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.

The Muslims looked upon astronomy as the noblest, the most exalted and the most beautiful of sciences because the study of the stars was an indispensable aid to religious observance. Arabic astronomy was subdivided into 4 main parts: spherical astronomy, chronometry, spherical trigonometry and mathematical geography.

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, peace and blessings be upon him, from Mecca to Medina in A.D. 622. This event, called the Hegira, marks the beginning of the Islamic calendar. The early centuries of Islam were characterized by a rapid 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, but he was tolerated in the Islamic capital. There he wrote more than 100 scientific treatises, including a commentary on the Almagest.

Under the reign of al-Ma’mun (ninth century), astronomers of the Baghdad and Damascus observatories busied themselves with verifying and correcting Ptolemy’s tables, and established the so-called Verified Astronomical Tables of Yahya ibn Abi Mansur (A.D. 830). Unlike Ptolemy’s, these Tables took into account the precession of the equinoxes. Observations of Venus and the sun led the same astronomers to adopt a non-Ptolemaic model which led them to believe that the orbit of Venus was an epicycle with a constant center.

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.

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.

Impact of these advancements on the Renaissