is most worthy of our attention and care.
As was indicated earlier, Al-Azhar University, especially its Commerce and Sharia faculties, is the first leading university in the teaching of Islamic economics as an independent and scientific subject following a law related to the restructuring of Al-Azhar and issued under number 102 in the year 1961. Then there was King Abdulaziz University (Faculty of Economics) in Jeddah Which became the second leading university in the teaching of Islamic economics by virtue of its statutes issued in 1374H/1964 Later. the Seventh Conference of Moslem Ulema held in Cairo in September 1972. issued a resolution on the necessity to teach Islamic economics in the different institutes and universities of the Islamic world. Unfortunately this resolution has not found its way to application until after the First World Conference on Islamic economics which was held in Holy Mecca in February 1976.
Today, Islamic economics has almost become one of the prescribed subjects in several institutes and universities of the Islamic World. especially in the Kingdom of Saudi Arabia, although it has been harmed by some faculties by including it within the subject of Islamic culture.
Some Islamic universities and their specialized institutions may excuse themselves for not teaching Islamic economics as an independent subject by arguing that it is a new study area whose components have not been clearly delineated and about which there are limited basic references. However, is this not one more reason why Islamic universities and institutions should have set up departments and professorship chairs that are specialized in this subject matter ? Such an action will attract interested students and will consequently generate the relevant research, activate the study of the subject and foster its existence, thus imposing it on human thought. It will also play an effective role in the service of Islam and in the guidance of Moslems’ life.
http://www.ymsite.com
This subject matter has been introduced only recently by virtue of law no.102 issued in 1961 on the restructuring of Al Azhar and its constituent institutions. This development occurred quite late, in spite of the long-established existence of Islamic economics which is as old as Islam itself and whose emergence took place fourteen centuries ago. It also occurred quite late in spite of the opinion expressed by Moslem and non-Moslem theologians, and pertaining to the fact that Islamic economics, on the one hand, is unique and enjoys a separate identity and on the other hand, that the foundations and principles that underlie it meet the needs of modern times and guarantee man’s happiness on earth and in the Hereafter. Furthermore, the introduction of Islamic economics into school curricula was started quite late in spite of the enthusiasm shown by the Moslem peoples and their leaders towards the application of the precepts that contain the principles of Islamic economics.
It seems that the issue involves a missing link. We shall try to clarify this in the following three sections :
1. The novelty of Islamic economics as a subject matter.
2. Neglecting the teaching of Islamic economics as a school subject.
3. Neglecting the application of Islamic economics.
3.1. The Novelty of Islamic Economics
3.1.1.Islamic Economics is as Old as Islam Itself
As it has been indicated earlier, Islam is not simply a religious faith; it is also a political, social and economic system for the Islamic society. That is what is intended by the phrases that describe Islam as “a religion and a code of life”, and as ‘a faith and Sharia”.
Islam was not revealed to man for spiritual guidance, as was Christianity which advocates the principle of "Give to Caesar what belongs to Caesar and to God what belongs to God”. Instead, Islam came in order to organize man’s life in all its aspects, whether they are political, social or economic. The Messenger Mohammad, may Allah’s prayer and peace be upon Him, was not only a Prophet but also an executive judge.
Thus, Islamic economics is as old as Islam itself.
3.1.2.The Novelty of Islamic Economics as a Subject Matter
Although Islamic economics dates back to, the emergence of Islam fourteen centuries ago, its introduction into teaching curricula as a separate subject is a flew development. Besides, the research and the areas of study pertaining to this subject are still limited.
Our objective is not to explore the reasons for this failure or that contradiction. Suffice it to point out that Islam has brought new principles and unique foundations in the area of economics. The study of Islamic economics knew its heyday in the early Islamic era, to the extent that several old books are full of original ideas that compare favorably with the modern concepts and theories of economics. More than that, the first world scientifically-oriented books of economics did not appear until the Seventh century (Gregorian), in the light of Islam and through the creativity of Arab writers (See Salah, 1932, Nachaat, 1944 and Mourad, 1952). Subsequently, the study of Islamic economics declined following the cessation of the Ijtihad in the fourth century (Islamic calendar). Since that time, there has been almost no research on Islamic law and, consequently, the studies on Islamic economics have ceased to face the changing needs of society.
This state of affairs has caused the study of Islamic economics to lag behind to such an extent that the content of this subject matter has. been forgotten even by the Moslems themselves and faded out of the minds of their own theologists. Several intellectuals still do not imagine the existence of an Islamic economic system which can meet the needs of modern society and compare favorably with the two dominant economic systems of capitalism and socialism.
3.1.3.Type of Effort Required in the Subject Matter of Islamic Economics
There may now be strong calls for going back to Islam, with the view of applying its economic principles and involving it in the solution of the world problems. However, before doing so, we need to clearly show these economic foundations and the manner in which they can be applied for the benefit of each society and in accordance with the conditions of time and space.
The true enthusiasm and the sincere calls in favor of Islamic economics will be wasted if no efforts are made to highlight the political social and economic precepts of Islam in the Language of modern times, and if no explanations are given as to how these precepts can be applied in such a way as to further the changing interests of society. If such conditions are met, instead of seeking the adoption of the Islamic precepts through mere talk and dogmatism, these godly precepts will impose themselves not only to the Islamic countries but to the whole world, for it is in all times and places the road to salvation. peace and happiness for all humanity.
From the above we can realize the necessity of economics as a scientific and separate subject which lends itself to wide ranging research studies on the economic problems of our times and which finds the Islamic solutions for them.
3.2.Neglecting the Teaching of Islamic Economics
3.2.1.World’s Aspiration Towards Islamic Economics
As it has been indicated earlier, Islamic economics is an independent system which enjoys a separate identity. It is a self-contained system with its own economic policy which encompasses all the different interests - (whether private or public material or spiritual)-, takes into consideration the variations in time and space and, in the final analysis, achieves all the advantageous results and avoids all the inconveniences.
Several foreign and international voices cry out in order to stress the fact that Islamic economics is the hope for the salvation of humanity from the extremist positions adopted by each of the two dominant economic systems capitalism and socialism.
3.2.2.Islamic Universities’ Neglect of Teaching Islamic Economics
In spite of all that, the majority of the universities in the Islamic world itself provide courses on the capitalist and socialist economic systems but not on the Islamic one.
In Egypt, we have created specialized faculties of economics, such as the Faculty of Economics and Political Science, without any mention of the study of Islamic economics. Worse than that, we have set up specialized institutes for Arabic and Islamic studies such as the Institute for Advanced Arab Studies. in which we do not provide any teaching on Islamic economics as a separate subject and yet it is the area of Arabic and Islamic studies that is most worthy of our attention and care.
As was indicated earlier, Al-Azhar University, especially its Commerce and Sharia faculties, is the first leading university in the teaching of Islamic economics as an independent and scientific subject following a law related to the restructuring of Al-Azhar and issued under number 102 in the year 1961. Then there was King Abdulaziz University (Faculty of Economics) in Jeddah Which became the second leading university in the teaching of Islamic economics by virtue of its statutes issued in 1374H/1964 Later. the Seventh Conference of Moslem Ulema held in Cairo in September 1972. issued a resolution on the necessity to teach Islamic economics in the different institutes and universities of the Islamic world. Unfortunately this resolution has not found its way to application until after the First World Conference on Islamic economics which was held in Holy Mecca in February 1976.
Today, Islamic economics has almost become one of the prescribed subjects in several institutes and universities of the Islamic World. especially in the Kingdom of Saudi Arabia, although it has been harmed by some faculties by including it within the subject of Islamic culture.
Some Islamic universities and their specialized institutions may excuse themselves for not teaching Islamic economics as an independent subject by arguing that it is a new study area whose components have not been clearly delineated and about which there are limited basic references. However, is this not one more reason why Islamic universities and institutions should have set up departments and professorship chairs that are specialized in this subject matter ? Such an action will attract interested students and will consequently generate the relevant research, activate the study of the subject and foster its existence, thus imposing it on human thought. It will also play an effective role in the service of Islam and in the guidance of Moslems’ life.
http://www.ymsite.com
Teaching Islamic Economics - Part 2
3.2.3.The Mission to be Accomplished by the Leaders of Islamic Economics
When departments and chairs are created for Islamic economics, occupants will have numerous difficult responsibilities, especially the following :
1. Preparing studies on Koran and Sunna texts that relate to Islamic economics, showing how these texts can be implemented in ways that are consistent with the conditions of time and space, and suggesting Islamic solutions for the different economic problems of the time.
2. Conducting comparative studies between the Islamic and other economic systems showing the extent to which the differences in their respective applications are a result of differences in the systems themselves, and providing an evaluation of each system.
3. Consulting the volumes written by the experts on Islamic Sharia, extracting their detailed opinions on questions of economics and expressing them in terms used in the current economic literature along with the presentation of relevant commentaries.
4. Keeping abreast of the developments in the economic thought among the Islamic thinkers through out the different Islamic eras and countries, identifying the differences among them, and determining the bases of each opinion and presenting an evaluation of it.
5. Supervising the setting up of a scientific library which contains the volumes research studies, dissertations and specialized journals that deal with economics in Islam.
6. Encouraging the writing of master’s and doctoral dissertations in Islamic economics and providing for the training of young researchers who combine the two cultures the first being one of Islam and Fiqh (Islamic jurisprudence) and the second being one of technical economics.
7. Studying the economic situations in the Islamic world investigating the underdevelopment that it suffers from, and drawing plans for the setting up of Islamic economic structures which will ensure cooperation among Islamic countries and their complementarily, and will benefit humanity.
We are not being unrealistic in our recommendations. We look forward to the setting up within the Islamic world of centers or institutes that are specialized in Islamic economics.
[Note: The First World Conference on Islamic Economics which was convened by the Kingdom of Saudi Arabia and organized by Kint Abdelaziz University in Holy Mecca in Safar 139 February 1976 led to he creation of the World Center for Research on Islamic Economics (as a part of King Abdelaziz University). Similarly. the First World Conference on Fiqh which was convened by the Kingdom of Saudi Arabia and organized by Imam Mohamed Ibn Saoud University in Ryad in Do Lqiada. 1396/November 1976 led to the creation of a department of Islamic Economics in the Sharia faculties. The department is intended for the study of Islamic economics in four complete years and started operating in the academic year 1399-1400 AH. Later this department became a separate Faculty of Islamic Economics. In addition to the above. the Commerce Faculty of the AI-Azhar University took the initiative of setting up the "Sheikh Abdellah Kamil Center for Research and Studies on Islamic Commerce” which delivers, in the name of AI-Azhar University master’s and doctoral degrees in Islamic economics.]
Economy is the vital context which reveals the material and spiritual strength of Islam and through which the Islamic Ummah can achieve its cohesion, strength and universal mission.
3.3. Neglecting the Application of Islamic Economics
3.3.1.Gap between Belief and Reality
Nobody doubts the Moslems’ faith in Islam and nobody questions their belief in the soundness of the principles that constitute the basis of this religion, especially in the context of the organization of society in its political. social and economic activities.
Several voices cry out at different official and non-official levels some die out in insistence while others burst out in anger calling for the application of the foundations and the principles of Islamic economics. Sometimes, these voices find attentive ears and a strong echo among the people in charge as well as a sincere response and a confirmed interest on the part of the peoples and their leaders. However, the response stops there.
3.3.2. The Reasons for not Applying the Principles of Islamic Economics
Although the Moslem peoples and their leaders adhere to Islam and experience the application of the Sharia, they, nonetheless, seek the solutions to their different economic problems outside Islam and thus, we see their societies swinging awkwardly between the capitalist and socialist systems, neglecting their Islamic economic system.
This state of affairs does not mean the forsaking of Islam or doubt about its economic principles. Neither does it mean negligence on the part of Moslems or atavism (reversion) on the part of the leaders. The reason for not applying the principles of Islamic economics is that the solutions which are presented in the name of Islam for the problems of our modern times (and they are complex economic problems) are simplistic and unpractical. In fact these solutions are suggested by some men of religion who are not specialized in economic matters, relying in doing so on some old time religious leaders or theologists. In doing so, they ignore some important matters which are as follows :
1. Islam does not have a place for men of religion as such for all Moslems are men of religion. However, it does have a status for men of knowledge. Nowadays, it is not enough for a person to be educated in the large domain of Fiqh in order to be able to formulate legal opinions about modern complex economic matters. Rather. it is necessary for him, in addition to that, to have a specialized knowledge that comprises the foundations and the details of the economics science.
2. The judgments by Ijtihad made by the old time Islamic leaders and theologists, in spite of their great importance, cannot be taken in their absolute meanings. since they are essentially opinions. Added to this is the fact that most of these judgments were formulated in a period and in conditions which are not ours and on problems which are not ours. Today. We are called upon to make serious attempts as the old time theologists did in order to reveal Islam's judgments on the new financial transactions and economic problems.
3. Several writers on Islamic economics limit their studies to subjects that relate essentially to the questions of riba and the prohibiting of interest insurance companies, banking transactions ,as if Islamic economics were limited to these questions. Even in their dealing wit h these topics and in the conclusions of prohibition and unlawfulness that they usually reach (without making any distinction between different banking or insurance operations). most of these writers do not present to us a detailed study on the practical alternative to what they prohibit. This ends up in cutting short the investigation for the required solution.
Some people make the confusion between Islamic economics and Islamic financing science. They entitle their works Islamic economics and inside they deal with the topics of the ‘fifth” (khumus). the “tenth” part (a’ouchour), land-or poll-tax (kharaj) body and face partnerships (sharikat al’abdan and sharikat lwujuh). Although the majority of these topics have acquired historical importance. they nevertheless present no serious studies that can be reliably related to the reality of our modern world.
3.3.3.The Cause of the Problem and it Solution
In the final analysis, the cause of the problem is that we do not have enough specialists in Islamic economics.
There lies, in my opinion. the ill that we are suffering from and there lies too the missing link.
Modern economists lack the thorough knowledge of Islam. and therefore they spontaneously get weary of studying the economic foundations for the economic problems of our time. On the other hand our theologists lack training in modern economics, a fact that makes them unable to do well in revealing the economic foundations of Islam and using them in ways that are consistent with the requirements of our time and with the reality of our current complex economic world.
This state of affairs has led the Moslems of today, common people and leaders alike. to turn in a vicious circle, aspiring to Islamic economics and calling for Islamic solutions to their problems while, at the same time, dividing themselves between the capitalist and the socialist Systems and applying the solutions of this or that system about which they do not feel comfortable or secure.
The only choice for the solution of this problem or the escape from this vicious circle is to train specialists in Islamic economics, who combine “the rich Islamic culture” and “the contemporary modern economic culture".
This will be achieved not through call for determination and appeals to theologists for seeking specialization, but through the creation of departments and chairs for this subject matter in the Islamic universities, administration institutes, faculties of commerce and law, etc. This will lead to the constitution of a specialized student body for this subject matter.
Through this systematic approach, we will highlight the economic foundations of Islam with the spirit of contemporary life, and show the possibility of applying them in a way that is consistent with the changing needs of society. It is only with this approach that we will be able to put an end to all kinds of blind fanaticism and empty appeals, and that we will enable Islamic economics to develop and flourish. and thus contribute to the solution of world problems and the fostering of world peace.
This is a cry from the depth of my heart, which I am addressing to all Moslems, especially the economists and theologists for the sake of knowledge and truth, and for Islam and Moslems, The rationale is that Islamic economics is the material and spiritual strength of Islam, and that it provides the means for the achievement of the Islamic Umma’s cohesion, strength and world mission.
I have conveyed the message. May God be the witness.
http://www.ymsite.com
When departments and chairs are created for Islamic economics, occupants will have numerous difficult responsibilities, especially the following :
1. Preparing studies on Koran and Sunna texts that relate to Islamic economics, showing how these texts can be implemented in ways that are consistent with the conditions of time and space, and suggesting Islamic solutions for the different economic problems of the time.
2. Conducting comparative studies between the Islamic and other economic systems showing the extent to which the differences in their respective applications are a result of differences in the systems themselves, and providing an evaluation of each system.
3. Consulting the volumes written by the experts on Islamic Sharia, extracting their detailed opinions on questions of economics and expressing them in terms used in the current economic literature along with the presentation of relevant commentaries.
4. Keeping abreast of the developments in the economic thought among the Islamic thinkers through out the different Islamic eras and countries, identifying the differences among them, and determining the bases of each opinion and presenting an evaluation of it.
5. Supervising the setting up of a scientific library which contains the volumes research studies, dissertations and specialized journals that deal with economics in Islam.
6. Encouraging the writing of master’s and doctoral dissertations in Islamic economics and providing for the training of young researchers who combine the two cultures the first being one of Islam and Fiqh (Islamic jurisprudence) and the second being one of technical economics.
7. Studying the economic situations in the Islamic world investigating the underdevelopment that it suffers from, and drawing plans for the setting up of Islamic economic structures which will ensure cooperation among Islamic countries and their complementarily, and will benefit humanity.
We are not being unrealistic in our recommendations. We look forward to the setting up within the Islamic world of centers or institutes that are specialized in Islamic economics.
[Note: The First World Conference on Islamic Economics which was convened by the Kingdom of Saudi Arabia and organized by Kint Abdelaziz University in Holy Mecca in Safar 139 February 1976 led to he creation of the World Center for Research on Islamic Economics (as a part of King Abdelaziz University). Similarly. the First World Conference on Fiqh which was convened by the Kingdom of Saudi Arabia and organized by Imam Mohamed Ibn Saoud University in Ryad in Do Lqiada. 1396/November 1976 led to the creation of a department of Islamic Economics in the Sharia faculties. The department is intended for the study of Islamic economics in four complete years and started operating in the academic year 1399-1400 AH. Later this department became a separate Faculty of Islamic Economics. In addition to the above. the Commerce Faculty of the AI-Azhar University took the initiative of setting up the "Sheikh Abdellah Kamil Center for Research and Studies on Islamic Commerce” which delivers, in the name of AI-Azhar University master’s and doctoral degrees in Islamic economics.]
Economy is the vital context which reveals the material and spiritual strength of Islam and through which the Islamic Ummah can achieve its cohesion, strength and universal mission.
3.3. Neglecting the Application of Islamic Economics
3.3.1.Gap between Belief and Reality
Nobody doubts the Moslems’ faith in Islam and nobody questions their belief in the soundness of the principles that constitute the basis of this religion, especially in the context of the organization of society in its political. social and economic activities.
Several voices cry out at different official and non-official levels some die out in insistence while others burst out in anger calling for the application of the foundations and the principles of Islamic economics. Sometimes, these voices find attentive ears and a strong echo among the people in charge as well as a sincere response and a confirmed interest on the part of the peoples and their leaders. However, the response stops there.
3.3.2. The Reasons for not Applying the Principles of Islamic Economics
Although the Moslem peoples and their leaders adhere to Islam and experience the application of the Sharia, they, nonetheless, seek the solutions to their different economic problems outside Islam and thus, we see their societies swinging awkwardly between the capitalist and socialist systems, neglecting their Islamic economic system.
This state of affairs does not mean the forsaking of Islam or doubt about its economic principles. Neither does it mean negligence on the part of Moslems or atavism (reversion) on the part of the leaders. The reason for not applying the principles of Islamic economics is that the solutions which are presented in the name of Islam for the problems of our modern times (and they are complex economic problems) are simplistic and unpractical. In fact these solutions are suggested by some men of religion who are not specialized in economic matters, relying in doing so on some old time religious leaders or theologists. In doing so, they ignore some important matters which are as follows :
1. Islam does not have a place for men of religion as such for all Moslems are men of religion. However, it does have a status for men of knowledge. Nowadays, it is not enough for a person to be educated in the large domain of Fiqh in order to be able to formulate legal opinions about modern complex economic matters. Rather. it is necessary for him, in addition to that, to have a specialized knowledge that comprises the foundations and the details of the economics science.
2. The judgments by Ijtihad made by the old time Islamic leaders and theologists, in spite of their great importance, cannot be taken in their absolute meanings. since they are essentially opinions. Added to this is the fact that most of these judgments were formulated in a period and in conditions which are not ours and on problems which are not ours. Today. We are called upon to make serious attempts as the old time theologists did in order to reveal Islam's judgments on the new financial transactions and economic problems.
3. Several writers on Islamic economics limit their studies to subjects that relate essentially to the questions of riba and the prohibiting of interest insurance companies, banking transactions ,as if Islamic economics were limited to these questions. Even in their dealing wit h these topics and in the conclusions of prohibition and unlawfulness that they usually reach (without making any distinction between different banking or insurance operations). most of these writers do not present to us a detailed study on the practical alternative to what they prohibit. This ends up in cutting short the investigation for the required solution.
Some people make the confusion between Islamic economics and Islamic financing science. They entitle their works Islamic economics and inside they deal with the topics of the ‘fifth” (khumus). the “tenth” part (a’ouchour), land-or poll-tax (kharaj) body and face partnerships (sharikat al’abdan and sharikat lwujuh). Although the majority of these topics have acquired historical importance. they nevertheless present no serious studies that can be reliably related to the reality of our modern world.
3.3.3.The Cause of the Problem and it Solution
In the final analysis, the cause of the problem is that we do not have enough specialists in Islamic economics.
There lies, in my opinion. the ill that we are suffering from and there lies too the missing link.
Modern economists lack the thorough knowledge of Islam. and therefore they spontaneously get weary of studying the economic foundations for the economic problems of our time. On the other hand our theologists lack training in modern economics, a fact that makes them unable to do well in revealing the economic foundations of Islam and using them in ways that are consistent with the requirements of our time and with the reality of our current complex economic world.
This state of affairs has led the Moslems of today, common people and leaders alike. to turn in a vicious circle, aspiring to Islamic economics and calling for Islamic solutions to their problems while, at the same time, dividing themselves between the capitalist and the socialist Systems and applying the solutions of this or that system about which they do not feel comfortable or secure.
The only choice for the solution of this problem or the escape from this vicious circle is to train specialists in Islamic economics, who combine “the rich Islamic culture” and “the contemporary modern economic culture".
This will be achieved not through call for determination and appeals to theologists for seeking specialization, but through the creation of departments and chairs for this subject matter in the Islamic universities, administration institutes, faculties of commerce and law, etc. This will lead to the constitution of a specialized student body for this subject matter.
Through this systematic approach, we will highlight the economic foundations of Islam with the spirit of contemporary life, and show the possibility of applying them in a way that is consistent with the changing needs of society. It is only with this approach that we will be able to put an end to all kinds of blind fanaticism and empty appeals, and that we will enable Islamic economics to develop and flourish. and thus contribute to the solution of world problems and the fostering of world peace.
This is a cry from the depth of my heart, which I am addressing to all Moslems, especially the economists and theologists for the sake of knowledge and truth, and for Islam and Moslems, The rationale is that Islamic economics is the material and spiritual strength of Islam, and that it provides the means for the achievement of the Islamic Umma’s cohesion, strength and world mission.
I have conveyed the message. May God be the witness.
http://www.ymsite.com
Monday, June 1, 2009
Islamic Astronomy (1)
Historians who track the development of astronomy from antiquity to the Renaissance sometimes refer to the time from the eighth through the 14th centuries as the Islamic period. During that interval most astronomical activity took place in the Middle East, North Africa and Moorish Spain. While Europe languished in the Dark Ages, the torch of ancient scholarship had passed into Muslim hands. Islamic scholars kept it alight, and from them it passed to Renaissance Europe.
Two circumstances fostered the growth of astronomy in Islamic lands. One was geographic proximity to the world of ancient learning, coupled with a tolerance for scholars of other creeds. In the ninth century most of the Greek scientific texts were translated into Arabic, including Ptolemy's Syntaxis, the apex of ancient astronomy. It was through these translations that the Greek works later became known in medieval Europe. (Indeed, the Syntaxis is still known primarily by its Arabic name, Almagest, meaning "the greatest.")
The second impetus came from Islamic religious observances, which presented a host of problems in mathematical astronomy, mostly related to timekeeping. In solving these problems the Islamic scholars went far beyond the Greek mathematical methods. These developments, notably in the field of trigonometry, provided the essential tools for the creation of Western Renaissance astronomy.
The traces of medieval Islamic astronomy are conspicuous even today. When an astronomer refers to the zenith, to azimuth or to algebra, or when he mentions the stars in the Summer Triangle--Vega, Altair, Deneb--he is using words of Arabic origin. Yet although the story of how Greek astronomy passed to the Arabs is comparatively well known, the history of its transformation by Islamic scholars and subsequent retransmission to the Latin West is only now being written. Thousands of manuscripts remain unexamined. Nevertheless, it is possible to offer at least a fragmentary sketch of the process.
The House of Wisdom
The foundations of Islamic science in general and of astronomy in particular were laid two centuries after the emigration of the prophet Muhammad from Mecca to Medina in A.D. 622. This event, called the Hegira, marks the beginning of the Islamic calendar. The first centuries of Islam were characterized by a rapid and turbulent expansion. Not until the late second century and early third century of the Hegira era was there a sufficiently stable and cosmopolitan atmosphere in which the sciences could flourish. Then the new Abbasid dynasty, which had taken over the caliphate (the leadership of Islam) in 750 and founded Baghdad as the capital in 762, began to sponsor translations of Greek texts. In just a few decades the major scientific works of antiquity--including those of Galen, Aristotle, Euclid, Ptolemy, Archimedes and Apollonius--were translated into Arabic. The work was done by christian and pagan scholars as well as by Muslims.
The most vigorous patron of this effort was Caliph al-Ma'mun, who acceded to power in 813. Al-Ma'mun founded an academy called the House of Wisdom and placed Hunayn ibn Ishaq al-'Ibadi, a Nestorian Christian with an excellent command of Greek, in charge. Hunayn became the most celebrated of all translators of Greek texts. He produced Arabic versions of Plato, Aristotle and their commentators, and he translated the works of the three founders of Greek medicine, Hippocrates, Galen and Dioscorides.
The academy's principal translator of mathematical and astronomical works was a pagan named Thabit ibn Qurra. Thabit was originally a money changer in the marketplace of Harran, a town in northern Mesopotamia that was the center of an astral cult. He stoutly maintained that the adherents of this cult had first farmed the land, built cities and ports and discovered science, but he was tolerated in the Islamic capital. There he wrote more than 100 scientific treatises, including a commentary on the Almagest.
Another mathematical astronomer at the House of Wisdom was al-Khwarizmi, whose Algebra, dedicated to al-Ma'mun, may well have been the first book on the topic in Arabic. Although it was not particularly impressive as a scientific achievement, it did help to introduce Hindu as well as Greek methods into the Islamic world. Sometime after 1100 it was translated into Latin by an Englishman, Robert of Chester, who had gone to Spain to study mathematics. The translation, beginning with the words "Dicit Algoritmi" (hence the modern word algorithm), had a powerful influence on medieval Western algebra.
Moreover, its influence is still felt in all mathematics and science: it marked the introduction into Europe of "Arabic numerals." Along with certain trigonometric procedures, the Arabs had borrowed from India a system of numbers that included the zero. The Indian numerals existed in two forms in the Islamic world, and it was the Western form that was transmitted through Spain into medieval Europe. These numerals, with the explicit zero, are far more efficient than Roman numerals for making calculations.
Yet another astronomer in ninth-century Baghdad was Ahmad al-Farghani. His most important astronomical work was his Jawami, or Elements, which helped to spread the more elementary and nonmathematical parts of Ptolemy's earth-centered astronomy. The Elements had a considerable influence in the West. It was twice translated into Latin in Toledo, once by John of Seville (Johannes Hispalensis) in the first half of the 12th century, and more completely by Gerard of Cremona a few decades later.
Gerard's translation of al-Farghani provided Dante with his principal knowledge of Ptolemaic astronomy. (In the Divine Comedy the poet ascends through the spheres of the planets, which are centered on the earth.) It was John of Seville's earlier version, however, that became better known in the West. It served as the foundation for the Sphere of Sacrobosco, a still further watered-down account of spherical astronomy written in the early 13th century by John of Holywood (Johannes de Sacrobosco). In universities throughout Western Christendom the Sphere of Sacrobosco became a long-term best seller. In the age of printing it went through more than 200 editions before it was superseded by other textbooks in the early 17th century. With the exception of Euclid's Elements no scientific textbook can claim a longer period of supremacy.
Thus from the House of Wisdom in ancient Baghdad, with its congenial tolerance and its unique blending of cultures, there streamed not only an impressive sequence of translations of Greek scientific and philosophical works but also commentaries and original treatises. By A.D. 900 the foundation had been laid for the full flowering of an international science, with one language--Arabic--as its vehicle.
Religious Impetus
A major impetus for the flowering of astronomy in Islam came from religious observances, which presented an assortment of problems in mathematical astronomy, specifically in spherical geometry.
At the time of Muhammad both Chistians and Jews observed holy days, such as Easter and Passover, whose timing was determined by the phases of the moon. Both communities had confronted the fact that the approximately 29.5-day lunar months are not commensurable with the 365-day solar year: 12 lunar months add up to only 354 days. To solve the problem Christians and Jews had adopted a scheme based on a discovery made in about 430 B.C. by the Athenian astronomer Meton. In the 19-year Metonic cycle there were 12 years of 12 lunar months and seven years of 13 lunar months. The periodic insertion of a 13th month kept calendar dates in step with the seasons.
Apparently, however, not every jurisdiction followed the standard pattern; unscrupulous rulers occasionally added the 13th month when it suited their own interests. To Muhammad this was the work of the devil. In the Koran (chapter 9, verse 36) he decreed that "the number of months in the sight of God is 12 [in a year]--so ordained by Him the day He created the heavens and the earth; of them four are sacred: that is the straight usage." Caliph 'Umar I (634-44) interpreted this decree as requiring a strictly lunar calendar, which to this day is followed in most Islamic countries. Because the Hegira year is about 11 days shorter than the solar year, holidays such as Ramadan, the month of fasting, slowly cycle through the seasons, making their rounds in about 30 solar years.
Furthermore, Ramadan and the other Islamic months do not begin at the astronomical new moon, defined as the time when the moon has the same celestial longitude as the sun and is therefore invisible; instead they begin when the thin crescent moon is first sighted in the western evening sky. Predicting just when the crescent moon would become visible was a special challenge to Islamic mathematical astronomers. Although Ptolemy's theory of the complex lunar motion was tolerably accurate near the time of the new moon, it specified the moon's path only with respect to the ecliptic (the sun's path on the celestial sphere). To predict the first visibility of the moon it was necessary to describe its motion with respect to the horizon, and this problem demanded fairly sophisticated spherical geometry.
Two other religious customs presented problems requiring the application of spherical geometry. One problem, given the requirement for Muslims to pray toward Mecca and to orient their mosques in that direction, was to determine the direction of the holy city from a given location. Another problem was to determine from celestial bodies the proper times for the prayers at sunrise, at midday, in the afternoon, at sunset and in the evening.
Solving any of these problems involves finding the unknown sides or angles of a triangle on the celestial sphere from the known sides and angles way of finding the time of day, for example, is to construct a triangle whose vertexes are the zenith, the north celestial pole and the sun's position. The observer must know the altitude of the sun and that of the pole; the former can be observed, and the latter is equal to the observer's latitude. The time is then given by the angle at the intersection of the meridian (the arc through the zenith and the pole) and the sun's hour circle (the arc through the sun and the pole).
The method Ptolemy used to solve spherical triangles was a clumsy one devised late in the first century by Menelaus of Alexandria. It involved setting up two intersecting right triangles; by applying the Menelaus theorem it was possible to solve for one of the six sides, but only if the other five sides were known. To tell the time from the sun's altitude, for instance, repeated applications of the Menelaus theorem were required. For medieval Islamic astronomers there was an obvious challenge to find a simpler trigonometric method.
By the ninth century the six modern trigonometric functions--sine and cosine, tangent and cotangent, secant and cosecant--had been identified, whereas Ptolemy knew only a single chord function. Of the six, five seem to be essentially Arabic in origin; only the sine function was introduced into Islam from India. (The etymology of the word sine is an interesting tale. The Sanskrit word was ardhajya, meaning "half chord," which in Arabic was shortened and transliterated as jyb. In Arabic vowels are not spelled out, and so the word was read as jayb, meaning "pocket" or "gulf." In medieval Europe it was then translated as sinus, the Latin word for gulf.) From the ninth century onward the development of spherical trigonometry was rapid. Islamic astronomers discovered simple trigonometric identities, such as the law of sines, that made solving spherical triangles a much simpler and quicker process.
by Owen Gingerich.
Scientific American, April 1986 v254 p74(10) COPYRIGHT Scientific American Inc.
Two circumstances fostered the growth of astronomy in Islamic lands. One was geographic proximity to the world of ancient learning, coupled with a tolerance for scholars of other creeds. In the ninth century most of the Greek scientific texts were translated into Arabic, including Ptolemy's Syntaxis, the apex of ancient astronomy. It was through these translations that the Greek works later became known in medieval Europe. (Indeed, the Syntaxis is still known primarily by its Arabic name, Almagest, meaning "the greatest.")
The second impetus came from Islamic religious observances, which presented a host of problems in mathematical astronomy, mostly related to timekeeping. In solving these problems the Islamic scholars went far beyond the Greek mathematical methods. These developments, notably in the field of trigonometry, provided the essential tools for the creation of Western Renaissance astronomy.
The traces of medieval Islamic astronomy are conspicuous even today. When an astronomer refers to the zenith, to azimuth or to algebra, or when he mentions the stars in the Summer Triangle--Vega, Altair, Deneb--he is using words of Arabic origin. Yet although the story of how Greek astronomy passed to the Arabs is comparatively well known, the history of its transformation by Islamic scholars and subsequent retransmission to the Latin West is only now being written. Thousands of manuscripts remain unexamined. Nevertheless, it is possible to offer at least a fragmentary sketch of the process.
The House of Wisdom
The foundations of Islamic science in general and of astronomy in particular were laid two centuries after the emigration of the prophet Muhammad from Mecca to Medina in A.D. 622. This event, called the Hegira, marks the beginning of the Islamic calendar. The first centuries of Islam were characterized by a rapid and turbulent expansion. Not until the late second century and early third century of the Hegira era was there a sufficiently stable and cosmopolitan atmosphere in which the sciences could flourish. Then the new Abbasid dynasty, which had taken over the caliphate (the leadership of Islam) in 750 and founded Baghdad as the capital in 762, began to sponsor translations of Greek texts. In just a few decades the major scientific works of antiquity--including those of Galen, Aristotle, Euclid, Ptolemy, Archimedes and Apollonius--were translated into Arabic. The work was done by christian and pagan scholars as well as by Muslims.
The most vigorous patron of this effort was Caliph al-Ma'mun, who acceded to power in 813. Al-Ma'mun founded an academy called the House of Wisdom and placed Hunayn ibn Ishaq al-'Ibadi, a Nestorian Christian with an excellent command of Greek, in charge. Hunayn became the most celebrated of all translators of Greek texts. He produced Arabic versions of Plato, Aristotle and their commentators, and he translated the works of the three founders of Greek medicine, Hippocrates, Galen and Dioscorides.
The academy's principal translator of mathematical and astronomical works was a pagan named Thabit ibn Qurra. Thabit was originally a money changer in the marketplace of Harran, a town in northern Mesopotamia that was the center of an astral cult. He stoutly maintained that the adherents of this cult had first farmed the land, built cities and ports and discovered science, but he was tolerated in the Islamic capital. There he wrote more than 100 scientific treatises, including a commentary on the Almagest.
Another mathematical astronomer at the House of Wisdom was al-Khwarizmi, whose Algebra, dedicated to al-Ma'mun, may well have been the first book on the topic in Arabic. Although it was not particularly impressive as a scientific achievement, it did help to introduce Hindu as well as Greek methods into the Islamic world. Sometime after 1100 it was translated into Latin by an Englishman, Robert of Chester, who had gone to Spain to study mathematics. The translation, beginning with the words "Dicit Algoritmi" (hence the modern word algorithm), had a powerful influence on medieval Western algebra.
Moreover, its influence is still felt in all mathematics and science: it marked the introduction into Europe of "Arabic numerals." Along with certain trigonometric procedures, the Arabs had borrowed from India a system of numbers that included the zero. The Indian numerals existed in two forms in the Islamic world, and it was the Western form that was transmitted through Spain into medieval Europe. These numerals, with the explicit zero, are far more efficient than Roman numerals for making calculations.
Yet another astronomer in ninth-century Baghdad was Ahmad al-Farghani. His most important astronomical work was his Jawami, or Elements, which helped to spread the more elementary and nonmathematical parts of Ptolemy's earth-centered astronomy. The Elements had a considerable influence in the West. It was twice translated into Latin in Toledo, once by John of Seville (Johannes Hispalensis) in the first half of the 12th century, and more completely by Gerard of Cremona a few decades later.
Gerard's translation of al-Farghani provided Dante with his principal knowledge of Ptolemaic astronomy. (In the Divine Comedy the poet ascends through the spheres of the planets, which are centered on the earth.) It was John of Seville's earlier version, however, that became better known in the West. It served as the foundation for the Sphere of Sacrobosco, a still further watered-down account of spherical astronomy written in the early 13th century by John of Holywood (Johannes de Sacrobosco). In universities throughout Western Christendom the Sphere of Sacrobosco became a long-term best seller. In the age of printing it went through more than 200 editions before it was superseded by other textbooks in the early 17th century. With the exception of Euclid's Elements no scientific textbook can claim a longer period of supremacy.
Thus from the House of Wisdom in ancient Baghdad, with its congenial tolerance and its unique blending of cultures, there streamed not only an impressive sequence of translations of Greek scientific and philosophical works but also commentaries and original treatises. By A.D. 900 the foundation had been laid for the full flowering of an international science, with one language--Arabic--as its vehicle.
Religious Impetus
A major impetus for the flowering of astronomy in Islam came from religious observances, which presented an assortment of problems in mathematical astronomy, specifically in spherical geometry.
At the time of Muhammad both Chistians and Jews observed holy days, such as Easter and Passover, whose timing was determined by the phases of the moon. Both communities had confronted the fact that the approximately 29.5-day lunar months are not commensurable with the 365-day solar year: 12 lunar months add up to only 354 days. To solve the problem Christians and Jews had adopted a scheme based on a discovery made in about 430 B.C. by the Athenian astronomer Meton. In the 19-year Metonic cycle there were 12 years of 12 lunar months and seven years of 13 lunar months. The periodic insertion of a 13th month kept calendar dates in step with the seasons.
Apparently, however, not every jurisdiction followed the standard pattern; unscrupulous rulers occasionally added the 13th month when it suited their own interests. To Muhammad this was the work of the devil. In the Koran (chapter 9, verse 36) he decreed that "the number of months in the sight of God is 12 [in a year]--so ordained by Him the day He created the heavens and the earth; of them four are sacred: that is the straight usage." Caliph 'Umar I (634-44) interpreted this decree as requiring a strictly lunar calendar, which to this day is followed in most Islamic countries. Because the Hegira year is about 11 days shorter than the solar year, holidays such as Ramadan, the month of fasting, slowly cycle through the seasons, making their rounds in about 30 solar years.
Furthermore, Ramadan and the other Islamic months do not begin at the astronomical new moon, defined as the time when the moon has the same celestial longitude as the sun and is therefore invisible; instead they begin when the thin crescent moon is first sighted in the western evening sky. Predicting just when the crescent moon would become visible was a special challenge to Islamic mathematical astronomers. Although Ptolemy's theory of the complex lunar motion was tolerably accurate near the time of the new moon, it specified the moon's path only with respect to the ecliptic (the sun's path on the celestial sphere). To predict the first visibility of the moon it was necessary to describe its motion with respect to the horizon, and this problem demanded fairly sophisticated spherical geometry.
Two other religious customs presented problems requiring the application of spherical geometry. One problem, given the requirement for Muslims to pray toward Mecca and to orient their mosques in that direction, was to determine the direction of the holy city from a given location. Another problem was to determine from celestial bodies the proper times for the prayers at sunrise, at midday, in the afternoon, at sunset and in the evening.
Solving any of these problems involves finding the unknown sides or angles of a triangle on the celestial sphere from the known sides and angles way of finding the time of day, for example, is to construct a triangle whose vertexes are the zenith, the north celestial pole and the sun's position. The observer must know the altitude of the sun and that of the pole; the former can be observed, and the latter is equal to the observer's latitude. The time is then given by the angle at the intersection of the meridian (the arc through the zenith and the pole) and the sun's hour circle (the arc through the sun and the pole).
The method Ptolemy used to solve spherical triangles was a clumsy one devised late in the first century by Menelaus of Alexandria. It involved setting up two intersecting right triangles; by applying the Menelaus theorem it was possible to solve for one of the six sides, but only if the other five sides were known. To tell the time from the sun's altitude, for instance, repeated applications of the Menelaus theorem were required. For medieval Islamic astronomers there was an obvious challenge to find a simpler trigonometric method.
By the ninth century the six modern trigonometric functions--sine and cosine, tangent and cotangent, secant and cosecant--had been identified, whereas Ptolemy knew only a single chord function. Of the six, five seem to be essentially Arabic in origin; only the sine function was introduced into Islam from India. (The etymology of the word sine is an interesting tale. The Sanskrit word was ardhajya, meaning "half chord," which in Arabic was shortened and transliterated as jyb. In Arabic vowels are not spelled out, and so the word was read as jayb, meaning "pocket" or "gulf." In medieval Europe it was then translated as sinus, the Latin word for gulf.) From the ninth century onward the development of spherical trigonometry was rapid. Islamic astronomers discovered simple trigonometric identities, such as the law of sines, that made solving spherical triangles a much simpler and quicker process.
by Owen Gingerich.
Scientific American, April 1986 v254 p74(10) COPYRIGHT Scientific American Inc.
Islamic Astronomy (2)
Stars and Astrolabes
One of the most conspicuous examples of modern astronomy's Islamic heritage is the names of stars. Betelgeuse, Rigel, Vega, Aldebaran and Fomalhaut are among the names that are directly Arabic in origin or are Arabic translations of Ptolemy's Greek descriptions.
In the Almagest Ptolemy had provided a catalogue of more than 1,000 stars. The first critical revision of the catalogue was compiled by 'Abd al-Rahman al-Sufi, a 10th-century Persian astronomer who worked in both Iran and Baghdad. Al-Sufi's Kitab su-war al-kawakib ("Book on the Constellations of Fixed Stars") did not add or subtract stars from the Almagest list, nor did it remeasure their often faulty positions, but it did give improved magnitudes as well as Arabic identifications. The latter were mostly just translations of Ptolemy.
For many years it was assumed that al-Sufi's Arabic had established the stellar nomenclature in the West. It now seems that his 14th- and 15th-century Latin translators went to a Latin version of the Arabic edition of Ptolemy himself for the star descriptions, which they combined with al-Sufi's splendid pictorial representations of the constellations. Meanwhile the Arabic star nomenclature trickled into the West by another route: the making of astrolabes.
The astrolabe was a Greek invention. Essentially it is a two-dimensional model of the sky, an analog computer for solving the problems of spherical astronomy [see "The Astrolabe," by J. D. North; SCIENTIFIC AMERICAN, January, 1974]. A typical astrolabe consists of a series of brass plates nested in a brass matrix known in Arabic as the umm (meaning "womb"). The uppermost plate, called the 'ankabut (meaning "spider") or in Latin the rete, is an open network of two or three dozen pointers indicating the position of specific stars. Under the rete are one or more solid plates, each engraved with a celestial coordinate system appropriate for observations at a particular latitude: circles of equal altitude above the horizon (analogous to terrestrial latitude lines) and circles of equal azimuth around the horizon (analogous to longitude lines). By rotating the rete about a central pin, which represents the north celestial pole, the daily motions of the stars on the celestial sphere can be reproduced.
Although the astrolabe was known in antiquity, the earliest dated instrument that has been preserved comes from the Islamic period [see cover of this issue]. It was made by one Nastulus in 315 of the Hegira era (A.D. 927-28), and it is now one of the treasures of the Kuwait National Museum. Only a handful of 10th-century Arabic astrolabes exist, whereas nearly 40 have survived from the 11th and 12th centuries. Several of these were made in Spain in the mid-11th century and have a distinctly Moorish style.
The earliest extant Arabic treatise on the astrolabe was written in Baghdad by one of Caliph al-Ma'mun's astronomers, 'Ali ibn 'Isa. Later members of the Baghdad school, notably al-Farghani, also wrote on the astrolabe. Al-Farghani's treatise was impressive for the mathematical way he applied the instrument to problems in astrology, astronomy and timekeeping.
Many of these treatises found their way to Spain, where they were translated into Latin in the 12th and 13th centuries. The most popular work, which exists today in about 200 Latin manuscript copies, was long mistakenly attributed to Masha'allah, a Jewish astronomer of the eighth century who participated in the decision to found Baghdad; it probably is a later pastiche from a variety of sources. In about 1390 this treatise was the basis for an essay on the astrolabe by the English poet Geoffrey Chaucer. Indeed, England seems to have been the gateway for the introduction of the astrolabe from Spain into Western Christendom in the late 13th and 14th centuries. It is possible that scientific activity centered at Oxford at the time contributed to the surge of interest in the device. Merton and Oriel colleges of the University of Oxford still own fine 14th-century astrolabes.
On them one finds typical sets of Arabic star names written in Gothic Latin letters. Included on the Merton College astrolabe, for example, are Arabic names that have evolved into standard modern nomenclature: Wega, Altahir, Algeuze, Rigil, Elfeta, Alferaz and Mirac. Thus as a result of the astrolabe tradition of Eastern Islam, transmitted through Spain to England, most navigational stars today have Arabic names, either indigenous ones or Arabic translations of Ptolemy's Greek descriptions.
Refining Ptolemy
It would be wrong to conclude from the preponderance of Arabic star names that Islamic astronomers made exhaustive studies of the sky. On the contrary, their observations were quite limited. For instance, the spectacular supernova (stellar explosion) of 1054, which produced the Crab Nebula, went virtually unrecorded in Islamic texts even though it was widely noted in China. Modern astronomers struck by this glaring gap often do not realize that Islamic astronomers failed to document most specific astronomical phenomena. They had little incentive to do so. Their astrology, unlike that of the Chinese, depended not so much on unusual heavenly omens as on planetary positions, and these were quite well described by the Ptolemaic procedures.
The planetary models that Ptolemy devised in the second century A.D. had the sun, the moon and the planets moving around the earth. A simple circular orbit, however, could not account for the fact that a planet periodically seems to reverse its direction of motion across the sky. (According to the modern heliocentric viewpoint, this apparent retrograde motion occurs when the earth is passing or being passed by another planet on its way around the sun.) Hence Ptolemy had each planet moving on an epicycle, a rotating circle whose center moved about the earth on a larger circle called the deferent. The epicycle, together with other geometric devices invented by Ptolemy, gave a fairly good first approximation to the apparent motion of the planets. As a great theoretician, Ptolemy must have been fairly confident of the particular geometry of his models, since he never described how he settled on it.
On the other hand, the idea of applying mathematics to a specific numerical description of the physical world was something rather novel for the Hellenistic Greeks, quite different from the pure mathematics of Euclid and Apollonius. In this part of his program Ptolemy must have realized that improved values for the numerical parameters of his models were both desirable and inevitable, and so he gave careful instructions on how to establish the parameters from a limited number of selected observations. The Islamic astronomers learned this lesson all too well. They limited their observations, or at least the few they chose to record, primarily to measurements that could be used for rederiving key parameters. These included the orientation and eccentricity of the solar orbit and the inclination of the ecliptic plane.
An impressive example of an Islamic astronomer working strictly within a Ptolemaic framework but establishing new values for Ptolemy's parameters was Muhammad al-Battani, a younger contemporary of Thabit ibn Qurra. Al-Battani's Zij ("Astronomical Tables") is still admired as one of the most important astronomical works between the time of Ptolemy and that of Copernicus. Among other things, al-Battani was able to establish the position of the solar orbit (equivalent in modern terms to finding the position of the earth's orbit) with better success than Ptolemy had achieved.
Because al-Battani does not describe his observations in detail, it is not clear whether he adopted an observational strategy different from that of Ptolemy. In any case his results were good, and centuries later his parameters for the solar orbit were widely known in Europe. His Zij first made its way to Spain. There it was translated into Latin early in the 12th century and into Castilian a little more than 100 years later. The fact that only a single Arabic manuscript copy survives (in the Escorial Library near Madrid) suggests that al-Battani's astronomy was not as highly regarded in Islam as it was in Europe, where the advent of printing ensured its survival and in particular made it available to Copernicus and his contemporaries. In De revolutionibus orbium coelestium ("On the Revolutions of the Heavenly Spheres") the Polish astronomer mentions his ninth-century Muslim predecessor no fewer than 23 times.
In contrast, one of the greatest astronomers of medieval Islam, 'Ali ibn 'Abd al-Rahman ibn Yunus, remained completely unknown to European astronomers of the Renaissance. Working in Cairo a century after al-Battani, Ibn Yunus wrote a major astronomical handbook called the Hakimi Zij. Unlike other Arabic astronomers, he prefaced his Zij with a series of more than 100 observations, mostly of eclipses and planetary conjunctions. Although Ibn Yunus' handbook was widely used in Islam, and his timekeeping tables survived in use in Cairo into the 19th century, his work became known in the West less than 200 years ago.
Throughout the entire Islamic period astronomers stayed securely within the geocentric framework. For this one should not criticize them too harshly. Until Galileo's telescopic observations of the phases of Venus in 1610, no observational evidence could be brought against the Ptolemaic system. Even Galileo's observations could not distinguish between the geo-heliocentric system of Tycho Brahe (in which the other planets revolved about the sun but the sun revolved about the earth) and the purely heliocentric system of Copernicus [see "The Galileo Affair," by Owen Gingerich; SCIENTIFIC AMERICAN, August, 1982]. Furthermore, although Islamic astronomers followed Ptolemy's injunction to test his results, they did not limit themselves simply to improving his parameters. The technical details of his models were not immune from criticism. These attacks, however, were invariably launched on philosophical rather than on observational grounds.
by Owen Gingerich.
Scientific American, April 1986 v254 p74(10) COPYRIGHT Scientific American Inc.
One of the most conspicuous examples of modern astronomy's Islamic heritage is the names of stars. Betelgeuse, Rigel, Vega, Aldebaran and Fomalhaut are among the names that are directly Arabic in origin or are Arabic translations of Ptolemy's Greek descriptions.
In the Almagest Ptolemy had provided a catalogue of more than 1,000 stars. The first critical revision of the catalogue was compiled by 'Abd al-Rahman al-Sufi, a 10th-century Persian astronomer who worked in both Iran and Baghdad. Al-Sufi's Kitab su-war al-kawakib ("Book on the Constellations of Fixed Stars") did not add or subtract stars from the Almagest list, nor did it remeasure their often faulty positions, but it did give improved magnitudes as well as Arabic identifications. The latter were mostly just translations of Ptolemy.
For many years it was assumed that al-Sufi's Arabic had established the stellar nomenclature in the West. It now seems that his 14th- and 15th-century Latin translators went to a Latin version of the Arabic edition of Ptolemy himself for the star descriptions, which they combined with al-Sufi's splendid pictorial representations of the constellations. Meanwhile the Arabic star nomenclature trickled into the West by another route: the making of astrolabes.
The astrolabe was a Greek invention. Essentially it is a two-dimensional model of the sky, an analog computer for solving the problems of spherical astronomy [see "The Astrolabe," by J. D. North; SCIENTIFIC AMERICAN, January, 1974]. A typical astrolabe consists of a series of brass plates nested in a brass matrix known in Arabic as the umm (meaning "womb"). The uppermost plate, called the 'ankabut (meaning "spider") or in Latin the rete, is an open network of two or three dozen pointers indicating the position of specific stars. Under the rete are one or more solid plates, each engraved with a celestial coordinate system appropriate for observations at a particular latitude: circles of equal altitude above the horizon (analogous to terrestrial latitude lines) and circles of equal azimuth around the horizon (analogous to longitude lines). By rotating the rete about a central pin, which represents the north celestial pole, the daily motions of the stars on the celestial sphere can be reproduced.
Although the astrolabe was known in antiquity, the earliest dated instrument that has been preserved comes from the Islamic period [see cover of this issue]. It was made by one Nastulus in 315 of the Hegira era (A.D. 927-28), and it is now one of the treasures of the Kuwait National Museum. Only a handful of 10th-century Arabic astrolabes exist, whereas nearly 40 have survived from the 11th and 12th centuries. Several of these were made in Spain in the mid-11th century and have a distinctly Moorish style.
The earliest extant Arabic treatise on the astrolabe was written in Baghdad by one of Caliph al-Ma'mun's astronomers, 'Ali ibn 'Isa. Later members of the Baghdad school, notably al-Farghani, also wrote on the astrolabe. Al-Farghani's treatise was impressive for the mathematical way he applied the instrument to problems in astrology, astronomy and timekeeping.
Many of these treatises found their way to Spain, where they were translated into Latin in the 12th and 13th centuries. The most popular work, which exists today in about 200 Latin manuscript copies, was long mistakenly attributed to Masha'allah, a Jewish astronomer of the eighth century who participated in the decision to found Baghdad; it probably is a later pastiche from a variety of sources. In about 1390 this treatise was the basis for an essay on the astrolabe by the English poet Geoffrey Chaucer. Indeed, England seems to have been the gateway for the introduction of the astrolabe from Spain into Western Christendom in the late 13th and 14th centuries. It is possible that scientific activity centered at Oxford at the time contributed to the surge of interest in the device. Merton and Oriel colleges of the University of Oxford still own fine 14th-century astrolabes.
On them one finds typical sets of Arabic star names written in Gothic Latin letters. Included on the Merton College astrolabe, for example, are Arabic names that have evolved into standard modern nomenclature: Wega, Altahir, Algeuze, Rigil, Elfeta, Alferaz and Mirac. Thus as a result of the astrolabe tradition of Eastern Islam, transmitted through Spain to England, most navigational stars today have Arabic names, either indigenous ones or Arabic translations of Ptolemy's Greek descriptions.
Refining Ptolemy
It would be wrong to conclude from the preponderance of Arabic star names that Islamic astronomers made exhaustive studies of the sky. On the contrary, their observations were quite limited. For instance, the spectacular supernova (stellar explosion) of 1054, which produced the Crab Nebula, went virtually unrecorded in Islamic texts even though it was widely noted in China. Modern astronomers struck by this glaring gap often do not realize that Islamic astronomers failed to document most specific astronomical phenomena. They had little incentive to do so. Their astrology, unlike that of the Chinese, depended not so much on unusual heavenly omens as on planetary positions, and these were quite well described by the Ptolemaic procedures.
The planetary models that Ptolemy devised in the second century A.D. had the sun, the moon and the planets moving around the earth. A simple circular orbit, however, could not account for the fact that a planet periodically seems to reverse its direction of motion across the sky. (According to the modern heliocentric viewpoint, this apparent retrograde motion occurs when the earth is passing or being passed by another planet on its way around the sun.) Hence Ptolemy had each planet moving on an epicycle, a rotating circle whose center moved about the earth on a larger circle called the deferent. The epicycle, together with other geometric devices invented by Ptolemy, gave a fairly good first approximation to the apparent motion of the planets. As a great theoretician, Ptolemy must have been fairly confident of the particular geometry of his models, since he never described how he settled on it.
On the other hand, the idea of applying mathematics to a specific numerical description of the physical world was something rather novel for the Hellenistic Greeks, quite different from the pure mathematics of Euclid and Apollonius. In this part of his program Ptolemy must have realized that improved values for the numerical parameters of his models were both desirable and inevitable, and so he gave careful instructions on how to establish the parameters from a limited number of selected observations. The Islamic astronomers learned this lesson all too well. They limited their observations, or at least the few they chose to record, primarily to measurements that could be used for rederiving key parameters. These included the orientation and eccentricity of the solar orbit and the inclination of the ecliptic plane.
An impressive example of an Islamic astronomer working strictly within a Ptolemaic framework but establishing new values for Ptolemy's parameters was Muhammad al-Battani, a younger contemporary of Thabit ibn Qurra. Al-Battani's Zij ("Astronomical Tables") is still admired as one of the most important astronomical works between the time of Ptolemy and that of Copernicus. Among other things, al-Battani was able to establish the position of the solar orbit (equivalent in modern terms to finding the position of the earth's orbit) with better success than Ptolemy had achieved.
Because al-Battani does not describe his observations in detail, it is not clear whether he adopted an observational strategy different from that of Ptolemy. In any case his results were good, and centuries later his parameters for the solar orbit were widely known in Europe. His Zij first made its way to Spain. There it was translated into Latin early in the 12th century and into Castilian a little more than 100 years later. The fact that only a single Arabic manuscript copy survives (in the Escorial Library near Madrid) suggests that al-Battani's astronomy was not as highly regarded in Islam as it was in Europe, where the advent of printing ensured its survival and in particular made it available to Copernicus and his contemporaries. In De revolutionibus orbium coelestium ("On the Revolutions of the Heavenly Spheres") the Polish astronomer mentions his ninth-century Muslim predecessor no fewer than 23 times.
In contrast, one of the greatest astronomers of medieval Islam, 'Ali ibn 'Abd al-Rahman ibn Yunus, remained completely unknown to European astronomers of the Renaissance. Working in Cairo a century after al-Battani, Ibn Yunus wrote a major astronomical handbook called the Hakimi Zij. Unlike other Arabic astronomers, he prefaced his Zij with a series of more than 100 observations, mostly of eclipses and planetary conjunctions. Although Ibn Yunus' handbook was widely used in Islam, and his timekeeping tables survived in use in Cairo into the 19th century, his work became known in the West less than 200 years ago.
Throughout the entire Islamic period astronomers stayed securely within the geocentric framework. For this one should not criticize them too harshly. Until Galileo's telescopic observations of the phases of Venus in 1610, no observational evidence could be brought against the Ptolemaic system. Even Galileo's observations could not distinguish between the geo-heliocentric system of Tycho Brahe (in which the other planets revolved about the sun but the sun revolved about the earth) and the purely heliocentric system of Copernicus [see "The Galileo Affair," by Owen Gingerich; SCIENTIFIC AMERICAN, August, 1982]. Furthermore, although Islamic astronomers followed Ptolemy's injunction to test his results, they did not limit themselves simply to improving his parameters. The technical details of his models were not immune from criticism. These attacks, however, were invariably launched on philosophical rather than on observational grounds.
by Owen Gingerich.
Scientific American, April 1986 v254 p74(10) COPYRIGHT Scientific American Inc.
Islamic Astronomy (3)
Doubting Ptolemy
Ptolemy's models were essentially a mathematical system for predicting the positions of the planets. Yet in the Planetary Hypotheses he did try to fit the models into a cosmological system, the Aristotelian scheme of tightly nested spheres centered on the earth. He placed the nearest point of Mercury's path immediately beyond the most distant point of the moon's path; immediately beyond the farthest excursion of Mercury lay the nearest approach of Venus, and so on through the spheres for the sun, Mars, Jupiter and Saturn.
To reproduce the observed nonuniform motions of the planets, however, Ptolemy adopted two purely geometric devices in addition to the epicycle. First, he placed the deferent circles off-center with respect to the earth. Second, he made the ingenious assumption that the motion of celestial bodies was uniform not around the earth, nor around the centers of their deferents, but instead around a point called the equant that was opposite the earth from the deferent center and at an equal distance. Eccentric deferents and equants did a good job of representing the varying speeds with which planets are seen to move across the sky, but to some minds they were philosophically offensive.
The equant in particular was objectionable to philosophers who thought of planetary spheres as real physical objects, each sphere driven by the one outside it (and the outermost driven by the prime mover), and who wanted to be able to construct a mechanical model of the system. For example, as was pointed out by Maimonides, a Jewish scholar of the 12th century who worked in Spain and Cairo, the equant point for Saturn fell right on the spheres for Mercury. This was clearly awkward from a mechanical point of view. Furthermore, the equant violated the philosophical notion that heavenly bodies should be moved by a system of perfect circles, each of which rotated with uniform angular velocity about its center. To some purists even Ptolemy's eccentric deferents, which moved the earth away from the center of things, were philosophically unsatisfactory.
The Islamic astronomers adopted the Ptolemaic-Aristotelian cosmology, but eventually criticism emerged. One of the first critics was Ibn al-Haytham (Alhazen), a leading physicist of 11th-century Cairo. In his Doubts on Ptolemy he complained that the equant failed to satisfy the requirement of uniform circular motion, and he went so far as to declare the planetary models of the Almagest false.
Only one of Ibn al-Haytham's astronomical works, a book called On the Configuration of the World, penetrated into Latin Europe in the Middle Ages. In it he attempted to discover the physical reality underlying Ptolemy's mathematical models. Conceiving of the heavens in terms of concentric spheres and shells, he tried to assign a single spherical body to each of the Almagest's simple motions. The work was translated into Castilian in the court of Alfonso the Wise, and early in the 14th century from Castilian into Latin. Either this version or a Latin translation of one of Ibn al-Haytham's popularizers had a major influence in early Renaissance Europe. The concept of separate celestial spheres for each component of Ptolemy's planetary motions gained wide currency through a textbook, Theorica novae planetarum, written by the Viennese Georg Peurbach in about 1454.
Meanwhile, in the 12th century in the western Islamic region of Andalusia, the astronomer and philosopher Ibn Rushd (Averroes) gradually developed a somewhat more extreme criticism of Ptolemy. "To assert the existence of an eccentric sphere or an epicyclic sphere is contrary to nature...," he wrote. "The astronomy of our time offers no truth, but only agrees with the calculations and not with what exists." Averroes rejected Ptolemy's eccentric deferents and argued for a strictly concentric model of the universe.
An Andalusian comtemporary, Abu Ishaq al-Bitruji, actually tried to formulate such a strictly geocentric model. The results were disastrous. For example, in al-Bitruji's system Saturn could on occasion deviate from the ecliptic by as much as 26 degrees (instead of the required three degrees). As for the observed motions that led Ptolemy to propose the equant, they were completely ignored. In the words of one modern commentator, al-Bitruji "heaps chaos on confusion." Nevertheless, early in the 13th century his work was translated into Latin under the name Alpetragius, and from about 1230 on his ideas were widely discussed throughout Europe. Even Copernicus cited his order of the planets, which placed Venus beyond the sun.
At the other end of the Islamic world a fresh critique of the Ptolemaic mechanisms was undertaken in the 13th century by Nasir al-Din al-Tusi. One of the most prolific Islamic polymaths, with 150 known treatises and letters to his credit, al-Tusi also constructed a major observatory at Maragha (the present-day Maragheh in Iran).
Al-Tusi found the equant particularly dissatisfactory. In his Tadhkira ("Memorandum") he replaced it by adding two more small epicycles to the model of each planet's orbit. Through this ingenious device al-Tusi was able to achieve his goal of generating the nonuniform motions of the planets by combinations of uniformly rotating circles. The centers of the deferents, however, were still displaced from the earth. Two other astronomers at the Maragha observatory, Mu'ayyad al-Din al-'Urdi and Qutb al-Din al-Shirazi, offered an alternative arrangement, but this system too retained the philosophically objectionable eccentricity.
Finally a completely concentric rearrangement of the planetary mechanisms was achieved by Ibn al-Shatir, who worked in Damascus in about 1350. By using a scheme related to that of al-Tusi, Ibn al-Shatir succeeded in eliminating not only the equant but also certain other objectionable circles from Ptolemy's constructions. He thereby cleared the way for a perfectly nested and mechanically acceptable set of celestial spheres. (He described his work thus: "I found that the most distinguished of the later astronomers had adduced indisputable doubts concerning the well-known astronomy of the spheres according to Ptolemy. I therefore asked Almighty God to give me inspiration and help me to invent models that would achieve what was required, and God--may He be praised and exalted--did enable me to devise universal models for the planetary motions in longitude and latitude and all other observable features of their motions, models that were free from the doubts surrounding previous ones.") Yet Ibn al-Shatir's solution, along with the work of the Maragha astronomers, remained generally unknown in medieval Europe.
Influence on Copernicus?
Ibn al-Shatir's forgotten model was rediscovered in the late 1950's by E. S. Kennedy and his students at the American University of Beirut. The discovery raised an intriguing question. It was quickly recognized that the Ibn al-Shatir and Maragha inventions were the same type of mechanism used by Copernicus a few centuries later to eliminate the equant and to generate the intricate changes in the position of the earth's orbit. Copernicus, of course, adopted a heliocentric arrangement, but the problem of accounting for the slow but regular changes in a planet's orbital speed remained exactly the same. Since Copernicus agreed with the philosophical objections to the equant--like some of his Islamic predecessors, he apparently believed celestial motions were driven by physical, crystalline spheres--he too sought to replace Ptolemy's device. In a preliminary work, the Commentariolus, he employed an arrangement equivalent to Ibn al-Shatir's. Later, in De revolutionibus, he reverted to the use of eccentric orbits, adopting a model that was the sun-centered equivalent of the one developed at Maragha.
Could Copernicus have been influenced by the Maragha astronomers or by Ibn al-Shatir? No Latin translation has been found of any of their works or indeed of any work describing their models. It is conceivable that Copernicus saw an Arabic manuscript while he was studying in Italy (from 1496 to 1503) and had it translated, but this seems highly improbable. A Greek translation of some of the al-Tusi material is known to have reached Rome in the 15th century (many Greek manuscripts were carried west after the fall of Constantinople in 1453), but there is no evidence that Copernicus ever saw it.
Scholars are currently divided over whether Copernicus got his method for replacing the equant by some unknown route from the Islamic world or whether he found it on his own. I personally believe he could have invented the method independently.
Nevertheless, the whole idea of criticizing Ptolemy and eliminating the equant is part of the climate of opinion inherited by the Latin West from Islam. The Islamic astronomers would probably have been astonished and even horrified by the revolution started by Copernicus. Yet his motives were not completely different from theirs. In eliminating the equant, and even in placing the planets in orbit around the sun, Copernicus was in part trying to formulate a mechanically functional system, one that offered not only a mathematical representation but also a physical explanation of planetary motions. In a profound sense he was simply working out the implications of an astronomy founded by Ptolemy but transformed by the Islamic astronomers. Today that heritage belongs to the entire world of science.
by Owen Gingerich.
Scientific American, April 1986 v254 p74(10) COPYRIGHT Scientific American Inc.
Ptolemy's models were essentially a mathematical system for predicting the positions of the planets. Yet in the Planetary Hypotheses he did try to fit the models into a cosmological system, the Aristotelian scheme of tightly nested spheres centered on the earth. He placed the nearest point of Mercury's path immediately beyond the most distant point of the moon's path; immediately beyond the farthest excursion of Mercury lay the nearest approach of Venus, and so on through the spheres for the sun, Mars, Jupiter and Saturn.
To reproduce the observed nonuniform motions of the planets, however, Ptolemy adopted two purely geometric devices in addition to the epicycle. First, he placed the deferent circles off-center with respect to the earth. Second, he made the ingenious assumption that the motion of celestial bodies was uniform not around the earth, nor around the centers of their deferents, but instead around a point called the equant that was opposite the earth from the deferent center and at an equal distance. Eccentric deferents and equants did a good job of representing the varying speeds with which planets are seen to move across the sky, but to some minds they were philosophically offensive.
The equant in particular was objectionable to philosophers who thought of planetary spheres as real physical objects, each sphere driven by the one outside it (and the outermost driven by the prime mover), and who wanted to be able to construct a mechanical model of the system. For example, as was pointed out by Maimonides, a Jewish scholar of the 12th century who worked in Spain and Cairo, the equant point for Saturn fell right on the spheres for Mercury. This was clearly awkward from a mechanical point of view. Furthermore, the equant violated the philosophical notion that heavenly bodies should be moved by a system of perfect circles, each of which rotated with uniform angular velocity about its center. To some purists even Ptolemy's eccentric deferents, which moved the earth away from the center of things, were philosophically unsatisfactory.
The Islamic astronomers adopted the Ptolemaic-Aristotelian cosmology, but eventually criticism emerged. One of the first critics was Ibn al-Haytham (Alhazen), a leading physicist of 11th-century Cairo. In his Doubts on Ptolemy he complained that the equant failed to satisfy the requirement of uniform circular motion, and he went so far as to declare the planetary models of the Almagest false.
Only one of Ibn al-Haytham's astronomical works, a book called On the Configuration of the World, penetrated into Latin Europe in the Middle Ages. In it he attempted to discover the physical reality underlying Ptolemy's mathematical models. Conceiving of the heavens in terms of concentric spheres and shells, he tried to assign a single spherical body to each of the Almagest's simple motions. The work was translated into Castilian in the court of Alfonso the Wise, and early in the 14th century from Castilian into Latin. Either this version or a Latin translation of one of Ibn al-Haytham's popularizers had a major influence in early Renaissance Europe. The concept of separate celestial spheres for each component of Ptolemy's planetary motions gained wide currency through a textbook, Theorica novae planetarum, written by the Viennese Georg Peurbach in about 1454.
Meanwhile, in the 12th century in the western Islamic region of Andalusia, the astronomer and philosopher Ibn Rushd (Averroes) gradually developed a somewhat more extreme criticism of Ptolemy. "To assert the existence of an eccentric sphere or an epicyclic sphere is contrary to nature...," he wrote. "The astronomy of our time offers no truth, but only agrees with the calculations and not with what exists." Averroes rejected Ptolemy's eccentric deferents and argued for a strictly concentric model of the universe.
An Andalusian comtemporary, Abu Ishaq al-Bitruji, actually tried to formulate such a strictly geocentric model. The results were disastrous. For example, in al-Bitruji's system Saturn could on occasion deviate from the ecliptic by as much as 26 degrees (instead of the required three degrees). As for the observed motions that led Ptolemy to propose the equant, they were completely ignored. In the words of one modern commentator, al-Bitruji "heaps chaos on confusion." Nevertheless, early in the 13th century his work was translated into Latin under the name Alpetragius, and from about 1230 on his ideas were widely discussed throughout Europe. Even Copernicus cited his order of the planets, which placed Venus beyond the sun.
At the other end of the Islamic world a fresh critique of the Ptolemaic mechanisms was undertaken in the 13th century by Nasir al-Din al-Tusi. One of the most prolific Islamic polymaths, with 150 known treatises and letters to his credit, al-Tusi also constructed a major observatory at Maragha (the present-day Maragheh in Iran).
Al-Tusi found the equant particularly dissatisfactory. In his Tadhkira ("Memorandum") he replaced it by adding two more small epicycles to the model of each planet's orbit. Through this ingenious device al-Tusi was able to achieve his goal of generating the nonuniform motions of the planets by combinations of uniformly rotating circles. The centers of the deferents, however, were still displaced from the earth. Two other astronomers at the Maragha observatory, Mu'ayyad al-Din al-'Urdi and Qutb al-Din al-Shirazi, offered an alternative arrangement, but this system too retained the philosophically objectionable eccentricity.
Finally a completely concentric rearrangement of the planetary mechanisms was achieved by Ibn al-Shatir, who worked in Damascus in about 1350. By using a scheme related to that of al-Tusi, Ibn al-Shatir succeeded in eliminating not only the equant but also certain other objectionable circles from Ptolemy's constructions. He thereby cleared the way for a perfectly nested and mechanically acceptable set of celestial spheres. (He described his work thus: "I found that the most distinguished of the later astronomers had adduced indisputable doubts concerning the well-known astronomy of the spheres according to Ptolemy. I therefore asked Almighty God to give me inspiration and help me to invent models that would achieve what was required, and God--may He be praised and exalted--did enable me to devise universal models for the planetary motions in longitude and latitude and all other observable features of their motions, models that were free from the doubts surrounding previous ones.") Yet Ibn al-Shatir's solution, along with the work of the Maragha astronomers, remained generally unknown in medieval Europe.
Influence on Copernicus?
Ibn al-Shatir's forgotten model was rediscovered in the late 1950's by E. S. Kennedy and his students at the American University of Beirut. The discovery raised an intriguing question. It was quickly recognized that the Ibn al-Shatir and Maragha inventions were the same type of mechanism used by Copernicus a few centuries later to eliminate the equant and to generate the intricate changes in the position of the earth's orbit. Copernicus, of course, adopted a heliocentric arrangement, but the problem of accounting for the slow but regular changes in a planet's orbital speed remained exactly the same. Since Copernicus agreed with the philosophical objections to the equant--like some of his Islamic predecessors, he apparently believed celestial motions were driven by physical, crystalline spheres--he too sought to replace Ptolemy's device. In a preliminary work, the Commentariolus, he employed an arrangement equivalent to Ibn al-Shatir's. Later, in De revolutionibus, he reverted to the use of eccentric orbits, adopting a model that was the sun-centered equivalent of the one developed at Maragha.
Could Copernicus have been influenced by the Maragha astronomers or by Ibn al-Shatir? No Latin translation has been found of any of their works or indeed of any work describing their models. It is conceivable that Copernicus saw an Arabic manuscript while he was studying in Italy (from 1496 to 1503) and had it translated, but this seems highly improbable. A Greek translation of some of the al-Tusi material is known to have reached Rome in the 15th century (many Greek manuscripts were carried west after the fall of Constantinople in 1453), but there is no evidence that Copernicus ever saw it.
Scholars are currently divided over whether Copernicus got his method for replacing the equant by some unknown route from the Islamic world or whether he found it on his own. I personally believe he could have invented the method independently.
Nevertheless, the whole idea of criticizing Ptolemy and eliminating the equant is part of the climate of opinion inherited by the Latin West from Islam. The Islamic astronomers would probably have been astonished and even horrified by the revolution started by Copernicus. Yet his motives were not completely different from theirs. In eliminating the equant, and even in placing the planets in orbit around the sun, Copernicus was in part trying to formulate a mechanically functional system, one that offered not only a mathematical representation but also a physical explanation of planetary motions. In a profound sense he was simply working out the implications of an astronomy founded by Ptolemy but transformed by the Islamic astronomers. Today that heritage belongs to the entire world of science.
by Owen Gingerich.
Scientific American, April 1986 v254 p74(10) COPYRIGHT Scientific American Inc.
Friday, March 27, 2009
The Solar System
"He is the Creator of the Heavens and the Earth..." (Surat ash-Shura, 11)
The solar system is one of the most wonderful examples of this beautiful harmony to be witnessed. There are nine planets with fifty-four known satellites and an unknown number of smaller bodies. The major planets counting outward from the sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Earth is the only one on which life is known to exist. It is surely the only one on which human beings can live and survive unaided thanks to abundant land and water and to a breathable atmosphere.
In the structure of the solar system, we encounter another beautiful example of equilibrium: the balance between a planet's centrifugal force countered by the gravitational attraction of its primary. (In astronomy, a primary is something that another body revolves about. Earth's primary is the sun; the moon's primary is Earth.) Without this balance, everything in the solar system would fly off into the chilling depths of outer space. The balance between these two forces results in paths (orbits) that the planets and other bodies follow around their primaries. If a body moved at too slow a speed, it would plunge into the primary; if it moved at too fast a speed, the primary would be unable to hold onto it, and it would fly off into space. Instead, every body moves at just the right speed to keep it in orbit. Moreover, this equilibrium has to be different for each body because the distance of planets to the sun differs. So do their masses. Therefore, they have to have different orbital speeds not to plunge into the sun or not to fly off into space.
Materialist astronomy holds that the origin and survival of the solar system can be explained by coincidence. Over the last three centuries, many of its adherents have speculated on how this marvelous order should have come to pass and they have failed to get anywhere. To a materialist, the equilibrium and order of the solar system are inexplicable mysteries.
Astronomers like Kepler and Galileo, among the first to discover this superlative equilibrium, acknowledged it as a deliberate design and a sign of divine intervention in the whole universe. Isaac Newton, recognized as one of the greatest scientific minds of all times, once wrote:
This most elegant system of suns, planets, and comets could arise from the purpose and sovereignty of an intelligent and mighty being…He rules them all, not as a soul but as a sovereign lord of all things, and because of His sovereignty He is commonly called "Lord God Almighty."1
By: http://www.creationofuniverse.com
The solar system is one of the most wonderful examples of this beautiful harmony to be witnessed. There are nine planets with fifty-four known satellites and an unknown number of smaller bodies. The major planets counting outward from the sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Earth is the only one on which life is known to exist. It is surely the only one on which human beings can live and survive unaided thanks to abundant land and water and to a breathable atmosphere.
In the structure of the solar system, we encounter another beautiful example of equilibrium: the balance between a planet's centrifugal force countered by the gravitational attraction of its primary. (In astronomy, a primary is something that another body revolves about. Earth's primary is the sun; the moon's primary is Earth.) Without this balance, everything in the solar system would fly off into the chilling depths of outer space. The balance between these two forces results in paths (orbits) that the planets and other bodies follow around their primaries. If a body moved at too slow a speed, it would plunge into the primary; if it moved at too fast a speed, the primary would be unable to hold onto it, and it would fly off into space. Instead, every body moves at just the right speed to keep it in orbit. Moreover, this equilibrium has to be different for each body because the distance of planets to the sun differs. So do their masses. Therefore, they have to have different orbital speeds not to plunge into the sun or not to fly off into space.
Materialist astronomy holds that the origin and survival of the solar system can be explained by coincidence. Over the last three centuries, many of its adherents have speculated on how this marvelous order should have come to pass and they have failed to get anywhere. To a materialist, the equilibrium and order of the solar system are inexplicable mysteries.
Astronomers like Kepler and Galileo, among the first to discover this superlative equilibrium, acknowledged it as a deliberate design and a sign of divine intervention in the whole universe. Isaac Newton, recognized as one of the greatest scientific minds of all times, once wrote:
This most elegant system of suns, planets, and comets could arise from the purpose and sovereignty of an intelligent and mighty being…He rules them all, not as a soul but as a sovereign lord of all things, and because of His sovereignty He is commonly called "Lord God Almighty."1
| Notes |
 |
| 1. Michael A. Corey, God and the New Cosmology: The Anthropic Design Argument, Maryland: Rowman & Littlefield Publishers, Inc., 1993, p. 259 |
By: http://www.creationofuniverse.com
Saturday, March 21, 2009
Open cluster
An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud, and are still loosely gravitationally bound to each other. In contrast, globular clusters are very tightly bound by gravity. Open clusters have been found only in spiral and irregular galaxies, in which active star formation is occurring. They are usually less than a few hundred million years old: they become disrupted by close encounters with other clusters and clouds of gas as they orbit the galactic center, as well as losing cluster members through internal close encounters.
Young open clusters may still be contained within the molecular cloud from which they formed, illuminating it to create an H II region. Over time, radiation pressure from the cluster will disperse the molecular cloud. Typically, about 10% of the mass of a gas cloud will coalesce into stars before radiation pressure drives the rest away.
Open clusters are very important objects in the study of stellar evolution. Because the stars are all of very similar age and chemical composition, the effects of other more subtle variables on the properties of stars are much more easily studied than they are for isolated stars.
By: id.wikipedia.org
Young open clusters may still be contained within the molecular cloud from which they formed, illuminating it to create an H II region. Over time, radiation pressure from the cluster will disperse the molecular cloud. Typically, about 10% of the mass of a gas cloud will coalesce into stars before radiation pressure drives the rest away.
Open clusters are very important objects in the study of stellar evolution. Because the stars are all of very similar age and chemical composition, the effects of other more subtle variables on the properties of stars are much more easily studied than they are for isolated stars.
By: id.wikipedia.org
Gambar Semu Jupiter
Detil warna semu dari atmosfir Yupiter yang diambil oleh wahana antariksa Voyager 1 menunjukkan Bintik Merah Raksasa dan sebuah pola putih berbentuk oval. Pola berbentuk gelombang di kiri Bintik Merah Raksasa adalah sebuah wilayah dengan gelombang yang kompleks. Untuk memberikan kesan skala Yupiter, badai berbentuk oval putih di bawah Bintik Merah Raksasa memiliki garis tengah yang hampir sama dengan Bumi.
By: id.wikipedia.org
By: id.wikipedia.org
Thursday, March 19, 2009
How to Choose Binoculars For Astronomy
When buying binoculars for astronomy one of the main considerations is the light gathering capability of the binoculars you are looking to buy and therefore the size of the objective lens is extremely important.
Before you start check out the range of binoculars for astronomy that are currently on the market you need to consider the distance you are looking to cover and what level of detail you are hoping to see. If you can imagine that a telescope can provide you with a significantly larger aperature (objective lens) and a wide range of magnification abilities it's understandable that for viewing over longer distances, and to see the finer details, a telescope is often a better option. However that said binoculars can prove useful, even for the serious astronomer, and are an inexpensive way to get started.
The real pro's of using binoculars for astronomy is the minimal set up time, the relatively low cost, portability and the fact that there isn't an endless list of accessories that you need to buy.
Manufacturers generally indicate whether or not their binos are suitable binoculars for astronomy but as a general guide you want to be looking for giant binoculars or binoculars with an objective lens that is 50mm or greater. 10x50's are often a popular choice for astronomy as they are reasonably comfortable to hold yet powerful enough for the basic astronomers needs.
Some manufacturers do make smaller binoculars for astronomy such as the Pentax PCF 8x40 or the higher quality Pentax DCF SP 8x43 and Olympus rate their EXPS I 8x42's as excellent astronomy binoculars. As a general rule, and particularly relating to the smaller binos, if the objective lens is 5 times or more than the magnification you can use them for astronomy.
If you are looking for a real meaty beast then the Celestron Skymaster series ranges from 15 x 70 up to 25 x 100 (which offers the power of a small telescope) and Nikon do the 10 x 70IF SP which is considerably more expensive (around £1200 versus up to £400 for a Skymaster) but you are paying for the quality of the lenses and the superior optical design (one of the leaders in it's class). The bigger you go when you are looking for binoculars for astronomy the greater the power and light gathering abilities so if you opt for a 25 x 100 (25x magnification, 100mm objective lens) you will be able to see further and view objects in greater detail than with a 7 x 35 or a 10 x 50 (for example).
Binoculars for Astronomy, quick check list:
• Fully multi-coated lenses are a must
• Waterproof binoculars are generally best if you want to prevent fogging and view in all weather conditions.
• The best astronomy binoculars come with Bak-4 Porro prisms (Bak-4 glass is high quality glass and porro prisms generally provide greater light transmission and a sharper image than their roof prism counterparts)
• Always check a binoculars suitability for astronomy
• Remember the more powerful the better and if you want a performance similar to a small telescope buy a binocular with the largest possible objective lens.
• For larger binoculars make sure you check tripod / mounting requirements.
• Quality optics is important and no more so than for astronomy. If you can afford high quality binoculars they are well worth paying for.
By: Terry Ross
Before you start check out the range of binoculars for astronomy that are currently on the market you need to consider the distance you are looking to cover and what level of detail you are hoping to see. If you can imagine that a telescope can provide you with a significantly larger aperature (objective lens) and a wide range of magnification abilities it's understandable that for viewing over longer distances, and to see the finer details, a telescope is often a better option. However that said binoculars can prove useful, even for the serious astronomer, and are an inexpensive way to get started.
The real pro's of using binoculars for astronomy is the minimal set up time, the relatively low cost, portability and the fact that there isn't an endless list of accessories that you need to buy.
Manufacturers generally indicate whether or not their binos are suitable binoculars for astronomy but as a general guide you want to be looking for giant binoculars or binoculars with an objective lens that is 50mm or greater. 10x50's are often a popular choice for astronomy as they are reasonably comfortable to hold yet powerful enough for the basic astronomers needs.
Some manufacturers do make smaller binoculars for astronomy such as the Pentax PCF 8x40 or the higher quality Pentax DCF SP 8x43 and Olympus rate their EXPS I 8x42's as excellent astronomy binoculars. As a general rule, and particularly relating to the smaller binos, if the objective lens is 5 times or more than the magnification you can use them for astronomy.
If you are looking for a real meaty beast then the Celestron Skymaster series ranges from 15 x 70 up to 25 x 100 (which offers the power of a small telescope) and Nikon do the 10 x 70IF SP which is considerably more expensive (around £1200 versus up to £400 for a Skymaster) but you are paying for the quality of the lenses and the superior optical design (one of the leaders in it's class). The bigger you go when you are looking for binoculars for astronomy the greater the power and light gathering abilities so if you opt for a 25 x 100 (25x magnification, 100mm objective lens) you will be able to see further and view objects in greater detail than with a 7 x 35 or a 10 x 50 (for example).
Binoculars for Astronomy, quick check list:
• Fully multi-coated lenses are a must
• Waterproof binoculars are generally best if you want to prevent fogging and view in all weather conditions.
• The best astronomy binoculars come with Bak-4 Porro prisms (Bak-4 glass is high quality glass and porro prisms generally provide greater light transmission and a sharper image than their roof prism counterparts)
• Always check a binoculars suitability for astronomy
• Remember the more powerful the better and if you want a performance similar to a small telescope buy a binocular with the largest possible objective lens.
• For larger binoculars make sure you check tripod / mounting requirements.
• Quality optics is important and no more so than for astronomy. If you can afford high quality binoculars they are well worth paying for.
By: Terry Ross
Contributions of Ancient Arabian and Egyptian Scientists on Astronomy
Astronomy (‘Ilm al-Hay’ah) or the science of formation (i.e. of the heavens) deals with such things as the structure of the heavens, the number and configuration of the stars, the signs of the zodiac, the distances of the stars, their size and their motions. It also deals with the compilation of planetary tables, the catalogue of stars for the making of calendars and similar tasks.
The Arabs took a keen interest in the study of heavens. They developed this interest firstly, because they had once worshipped heavenly bodies, (1) and secondly, because the dwellers of the desert who usually traveled at night in connection with trade, war and migration from one place to another, found the direction of their journey with the help of the stars. The clear sky of the desert gave them a chance of making precise observations. Thus there was some locally acquired knowledge of the fixed stars, the movements of the planets and the changes of the weather.
After the advent of Islam, the Muslims had to determine the time of the prayers and the direction of the Ka’bah to turn their faces towards it at the time of prayers. For this purpose it was necessary to know the altitude of the sun and the latitudes and longitudes of all the places where the Muslims lived. The same need arose for the orientation of the mosque. This gave a religious impetus to the study of astronomy and the allied subjects such as astronomical geography and mathematics. On the other hand, the Muslims, who once carried on flourishing trade all over the world and occasionally launched Jihad, had to travel on the land and the sea. As an aid to travel, navigation and meteorology, a by product of navigation, they needed star maps. The necessity of such maps was also a cause of their interest in astronomy.
There was a group of astronomers who believed in the influence of heavenly bodies on the terrestrial affairs, and the fate and future of human beings. According to them, the prognostication of sub-lunar events from the revolution of the heavens, the signs of the zodiac in the ascendant and the motion of the planets was possible. The science dealing with such influences was termed as Astrology (’Ilm-Ahkam al-Nujum). Astrology, as a part of astronomy, was studied and developed by ancient Babylonians. The study of this art or science was then made in Greece and Rome, a few centuries before the opening of the Christian era. It was also cultivated in India, China and Egypt. From the 7th to the 13th century it was further developed by the Muslims and later on by the Europeans. In the 14th and the 15th centuries, the astrologers had great influence on the kings of the European countries. (2) The orthodox Muslims did not believe in the influence of the heavenly bodies on fate or the future of human beings.
The regular study of astronomy and mathematics was begun at Baghdad in the second half of the 8th century during the reign of the second ‘Abbasi Caliph Al-Mansür. After that the patronage and generosity of other Muslim rulers, particularly of the seventh ‘Abbasi Caliph Al-Ma’mun, provided stimulation to the astronomical and mathematical researches of every kind. Indian, Persian and Greek astronomical works were translated into Arabic, and for making the astronomical observations the observatories were established by the caliphs and private persons at various places in the Muslim world. Astronomy was studied with great interest with the result that the number of Muslim astronomers raised surprisingly in a short period of time, and by the end of the 10th century, a large number of eminent Muslim astronomers gathered in Baghdad. In the 11th and the 12th centuries astronomy flourished in Muslim Spain where a good deal of creative and original work on this branch of science was done.
The Muslim scientists attached utmost importance to accuracy in observations and calculations, without caring for the length of time needed for it. Thus sometimes their astronomical researches extended for more than forty years. Due to this desire of accuracy the Muslims did not accept as such the astronomical tables or measurements of Ptolemy, a great Greek astronomer and mathematician. They only accepted his planetary theory just to provide a basis for astronomical research. They themselves conducted astronomical researches in Baghdad, Samarqand, Nishapur, Cordova, Damascus and Ray, and after making a careful study of the heavens they not only corrected and amplified Ptolemy’s astronomical tables, but also compiled a number of new ones and drew up new star catalogues. On the basis of fresh observations, the Ptolemaic system was repeatedly criticized by the Muslim astronomers, particularly those of Spain.
The investigations on astronomy were continued, and till the end of the 11th century, nearly all the original and creative work was done by Muslims, and even the works of non-Muslims were written in Arabic. Astronomy reached its highest in the 13th and 14th centuries. In the 12th century, the Christians and Jews started the work of translation from Arabic into Latin and Hebrew, and began to conduct research in this field. But until the end of the 13th century, no mathematical and astronomical work comparable to that of the Muslims could be produced by the Christians or Jews. It is interesting to note that in the 12th century, while Ptolemy’s astronomical work, Almagest, after a thorough study and research, was subjected to severe criticism by Muslims particularly those of Spain, the study of this work was begun in the Latin world.
Besides compiling the astronomical tables, the Muslims prepared celestial globes on which the positions and magnitudes of the stars were represented. The globe is of Greek origin, but since Ptolemy’s time there has been a continuous improvement on it. The Muslim scientists also wrote comprehensive books on astronomy and mathematics, and also composed treatises on various branches of this science.
The Muslim astronomers also prepared the star maps to preserve the old astronomical knowledge, and to use them as an aid to travel, navigation and meteorology.
A great incentive for the study of astronomy came from an Indian astronomical work called Siddhanta which was brought to the court of Baghdad by a Hindu named Kanka. Kanka met Ya’qüb Ibn Tãriq in 767 who was one of the greatest astronomers of his time. Ya’qüb Ibn Tãriq introduced him to the Caliph Al-Mansür.(3) Kanka showed the book to the Caliph who ordered Muhammad Ibn Ibrahim Al-Fazãri to translate it into Arabic.(4) He also ordered that a work based on Siddhanta should be composed, which could serve as a reference book for the Arabs. Muhammad Ibn Ibrahim took this responsibility and prepared a book which was called by the astronomers as Sind Hind al-Kabir (the great Siddhanta). (5) It was used until the time of the Caliph Al-Ma’mun. Then Al-Khwãrizmi, who was one of the greatest scientists, prepared a summary of this book. He also compiled astronomical and trigonometrical tables according to the combined methods of Indians, Persians and Greeks. These tables were revised by Maslamah al-Majriti (c. the second half of the 10th century). They gained so much popularity that they were used even in China. In the 12th century, the translation of these tables was made into Latin. (5) Al-Khawarizmi glimpsed in his works on astral motion and the force of attraction the law of universal gravitation.
The astronomer Ibrahim Ibn Habib al-Fazãri was the first Muslim who constructed astrolabes. He composed a poem on astrology, and compiled a Zij (calendar) according to the Arab method. He also wrote on the use of astrolabes and on the armillary spheres. (6)
In 762-63 the Persian astronomer and engineer, Naubakht, together with Masha’ Allah (Latin Macellama, Macelarama, Messahala), made a survey before the building of Baghdad. Masha’ Allah (d. 815 or 820) was one of the earliest astronomers and astrologers, who flourished under the Caliph Al-Mansür. (7) Naubakht (d. 776-77) was the author of a book on astrological judgments entitled Kitäb al-Ahkam. (8)
During the reign of the Caliph al-Ma’mun, the important work of translation of Ptolemy’s Almagest from Greek into Arabic was completed. The Caliph was very anxious to get it translated correctly. It was translated several timed. Many commentaries on it were written. Its summaries were also made. The Minister Yahya Ibn Khalid Barmaki was the first to get it translated. A group of scholars wrote for him a commentary on this book, but he did not like it. He appointed Abu Hasan and Salman who were attached to the scientific academy called Bait al-Hikmah (The house of wisdom) to write a commentary on it.(9) The Almagest represents the best example of Greek classical works on astronomy. It served as a basis for the later astronomical works. Al-Hajjaj Ibn-Yusuf was one of the first translators of the Almagest. He made this translation on the basis of a Syriac version. (10)
The Caliph al-Ma’mun (169-218 / 786-833) was very fond of philosophy and science. The more he got acquainted with the interesting problems of science, the more his interest grew in the practical work. He built an observatory at Baghdad in his Bait al-Hikmah and another in the plain of Tadmor (Palmyra). In these observatories the fundamental elements of the Almagest like the inclination of the ecliptic, the length of the solar year, and the precession of the equinoxes were verified. Observations on the celestial motions were carried out and geodetic measurements were made. (11)
Al-Ma’mun ordered Ahmed, Muhammad and Hasan, who were eminent scientists and his courtiers, to measure in collaboration with other court scientists the length of the terrestrial degree and the circumference’ of the earth in some vast planes. The planes of Sinjar and Tadmor were selected for this purpose. The astronomers stayed at a place and noted with the help of instruments the altitude of the North. Pole, and pitched a nail there. Then tying a long rope with the nail, they carried the rope in the direction of the North. Where the rope ended they pitched another nail and tied another rope with it, and proceeded in the same direction. They continued this process as well as observations on the altitude of the North Pole, until on reaching a particular spot they noticed that the altitude of this Pole had increased by one degree. The distance they covered was also measured, which was found to be 56 2/3 miles. From, these observations it was inferred that for each terrestrial degree the distance covered on the earth amounts to 56 2/3 miles. The same operation was repeated in the direction of the South where at one spot they noticed that the altitude had decreased by, one degree. The distance covered was the same as in the first case. Now on multiplying this distance by 360 which is the total number of terrestrial degrees, the circumference of the earth was found to be equal to 20,400 miles, and the diameter equal to 6,500 miles. (12)
The chief of astronomers who carried observations under al-Ma’mun was Sanad Ibn ‘Ali. He was a Jewish convert to Islam. He constructed an observatory (Kanisah) at the back of the Shamãsiah Gate at the palace of Mu’izz al-Dawlah in Baghdad. An astronomical table and some writings on astronomy and mathematics, including a book on Arabic numerals, are ascribed to him. (13)
‘Ali Ibn ‘Isa al-Astur1ãbi who flourished in Baghdad and Damascus in the first half of the 9th century, took part in the measurement of the length of the terrestrial degree ordered by al-Ma’mun. He made astronomical observations at Baghdad and Damascus from 829 to 833. He was the famous constructor of astrolabes; hence the nickname al-Asturlãbi (maker of astrolabe). He wrote a treatise on astrolabes, which is one of the earliest works on this instrument. (14)
Yahya Ibn Abi Mansür also took part in the observations made at Baghdad in 829-30, and compiled the astronomical tables called Ma’munic tables. Like the tables of Habash these, too, are a collective work of ‘various astronomers. Al-Marwarudhi, who also flourished under al-Ma’mun, made solar observations. (15)
In the 9th century astronomy flourished in the East, Astronomical researches were conducted in the observatories of Baghdad, Damascus and other places. More original and improved work was done in the second half of the 10th century. The elaboration of trigonometry, which was considered to be a branch of astronomy at that time, was also continued. A great attention was paid to the construction of good astronomical instruments, especially to the spherical astrolabe which was newly introduced at that time. Hamid Ibn ‘Ali was a famous constructor of spherical astrolabes. Jãbir Ibn Sinan was also a maker of this as well as of other astronomical instruments. According to al-Biruni, he was the first to make a spherical astrolabe. Al-Nairizi wrote on this instrument an elaborate treatise which represents the best Arabic work on this topic. In this treatise the author, after giving the introduction, describes the instruments, and gives its applications. Beside this work, al-Nairizi compiled astronomical tables. A great scientist al-Mähani made for 33 years (833—886), a series of observations on lunar and solar eclipses and planetary conjunctions. Another astronomer of this time Ahmad al- Nahâwandi, who flourished at the time of Yahya Ibn Khalid Ibn Barmak, made astronomical observations at Jundishapur and compiled tables called Mushtamil. (16)
After carrying out astronomical observations for ten years (825 to 835) Habash al-Hãsib compiled three astronomical tables. The first were according to the Hindu method (based on Siddhanta). The second called Al-Zij al-Mumtahan (the “tested Tables”) were according to the Arab method. They were very important and were probably due to the co-operative efforts of al-Ma’mun’s astronomers. The third called Al-Zij Al-Saghir (the small tables) was commonly known as the Tables of Shah. Habash al-Hãsib determined the time of the solar eclipse of the year 829. He was the first to determine time by an altitude (in this case, of the sun). This method was generally accepted and adopted by Muslim astronomers. (17)
The most illustrious scholar of this age, and one of the greatest astronomers of Islam, was ‘Abd Allah Muhammad Ibn Jãbir Ibn Sinan al-Battãni (Latin; Albategnius, Albatenius). His ancestors were Sabeans of Harran, but he himself was a Muslim. He carried out astronomical observations of a wide range and with remarkable accuracy for about 41 years (877—918). He determined many astronomical co-efficients, like the precession 54.5” a year, inclination of the ecliptic 23° 35’, with great accuracy. He noticed an increase of 16° 47’ in the longitude of the sun’s apogee since Ptolemy’s time. This led to the discovery of the motion of the solar apsides and of slow variation in the equation of time. Al-Battãni proved the possibility of the annular eclipses of the sun. He also wrote many astrological works. His main work is a large astronomical treatise including the astronomical tables. His tables contain a catalogue of fixed stars for the year 880—81. His work is an advance on that of al-Khwãrizmi, and shows more divergence from Indian methods. Observations regarding the first appearance of the new moon, the length of the tropic and sidereal year, the obliquity of the ecliptic, the lunar anomalies, the parallaxes, etc., are more complicated and more accurately made by al-Battãni than by al-Khwãrizmi
Al-Battãni’s astronomical treatise was translated into Latin and Spanish in the 12th and 13th centuries respectively. It exerted a great influence on the European scholars of the middle Ages and Renaissance. (l8)
Thãbit Ibn Qurrah (d. 901) who was a physician, mathematician, astronomer and translator from Greek and Syriac into Arabic published his solar observations made at Baghdad. He particularly determined the altitude of the sun and the length of the solar year. (19)
The astronomer and mathematician Wijan Ibn Rustam al-Kühi wrote many astronomical and mathematical works, including a treatise on the construction of the astrolabe. He was the head of the astronomers working in 988 at the Buwayhid Sharaf al-Dawlah’s observatory. (20) His co-worker Ahmad Ibn Muhammad al-Saghâni was the inventor and maker of astronomical instruments. Abu’l-Wafã is said to be the discoverer of the variation, the third inequality of the moon; a discovery which was later ascribed to Tycho Brahe. (21)
‘Ali Ibn al-Husain al-’Alawi (d. 985) showed a remarkable accuracy in observations. He compiled astronomical tables which remained very popular for at least two centuries. (22)
Now we come to a famous astronomer of the 10th century, named Abu’l-Husain ‘Abd al-Rahman al-Sufi. He was born in Ray (Persia) in 903, and died in 966. He was a prominent astronomer of the medieval times. His knowledge of both the Islamic and Greek astronomy, particularly uranometry, was comprehensive. He was the first to observe the change of the colour of stars, the change in the magnitude of stars, the proper motion of stars, the long period variable stars and the Southern constellations which have been wrongly ascribed by modern astronomers to some later ones.
Abd al-Rahman al-Sufi was patronized by the Buwayhid ruler Adud al-Dawlah (949—982) who was a great patron of astronomy, and had built an observatory at Shiraz. Al-Sufi wrote for the ruler a book on uranometry, entitled Suwar al-Kawàkib (The book of the fixed stars). In this book he gives a complete description of the constellations of the heavens. He also gives the position of each star of the constellations, illustrating with pictures. The book contains 55 astronomical tables along with illustrations of 48 constellations in 96 diagrams as seen in the heavens. The artistic value of the pictorial illustrations in the Mss. of this work is very great, and represents one of the best examples of the Persian miniature paintings. Al-Sufi has not only corrected the errors of observations in the work of his predecessors like al-Battãni, but also, pointed out many faulty observations found in Ptolemy’s Almagest. He defined carefully the boundaries of each constellation, and recorded the magnitudes and positions of stars after making new observations.
The Suwar al-Kawàkib is one of the three masterpieces of observational astronomy of the medieval times; the other two being the catalogues of Ibn Yünus and Ulugh Beg prepared in the 12th and 15th centuries respectively. It is an addition to the Muslims’ knowledge on uranometry. The later astronomers, like al-Biruni, Alfonso, Prince of Castile, Khwãjah Näsir al-Din Tusi, Prince Ulugh Beg and Jai Singh II, based their catalogues of stars on this authentic catalogue. This work was translated into Latin, French and Persian, and a commentary on it was written in Spanish.
It served as a basis for later works in Western Europe. The modern astronomers like Hauber, Down, Argelander, Ideler, Schellerup and Knobel had made an extensive use of it.
Al-Sufi prepared a fine celestial globe. Several celestial globes which cover the period from the 11th to the 18th century show the star positions and magnitudes according to al-Sufi. He showed a remarkable accuracy in the design of the astrolabes. He wrote a treatise on this instrument. In this treatise he throws light on the astronomical techniques as practiced it that time. (23)
Another great astronomer and one of the greatest Muslim astronomers was Abu’l-Hasan Ali Ibn Abi Said ‘Abd al-Rahman Ibn Ahmad Ibn Yünus al-Sadafi, generally known as Ibn Yünus. He was well versed in Arabic literature, poetry and history, and had knowledge of many other subjects. He belonged to Egypt where he died in 1009. He was a courtier of the Fatimi Caliph al-‘Aziz Billah (975—996). He got a chance of working in a well-equipped observatory which was the part of a Muslim academy of science, named Dar al-Hikmah (the house of wisdom) founded in Cairo by the Fatimi rulers. He made astronomical observations, and by the order of the Caliph al-‘Aziz he compiled the astronomical tables. The work of compilation of these tables was begun in 990 during the lifetime of the Caliph, but it was completed after his death under his son al- Hakim (966—1020). Hence they were named after him Al-Zij al-Kabir al-Hakimi. In these tables he entered his observations about the eclipses and conjunctions, old and new, improved values of astronomical constants (inclination of the ecliptic, 23° 35’; longitude of the sun’s apogee, 86° 10’; solar parallax reduced from 3’ to 2’; precession, 51.2” a year). He gave an account of the geodetic measurements which were carried on by the order of the Caliph al-Ma’mun in the ninth century.
Ibn Yünus in his astronomical tables (written in 4 volumes) corrected the errors of observations in the astronomical tables of his predecessors. The people of Egypt relied on these tables. It is said that after their compilation the use of all the previous tables in the world was given up. Even the astronomers of China greatly utilized them. The translation of a large part of the tables, except the chronological section, has been made in French in 1804.
Beside these-tables, Ibn Yünus has composed many books. One of these is Jadawil al-Samt (the tables of direction), and the other is the Jadawil al-Shams wa’l-Qamar (the tables of the sun and the moon). (24)
A famous astronomer of the 11th century, who belonged to Cordova (Spain), was Abu Ishaq Ibrahim Ibn Yahya al-Naqqàsh, commonly known as Ibn al-Zarqàli or al-Zarqàli (Latin: Arzachel). He was also an eminent astronomer of this century. He lived from 1029 to 1087. He was the best observer of his time, who made astronomical observations for about 19 years (1061—1080). He invented an improved astrolabe called Safihah (Saphaea Arzachelis) on which he also wrote a treatise. It was translated into Latin, Hebrew and many vernaculars. Al-Zarqàli was the first to prove explicitly the motion of the solar apogee with reference to the stars. According to his calculations it was equal to 12.04” per year (the real value being 11.8”). He edited the planetary tables called Toledan Tables. These tables were probably the result of the observations made in Toledo by him and by a great observer Ibn Said in collaboration with other Muslim and Jewish astronomers. They were translated into Latin and enjoyed much fame. (25)
A famous astronomer, mathematician and poet, ‘Umar Ibn al-Khayyãm, reformed the old Persian calendar which had been replaced by the Islamic calendar after the Muslim conquest of Persia. This reformed calendar was called Al-Tàrikh al-Jalãli after the name of the Saljuq Sultan Malik Shah Jalal al-Din who in 1074-75 called ‘Umar Ibn al-Khayyãm to his observatory for making this reform. Many interpretations have been given to it. Each interpretation is accurate to a certain degree, but at any rate ‘Umar’s calendar was probably more accurate than the Gregorian (Christian) calendar. Three interpretations, the second of which seems to be the most accurate, are being quoted here along with the authority giving the interpretation and the resulting error.
1. Al-Shirãzi’s interpretation: 17 intercalary days in 70 years;’ error. 1 day in about 1540 years.
2. Ulugh Beg’s interpretation: 15 intercalary days in 62 years; error, 1 day in about 3770 years.
3. Modern interpretation: 8 intercalary days in 33 years: error, 1 day in about 5,000
(in the Gregorian calendar there is an error of 1 day in 3330 years). (26)
The greatest astronomer of the 12th century, who also belonged to Spain, was Abu Muhammad Jãbir Ibn Aflah. He was born or lived in Seville. He vigorously criticized the Ptolemaic theory of planets, and wrote a book on astronomy entitled Islah al-Majisti (the correction of the Almagest). He was of the view that the lower planets Mercury and Venus), at least, must have visible parallaxes. Venus may happen to be exactly on the line joining the sun and the earth. The most important part of his book is the introduction on trigonometry. The book was soon translated into Latin and Hebrew. Jãbir Ibn Aflah is said to be the inventor of the astronomical instrument called turquet (torquetum) which contains two graduated circles in two perpendicular planes. The same invention has also been ascribed to two other persons, namely, Frances of Leige (11th century) and Näsir al-Din Tusi (13th century). The turquet was introduced into the Latin West by Regionomentus. It gained a great popularity in the 15th and 17th centuries. (27)
Another astronomer of the time was Abu’l Qãsim Hibat Allah Ibn Husain al-Badi’ al-Asturlãbi. He was also a physician, mathematician, poet and litterateur. He was the greatest expert of his time in the knowledge and construction of astrolabes; hence his nickname al-Asturlãbi. In 1120—30 astronomical observations were made under his direction, and astronomical tables were compiled. The observations were carried out in the palace of the Saljuq Sultan of Iran, Mughith al-Din Mahmud (1117—1131). The tables were dedicated to the Sultan, and were called after him the Mahmudic tables. Al-Asturlãbi was very much praised by Muslim biographers. He died in Baghdad in 1139-40. (28)
In the 13th century there flourished in the East a great scholar of Persian origin, named Abu Ja’far Muhammad Ibn Muhammad Ibn al-Hasan, Näsir al-Din al-Tusi al-Muhaqqiq, (the researcher). He was born in Tus (Khurasan) in 1201, and died in Baghdad in 1274. He was a philosopher, mathematician, astronomer and physician. He was one of the greatest Muslim mathematicians and scientists. He wrote both in Arabic and Persian. It is said that he knew Greek as well. He joined the Mongol service, and was later made administrator of the Waqf revenues.
While he was administrator he resided at Maragha in Asia Minor (1259—1274). Here he made astronomical observations in an observatory established by the Mongol ruler Hulagu Khan II after he had defeated the last ‘Abbasi Caliph, al-Mu’tasim, in 1258. A library was attached to it. It is said to have contained 4, 00,000 volumes which the Mongol armies had collected in Syria, Mesopotamia and Persia. Näsir al-Din was the first director of this observatory. He was succeeded by two of his sons.
Näsir al-Din was well acquainted with the knowledge of the Greeks. He wrote about 64 works on many subjects. Here we shall, consider only some of his astronomical and astrological works. The most important astronomical work of Näsir al-Din is the Tadhkirah fi ‘Ilm al-Hay’ah (The description of astronomy) which is a condensed summary of astronomy. To explain it many commentaries and super commentaries have been written. The work enjoyed much popularity, it consists of four chapters. The second chapter, beside other things, contains interesting criticism of the Ptolemy’s Almagest in which he showed a great ingenuity. The criticism chiefly concerns the anomalies of the moon, and the motion in the latitude of the planets (particularly Mercury and Venus) ; also the proposition of a new system to replace the complicated Ptolemaic machinery of deferents and epicycles. His new and forceful criticism of astronomy as well as of other Muslim astronomers helped Copernicus in making his reform’. Näsir al-Din wrote one treatise on the five quadrants and two treatises on astrolabe. He also wrote two treatises on calendar.
Näsir al-Din made observations in the observatory at Maragha which was well equipped with good astronomical instruments. He prepared new astronomical tables called after the Mongol ruler, Al-Zij al-Ilkhäni. Nasir al-Din asked the ruler to give him a period of 30 years to compile the tables, because it was the shortest period during which the planetary cycles were completed. But the ruler refused, and gave him only 12 years to accomplish this task. Nasir al-Din tried a succeeded in completing the tables within this time. They were based upon new observations. But the use of the earlier ones had also been made.
The Zij-i- Ilkhäni was originally written in Persian. It consists of four books dealing respectively with (a) Chinese, Greek, Arabic and Persian Chronology; (b) motions of the planets; (c) ephemeredes and (d) astrological operations. The translation of the Zij was made into Arabic, and commentaries on it were written. Finally, a sort of supplement to it was compiled by Jamshed Ibn Mas’üd al-Käshi (d. 840/1436), the first director of Ulugh Beg’s observatory in Samarqand. These tables enjoyed a great popularity in the East including China, and were, continued to be used even after the compilation of new tables by Ulugh Beg in 1437. (29)
A contemporary of Nasir al-Din, Mu’ayyid al-Din al-Urdi al-Dimashqi also took part with him in compiling the tables. He was a Syrian astronomer, architect and engineer. He started his career as a technician in Syria. He did some hydraulic work in Damascus, and also constructed there an astronomical instrument for al-Mansür Ibrahim (King of Hims, 1239—1245). In about 1259 he went to Maragha, and helped Nasir al-Din in organizing the observatory and compiling the tables. It seems that the instruments, remarkably precise, were constructed under his supervision in the foundry attached to the observatory.
Al-Urdi was the author of a treatise in which he also described the instruments used in the observatory of Maragha, and explained their use and construction. The instruments are as follows:—
(1) mural quadrant (2) armillary sphere (3) solstitial armil (4) equinoctial armil (5) Hipparch’s diopter (alidade); (6) instrument with two quadrants (7) instrument with two limbs (8) instruments to determine sines and azimuths (9) instruments to determine sines and versed sines, (10) the perfect instrument (a universal instrument) (11) parallactic ruler (after Ptolemy).
Al-Urdi was also the author of two other treatises; one on the construction of a perfect sphere and another on the determination of the distance between the centre of the sun and the apogee. He compiled astronomical tables, and wrote on Ptolemaic astronomy.
In 1279 or 1289 al-Urdi’s son Muhammad made a celestial globe. It consisted of two brass hemispheres separated by the ecliptic. Its diameter was 140 mm. It had a horizon circle. Two movable half circles were attached to the zenith point by a pivot. These circles are graduated and are used to determine the declination and right ascension of any star. Forty-eight constellations, the equator and the ecliptic are inlaid with silver or gold. It is preserved in the mathematical salon of Dresden. (30)
The works of Muslim astronomers were later translated into Latin, Hebrew and vernaculars by the Christian and Jewish scholars, some of the technical terms including azimuth (al-Samt), Algol (Alfol), Achernar (Akhir al-Nahr), passed into the European languages. The names of many stars such as akrab (Aqrab), Algedi (al-Jadi, the kid), Altair (al-ta’ir ,the player), Denab (dhanb, tail), Pherkad (Farqad, calf), Adara (‘Adhrah) Aldebaran (al-dibràn), which are of Arabic origin, also passed into these languages. The stars being countless in number, their separate study is not possible. They were, therefore, divided into various groups, and the groups were named after the things and animals with which they resembled.
REFERENCES :-
1. Briffault, Robert , The Making of’ Humanity, Lahore, 1980, p. 187.
2. Encyclopedia Britannica, London, Vol. II, p.575.
3. Abu’l Hasan Ali Ibn Yusuf , Al-Qifti , Tàrikh al-Hikmah,’ Leipzig, 1903, p. 265.
Sarton, George, Introduction to the History of Science, Washington 1927, vol. I. p. 530.
4. Ibid.
5. Ibid, p. 563.
6. Al-Qifti, op. cit., 57.
7. Ibid., p. 327.
Sarton, op. cit. p. 531.
8. Ibid.
9. Ibid. p. 557.
Haji Khalifah, Kashf al-Zunün, Istanbul, 1943, vol. II, p. 1594.
10. Sarton, op. cit., p. 562.
11. Ibid, p. 558.
12. Shibli Nu’mani, Al-Ma’mun, Agra, 1894, pp. 49— 50,
13. Ibn Nadeem, Al-Fehrist, Matba’ah al-Rahmaniyah, Cairo, n.d.. p. 383.
14. Shibli Nu’mani, op. cit. pp. 49—50
Sarton, op. cit. p. 566.
15. Ibid.
16. Sarton, op. cit.. p. 585.
17. Al-Qifti, op. cit. p. 170.
18. Ibid, p. 280.
Sarton, op. cit. p. 5858.
19. Ibid., p. 599.
20. Al-Qifti, op. cit. p. 351.
21. Sarton, op. cit. p. 666.
22. Ibid.
23. A1-Süfi, ‘Abd al-Rahman, Swar al-Kawàkib, Hyderabad, preface by M. Nizamuddin, and J.J. Winter, pp. 1-7.
24. Al-Qifti, op. cit., p. 226.
25. A1-Qifti, op. cit., p. 230.
26. Sarton, op. cit., p. 758,
27 Ibid., p.759
28. Ibid, vol. II, part I, p. 206.
29. Ibid., part I, p. 204.
30. Al-Baghdadi, Isma’il Bãshã, Hadiyyat al-‘Arifin, Istanbul, 1951, vol. II, p. 131.
31. Sarton, op. cit. vol. II, part II, p. 1005.
32. Ibid., pp. 1013-1014.
By: Md. Wasim Aktar
Deptt. of Agril. Chemicals, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India.
The Arabs took a keen interest in the study of heavens. They developed this interest firstly, because they had once worshipped heavenly bodies, (1) and secondly, because the dwellers of the desert who usually traveled at night in connection with trade, war and migration from one place to another, found the direction of their journey with the help of the stars. The clear sky of the desert gave them a chance of making precise observations. Thus there was some locally acquired knowledge of the fixed stars, the movements of the planets and the changes of the weather.
After the advent of Islam, the Muslims had to determine the time of the prayers and the direction of the Ka’bah to turn their faces towards it at the time of prayers. For this purpose it was necessary to know the altitude of the sun and the latitudes and longitudes of all the places where the Muslims lived. The same need arose for the orientation of the mosque. This gave a religious impetus to the study of astronomy and the allied subjects such as astronomical geography and mathematics. On the other hand, the Muslims, who once carried on flourishing trade all over the world and occasionally launched Jihad, had to travel on the land and the sea. As an aid to travel, navigation and meteorology, a by product of navigation, they needed star maps. The necessity of such maps was also a cause of their interest in astronomy.
There was a group of astronomers who believed in the influence of heavenly bodies on the terrestrial affairs, and the fate and future of human beings. According to them, the prognostication of sub-lunar events from the revolution of the heavens, the signs of the zodiac in the ascendant and the motion of the planets was possible. The science dealing with such influences was termed as Astrology (’Ilm-Ahkam al-Nujum). Astrology, as a part of astronomy, was studied and developed by ancient Babylonians. The study of this art or science was then made in Greece and Rome, a few centuries before the opening of the Christian era. It was also cultivated in India, China and Egypt. From the 7th to the 13th century it was further developed by the Muslims and later on by the Europeans. In the 14th and the 15th centuries, the astrologers had great influence on the kings of the European countries. (2) The orthodox Muslims did not believe in the influence of the heavenly bodies on fate or the future of human beings.
The regular study of astronomy and mathematics was begun at Baghdad in the second half of the 8th century during the reign of the second ‘Abbasi Caliph Al-Mansür. After that the patronage and generosity of other Muslim rulers, particularly of the seventh ‘Abbasi Caliph Al-Ma’mun, provided stimulation to the astronomical and mathematical researches of every kind. Indian, Persian and Greek astronomical works were translated into Arabic, and for making the astronomical observations the observatories were established by the caliphs and private persons at various places in the Muslim world. Astronomy was studied with great interest with the result that the number of Muslim astronomers raised surprisingly in a short period of time, and by the end of the 10th century, a large number of eminent Muslim astronomers gathered in Baghdad. In the 11th and the 12th centuries astronomy flourished in Muslim Spain where a good deal of creative and original work on this branch of science was done.
The Muslim scientists attached utmost importance to accuracy in observations and calculations, without caring for the length of time needed for it. Thus sometimes their astronomical researches extended for more than forty years. Due to this desire of accuracy the Muslims did not accept as such the astronomical tables or measurements of Ptolemy, a great Greek astronomer and mathematician. They only accepted his planetary theory just to provide a basis for astronomical research. They themselves conducted astronomical researches in Baghdad, Samarqand, Nishapur, Cordova, Damascus and Ray, and after making a careful study of the heavens they not only corrected and amplified Ptolemy’s astronomical tables, but also compiled a number of new ones and drew up new star catalogues. On the basis of fresh observations, the Ptolemaic system was repeatedly criticized by the Muslim astronomers, particularly those of Spain.
The investigations on astronomy were continued, and till the end of the 11th century, nearly all the original and creative work was done by Muslims, and even the works of non-Muslims were written in Arabic. Astronomy reached its highest in the 13th and 14th centuries. In the 12th century, the Christians and Jews started the work of translation from Arabic into Latin and Hebrew, and began to conduct research in this field. But until the end of the 13th century, no mathematical and astronomical work comparable to that of the Muslims could be produced by the Christians or Jews. It is interesting to note that in the 12th century, while Ptolemy’s astronomical work, Almagest, after a thorough study and research, was subjected to severe criticism by Muslims particularly those of Spain, the study of this work was begun in the Latin world.
Besides compiling the astronomical tables, the Muslims prepared celestial globes on which the positions and magnitudes of the stars were represented. The globe is of Greek origin, but since Ptolemy’s time there has been a continuous improvement on it. The Muslim scientists also wrote comprehensive books on astronomy and mathematics, and also composed treatises on various branches of this science.
The Muslim astronomers also prepared the star maps to preserve the old astronomical knowledge, and to use them as an aid to travel, navigation and meteorology.
A great incentive for the study of astronomy came from an Indian astronomical work called Siddhanta which was brought to the court of Baghdad by a Hindu named Kanka. Kanka met Ya’qüb Ibn Tãriq in 767 who was one of the greatest astronomers of his time. Ya’qüb Ibn Tãriq introduced him to the Caliph Al-Mansür.(3) Kanka showed the book to the Caliph who ordered Muhammad Ibn Ibrahim Al-Fazãri to translate it into Arabic.(4) He also ordered that a work based on Siddhanta should be composed, which could serve as a reference book for the Arabs. Muhammad Ibn Ibrahim took this responsibility and prepared a book which was called by the astronomers as Sind Hind al-Kabir (the great Siddhanta). (5) It was used until the time of the Caliph Al-Ma’mun. Then Al-Khwãrizmi, who was one of the greatest scientists, prepared a summary of this book. He also compiled astronomical and trigonometrical tables according to the combined methods of Indians, Persians and Greeks. These tables were revised by Maslamah al-Majriti (c. the second half of the 10th century). They gained so much popularity that they were used even in China. In the 12th century, the translation of these tables was made into Latin. (5) Al-Khawarizmi glimpsed in his works on astral motion and the force of attraction the law of universal gravitation.
The astronomer Ibrahim Ibn Habib al-Fazãri was the first Muslim who constructed astrolabes. He composed a poem on astrology, and compiled a Zij (calendar) according to the Arab method. He also wrote on the use of astrolabes and on the armillary spheres. (6)
In 762-63 the Persian astronomer and engineer, Naubakht, together with Masha’ Allah (Latin Macellama, Macelarama, Messahala), made a survey before the building of Baghdad. Masha’ Allah (d. 815 or 820) was one of the earliest astronomers and astrologers, who flourished under the Caliph Al-Mansür. (7) Naubakht (d. 776-77) was the author of a book on astrological judgments entitled Kitäb al-Ahkam. (8)
During the reign of the Caliph al-Ma’mun, the important work of translation of Ptolemy’s Almagest from Greek into Arabic was completed. The Caliph was very anxious to get it translated correctly. It was translated several timed. Many commentaries on it were written. Its summaries were also made. The Minister Yahya Ibn Khalid Barmaki was the first to get it translated. A group of scholars wrote for him a commentary on this book, but he did not like it. He appointed Abu Hasan and Salman who were attached to the scientific academy called Bait al-Hikmah (The house of wisdom) to write a commentary on it.(9) The Almagest represents the best example of Greek classical works on astronomy. It served as a basis for the later astronomical works. Al-Hajjaj Ibn-Yusuf was one of the first translators of the Almagest. He made this translation on the basis of a Syriac version. (10)
The Caliph al-Ma’mun (169-218 / 786-833) was very fond of philosophy and science. The more he got acquainted with the interesting problems of science, the more his interest grew in the practical work. He built an observatory at Baghdad in his Bait al-Hikmah and another in the plain of Tadmor (Palmyra). In these observatories the fundamental elements of the Almagest like the inclination of the ecliptic, the length of the solar year, and the precession of the equinoxes were verified. Observations on the celestial motions were carried out and geodetic measurements were made. (11)
Al-Ma’mun ordered Ahmed, Muhammad and Hasan, who were eminent scientists and his courtiers, to measure in collaboration with other court scientists the length of the terrestrial degree and the circumference’ of the earth in some vast planes. The planes of Sinjar and Tadmor were selected for this purpose. The astronomers stayed at a place and noted with the help of instruments the altitude of the North. Pole, and pitched a nail there. Then tying a long rope with the nail, they carried the rope in the direction of the North. Where the rope ended they pitched another nail and tied another rope with it, and proceeded in the same direction. They continued this process as well as observations on the altitude of the North Pole, until on reaching a particular spot they noticed that the altitude of this Pole had increased by one degree. The distance they covered was also measured, which was found to be 56 2/3 miles. From, these observations it was inferred that for each terrestrial degree the distance covered on the earth amounts to 56 2/3 miles. The same operation was repeated in the direction of the South where at one spot they noticed that the altitude had decreased by, one degree. The distance covered was the same as in the first case. Now on multiplying this distance by 360 which is the total number of terrestrial degrees, the circumference of the earth was found to be equal to 20,400 miles, and the diameter equal to 6,500 miles. (12)
The chief of astronomers who carried observations under al-Ma’mun was Sanad Ibn ‘Ali. He was a Jewish convert to Islam. He constructed an observatory (Kanisah) at the back of the Shamãsiah Gate at the palace of Mu’izz al-Dawlah in Baghdad. An astronomical table and some writings on astronomy and mathematics, including a book on Arabic numerals, are ascribed to him. (13)
‘Ali Ibn ‘Isa al-Astur1ãbi who flourished in Baghdad and Damascus in the first half of the 9th century, took part in the measurement of the length of the terrestrial degree ordered by al-Ma’mun. He made astronomical observations at Baghdad and Damascus from 829 to 833. He was the famous constructor of astrolabes; hence the nickname al-Asturlãbi (maker of astrolabe). He wrote a treatise on astrolabes, which is one of the earliest works on this instrument. (14)
Yahya Ibn Abi Mansür also took part in the observations made at Baghdad in 829-30, and compiled the astronomical tables called Ma’munic tables. Like the tables of Habash these, too, are a collective work of ‘various astronomers. Al-Marwarudhi, who also flourished under al-Ma’mun, made solar observations. (15)
In the 9th century astronomy flourished in the East, Astronomical researches were conducted in the observatories of Baghdad, Damascus and other places. More original and improved work was done in the second half of the 10th century. The elaboration of trigonometry, which was considered to be a branch of astronomy at that time, was also continued. A great attention was paid to the construction of good astronomical instruments, especially to the spherical astrolabe which was newly introduced at that time. Hamid Ibn ‘Ali was a famous constructor of spherical astrolabes. Jãbir Ibn Sinan was also a maker of this as well as of other astronomical instruments. According to al-Biruni, he was the first to make a spherical astrolabe. Al-Nairizi wrote on this instrument an elaborate treatise which represents the best Arabic work on this topic. In this treatise the author, after giving the introduction, describes the instruments, and gives its applications. Beside this work, al-Nairizi compiled astronomical tables. A great scientist al-Mähani made for 33 years (833—886), a series of observations on lunar and solar eclipses and planetary conjunctions. Another astronomer of this time Ahmad al- Nahâwandi, who flourished at the time of Yahya Ibn Khalid Ibn Barmak, made astronomical observations at Jundishapur and compiled tables called Mushtamil. (16)
After carrying out astronomical observations for ten years (825 to 835) Habash al-Hãsib compiled three astronomical tables. The first were according to the Hindu method (based on Siddhanta). The second called Al-Zij al-Mumtahan (the “tested Tables”) were according to the Arab method. They were very important and were probably due to the co-operative efforts of al-Ma’mun’s astronomers. The third called Al-Zij Al-Saghir (the small tables) was commonly known as the Tables of Shah. Habash al-Hãsib determined the time of the solar eclipse of the year 829. He was the first to determine time by an altitude (in this case, of the sun). This method was generally accepted and adopted by Muslim astronomers. (17)
The most illustrious scholar of this age, and one of the greatest astronomers of Islam, was ‘Abd Allah Muhammad Ibn Jãbir Ibn Sinan al-Battãni (Latin; Albategnius, Albatenius). His ancestors were Sabeans of Harran, but he himself was a Muslim. He carried out astronomical observations of a wide range and with remarkable accuracy for about 41 years (877—918). He determined many astronomical co-efficients, like the precession 54.5” a year, inclination of the ecliptic 23° 35’, with great accuracy. He noticed an increase of 16° 47’ in the longitude of the sun’s apogee since Ptolemy’s time. This led to the discovery of the motion of the solar apsides and of slow variation in the equation of time. Al-Battãni proved the possibility of the annular eclipses of the sun. He also wrote many astrological works. His main work is a large astronomical treatise including the astronomical tables. His tables contain a catalogue of fixed stars for the year 880—81. His work is an advance on that of al-Khwãrizmi, and shows more divergence from Indian methods. Observations regarding the first appearance of the new moon, the length of the tropic and sidereal year, the obliquity of the ecliptic, the lunar anomalies, the parallaxes, etc., are more complicated and more accurately made by al-Battãni than by al-Khwãrizmi
Al-Battãni’s astronomical treatise was translated into Latin and Spanish in the 12th and 13th centuries respectively. It exerted a great influence on the European scholars of the middle Ages and Renaissance. (l8)
Thãbit Ibn Qurrah (d. 901) who was a physician, mathematician, astronomer and translator from Greek and Syriac into Arabic published his solar observations made at Baghdad. He particularly determined the altitude of the sun and the length of the solar year. (19)
The astronomer and mathematician Wijan Ibn Rustam al-Kühi wrote many astronomical and mathematical works, including a treatise on the construction of the astrolabe. He was the head of the astronomers working in 988 at the Buwayhid Sharaf al-Dawlah’s observatory. (20) His co-worker Ahmad Ibn Muhammad al-Saghâni was the inventor and maker of astronomical instruments. Abu’l-Wafã is said to be the discoverer of the variation, the third inequality of the moon; a discovery which was later ascribed to Tycho Brahe. (21)
‘Ali Ibn al-Husain al-’Alawi (d. 985) showed a remarkable accuracy in observations. He compiled astronomical tables which remained very popular for at least two centuries. (22)
Now we come to a famous astronomer of the 10th century, named Abu’l-Husain ‘Abd al-Rahman al-Sufi. He was born in Ray (Persia) in 903, and died in 966. He was a prominent astronomer of the medieval times. His knowledge of both the Islamic and Greek astronomy, particularly uranometry, was comprehensive. He was the first to observe the change of the colour of stars, the change in the magnitude of stars, the proper motion of stars, the long period variable stars and the Southern constellations which have been wrongly ascribed by modern astronomers to some later ones.
Abd al-Rahman al-Sufi was patronized by the Buwayhid ruler Adud al-Dawlah (949—982) who was a great patron of astronomy, and had built an observatory at Shiraz. Al-Sufi wrote for the ruler a book on uranometry, entitled Suwar al-Kawàkib (The book of the fixed stars). In this book he gives a complete description of the constellations of the heavens. He also gives the position of each star of the constellations, illustrating with pictures. The book contains 55 astronomical tables along with illustrations of 48 constellations in 96 diagrams as seen in the heavens. The artistic value of the pictorial illustrations in the Mss. of this work is very great, and represents one of the best examples of the Persian miniature paintings. Al-Sufi has not only corrected the errors of observations in the work of his predecessors like al-Battãni, but also, pointed out many faulty observations found in Ptolemy’s Almagest. He defined carefully the boundaries of each constellation, and recorded the magnitudes and positions of stars after making new observations.
The Suwar al-Kawàkib is one of the three masterpieces of observational astronomy of the medieval times; the other two being the catalogues of Ibn Yünus and Ulugh Beg prepared in the 12th and 15th centuries respectively. It is an addition to the Muslims’ knowledge on uranometry. The later astronomers, like al-Biruni, Alfonso, Prince of Castile, Khwãjah Näsir al-Din Tusi, Prince Ulugh Beg and Jai Singh II, based their catalogues of stars on this authentic catalogue. This work was translated into Latin, French and Persian, and a commentary on it was written in Spanish.
It served as a basis for later works in Western Europe. The modern astronomers like Hauber, Down, Argelander, Ideler, Schellerup and Knobel had made an extensive use of it.
Al-Sufi prepared a fine celestial globe. Several celestial globes which cover the period from the 11th to the 18th century show the star positions and magnitudes according to al-Sufi. He showed a remarkable accuracy in the design of the astrolabes. He wrote a treatise on this instrument. In this treatise he throws light on the astronomical techniques as practiced it that time. (23)
Another great astronomer and one of the greatest Muslim astronomers was Abu’l-Hasan Ali Ibn Abi Said ‘Abd al-Rahman Ibn Ahmad Ibn Yünus al-Sadafi, generally known as Ibn Yünus. He was well versed in Arabic literature, poetry and history, and had knowledge of many other subjects. He belonged to Egypt where he died in 1009. He was a courtier of the Fatimi Caliph al-‘Aziz Billah (975—996). He got a chance of working in a well-equipped observatory which was the part of a Muslim academy of science, named Dar al-Hikmah (the house of wisdom) founded in Cairo by the Fatimi rulers. He made astronomical observations, and by the order of the Caliph al-‘Aziz he compiled the astronomical tables. The work of compilation of these tables was begun in 990 during the lifetime of the Caliph, but it was completed after his death under his son al- Hakim (966—1020). Hence they were named after him Al-Zij al-Kabir al-Hakimi. In these tables he entered his observations about the eclipses and conjunctions, old and new, improved values of astronomical constants (inclination of the ecliptic, 23° 35’; longitude of the sun’s apogee, 86° 10’; solar parallax reduced from 3’ to 2’; precession, 51.2” a year). He gave an account of the geodetic measurements which were carried on by the order of the Caliph al-Ma’mun in the ninth century.
Ibn Yünus in his astronomical tables (written in 4 volumes) corrected the errors of observations in the astronomical tables of his predecessors. The people of Egypt relied on these tables. It is said that after their compilation the use of all the previous tables in the world was given up. Even the astronomers of China greatly utilized them. The translation of a large part of the tables, except the chronological section, has been made in French in 1804.
Beside these-tables, Ibn Yünus has composed many books. One of these is Jadawil al-Samt (the tables of direction), and the other is the Jadawil al-Shams wa’l-Qamar (the tables of the sun and the moon). (24)
A famous astronomer of the 11th century, who belonged to Cordova (Spain), was Abu Ishaq Ibrahim Ibn Yahya al-Naqqàsh, commonly known as Ibn al-Zarqàli or al-Zarqàli (Latin: Arzachel). He was also an eminent astronomer of this century. He lived from 1029 to 1087. He was the best observer of his time, who made astronomical observations for about 19 years (1061—1080). He invented an improved astrolabe called Safihah (Saphaea Arzachelis) on which he also wrote a treatise. It was translated into Latin, Hebrew and many vernaculars. Al-Zarqàli was the first to prove explicitly the motion of the solar apogee with reference to the stars. According to his calculations it was equal to 12.04” per year (the real value being 11.8”). He edited the planetary tables called Toledan Tables. These tables were probably the result of the observations made in Toledo by him and by a great observer Ibn Said in collaboration with other Muslim and Jewish astronomers. They were translated into Latin and enjoyed much fame. (25)
A famous astronomer, mathematician and poet, ‘Umar Ibn al-Khayyãm, reformed the old Persian calendar which had been replaced by the Islamic calendar after the Muslim conquest of Persia. This reformed calendar was called Al-Tàrikh al-Jalãli after the name of the Saljuq Sultan Malik Shah Jalal al-Din who in 1074-75 called ‘Umar Ibn al-Khayyãm to his observatory for making this reform. Many interpretations have been given to it. Each interpretation is accurate to a certain degree, but at any rate ‘Umar’s calendar was probably more accurate than the Gregorian (Christian) calendar. Three interpretations, the second of which seems to be the most accurate, are being quoted here along with the authority giving the interpretation and the resulting error.
1. Al-Shirãzi’s interpretation: 17 intercalary days in 70 years;’ error. 1 day in about 1540 years.
2. Ulugh Beg’s interpretation: 15 intercalary days in 62 years; error, 1 day in about 3770 years.
3. Modern interpretation: 8 intercalary days in 33 years: error, 1 day in about 5,000
(in the Gregorian calendar there is an error of 1 day in 3330 years). (26)
The greatest astronomer of the 12th century, who also belonged to Spain, was Abu Muhammad Jãbir Ibn Aflah. He was born or lived in Seville. He vigorously criticized the Ptolemaic theory of planets, and wrote a book on astronomy entitled Islah al-Majisti (the correction of the Almagest). He was of the view that the lower planets Mercury and Venus), at least, must have visible parallaxes. Venus may happen to be exactly on the line joining the sun and the earth. The most important part of his book is the introduction on trigonometry. The book was soon translated into Latin and Hebrew. Jãbir Ibn Aflah is said to be the inventor of the astronomical instrument called turquet (torquetum) which contains two graduated circles in two perpendicular planes. The same invention has also been ascribed to two other persons, namely, Frances of Leige (11th century) and Näsir al-Din Tusi (13th century). The turquet was introduced into the Latin West by Regionomentus. It gained a great popularity in the 15th and 17th centuries. (27)
Another astronomer of the time was Abu’l Qãsim Hibat Allah Ibn Husain al-Badi’ al-Asturlãbi. He was also a physician, mathematician, poet and litterateur. He was the greatest expert of his time in the knowledge and construction of astrolabes; hence his nickname al-Asturlãbi. In 1120—30 astronomical observations were made under his direction, and astronomical tables were compiled. The observations were carried out in the palace of the Saljuq Sultan of Iran, Mughith al-Din Mahmud (1117—1131). The tables were dedicated to the Sultan, and were called after him the Mahmudic tables. Al-Asturlãbi was very much praised by Muslim biographers. He died in Baghdad in 1139-40. (28)
In the 13th century there flourished in the East a great scholar of Persian origin, named Abu Ja’far Muhammad Ibn Muhammad Ibn al-Hasan, Näsir al-Din al-Tusi al-Muhaqqiq, (the researcher). He was born in Tus (Khurasan) in 1201, and died in Baghdad in 1274. He was a philosopher, mathematician, astronomer and physician. He was one of the greatest Muslim mathematicians and scientists. He wrote both in Arabic and Persian. It is said that he knew Greek as well. He joined the Mongol service, and was later made administrator of the Waqf revenues.
While he was administrator he resided at Maragha in Asia Minor (1259—1274). Here he made astronomical observations in an observatory established by the Mongol ruler Hulagu Khan II after he had defeated the last ‘Abbasi Caliph, al-Mu’tasim, in 1258. A library was attached to it. It is said to have contained 4, 00,000 volumes which the Mongol armies had collected in Syria, Mesopotamia and Persia. Näsir al-Din was the first director of this observatory. He was succeeded by two of his sons.
Näsir al-Din was well acquainted with the knowledge of the Greeks. He wrote about 64 works on many subjects. Here we shall, consider only some of his astronomical and astrological works. The most important astronomical work of Näsir al-Din is the Tadhkirah fi ‘Ilm al-Hay’ah (The description of astronomy) which is a condensed summary of astronomy. To explain it many commentaries and super commentaries have been written. The work enjoyed much popularity, it consists of four chapters. The second chapter, beside other things, contains interesting criticism of the Ptolemy’s Almagest in which he showed a great ingenuity. The criticism chiefly concerns the anomalies of the moon, and the motion in the latitude of the planets (particularly Mercury and Venus) ; also the proposition of a new system to replace the complicated Ptolemaic machinery of deferents and epicycles. His new and forceful criticism of astronomy as well as of other Muslim astronomers helped Copernicus in making his reform’. Näsir al-Din wrote one treatise on the five quadrants and two treatises on astrolabe. He also wrote two treatises on calendar.
Näsir al-Din made observations in the observatory at Maragha which was well equipped with good astronomical instruments. He prepared new astronomical tables called after the Mongol ruler, Al-Zij al-Ilkhäni. Nasir al-Din asked the ruler to give him a period of 30 years to compile the tables, because it was the shortest period during which the planetary cycles were completed. But the ruler refused, and gave him only 12 years to accomplish this task. Nasir al-Din tried a succeeded in completing the tables within this time. They were based upon new observations. But the use of the earlier ones had also been made.
The Zij-i- Ilkhäni was originally written in Persian. It consists of four books dealing respectively with (a) Chinese, Greek, Arabic and Persian Chronology; (b) motions of the planets; (c) ephemeredes and (d) astrological operations. The translation of the Zij was made into Arabic, and commentaries on it were written. Finally, a sort of supplement to it was compiled by Jamshed Ibn Mas’üd al-Käshi (d. 840/1436), the first director of Ulugh Beg’s observatory in Samarqand. These tables enjoyed a great popularity in the East including China, and were, continued to be used even after the compilation of new tables by Ulugh Beg in 1437. (29)
A contemporary of Nasir al-Din, Mu’ayyid al-Din al-Urdi al-Dimashqi also took part with him in compiling the tables. He was a Syrian astronomer, architect and engineer. He started his career as a technician in Syria. He did some hydraulic work in Damascus, and also constructed there an astronomical instrument for al-Mansür Ibrahim (King of Hims, 1239—1245). In about 1259 he went to Maragha, and helped Nasir al-Din in organizing the observatory and compiling the tables. It seems that the instruments, remarkably precise, were constructed under his supervision in the foundry attached to the observatory.
Al-Urdi was the author of a treatise in which he also described the instruments used in the observatory of Maragha, and explained their use and construction. The instruments are as follows:—
(1) mural quadrant (2) armillary sphere (3) solstitial armil (4) equinoctial armil (5) Hipparch’s diopter (alidade); (6) instrument with two quadrants (7) instrument with two limbs (8) instruments to determine sines and azimuths (9) instruments to determine sines and versed sines, (10) the perfect instrument (a universal instrument) (11) parallactic ruler (after Ptolemy).
Al-Urdi was also the author of two other treatises; one on the construction of a perfect sphere and another on the determination of the distance between the centre of the sun and the apogee. He compiled astronomical tables, and wrote on Ptolemaic astronomy.
In 1279 or 1289 al-Urdi’s son Muhammad made a celestial globe. It consisted of two brass hemispheres separated by the ecliptic. Its diameter was 140 mm. It had a horizon circle. Two movable half circles were attached to the zenith point by a pivot. These circles are graduated and are used to determine the declination and right ascension of any star. Forty-eight constellations, the equator and the ecliptic are inlaid with silver or gold. It is preserved in the mathematical salon of Dresden. (30)
The works of Muslim astronomers were later translated into Latin, Hebrew and vernaculars by the Christian and Jewish scholars, some of the technical terms including azimuth (al-Samt), Algol (Alfol), Achernar (Akhir al-Nahr), passed into the European languages. The names of many stars such as akrab (Aqrab), Algedi (al-Jadi, the kid), Altair (al-ta’ir ,the player), Denab (dhanb, tail), Pherkad (Farqad, calf), Adara (‘Adhrah) Aldebaran (al-dibràn), which are of Arabic origin, also passed into these languages. The stars being countless in number, their separate study is not possible. They were, therefore, divided into various groups, and the groups were named after the things and animals with which they resembled.
REFERENCES :-
1. Briffault, Robert , The Making of’ Humanity, Lahore, 1980, p. 187.
2. Encyclopedia Britannica, London, Vol. II, p.575.
3. Abu’l Hasan Ali Ibn Yusuf , Al-Qifti , Tàrikh al-Hikmah,’ Leipzig, 1903, p. 265.
Sarton, George, Introduction to the History of Science, Washington 1927, vol. I. p. 530.
4. Ibid.
5. Ibid, p. 563.
6. Al-Qifti, op. cit., 57.
7. Ibid., p. 327.
Sarton, op. cit. p. 531.
8. Ibid.
9. Ibid. p. 557.
Haji Khalifah, Kashf al-Zunün, Istanbul, 1943, vol. II, p. 1594.
10. Sarton, op. cit., p. 562.
11. Ibid, p. 558.
12. Shibli Nu’mani, Al-Ma’mun, Agra, 1894, pp. 49— 50,
13. Ibn Nadeem, Al-Fehrist, Matba’ah al-Rahmaniyah, Cairo, n.d.. p. 383.
14. Shibli Nu’mani, op. cit. pp. 49—50
Sarton, op. cit. p. 566.
15. Ibid.
16. Sarton, op. cit.. p. 585.
17. Al-Qifti, op. cit. p. 170.
18. Ibid, p. 280.
Sarton, op. cit. p. 5858.
19. Ibid., p. 599.
20. Al-Qifti, op. cit. p. 351.
21. Sarton, op. cit. p. 666.
22. Ibid.
23. A1-Süfi, ‘Abd al-Rahman, Swar al-Kawàkib, Hyderabad, preface by M. Nizamuddin, and J.J. Winter, pp. 1-7.
24. Al-Qifti, op. cit., p. 226.
25. A1-Qifti, op. cit., p. 230.
26. Sarton, op. cit., p. 758,
27 Ibid., p.759
28. Ibid, vol. II, part I, p. 206.
29. Ibid., part I, p. 204.
30. Al-Baghdadi, Isma’il Bãshã, Hadiyyat al-‘Arifin, Istanbul, 1951, vol. II, p. 131.
31. Sarton, op. cit. vol. II, part II, p. 1005.
32. Ibid., pp. 1013-1014.
By: Md. Wasim Aktar
Deptt. of Agril. Chemicals, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India.
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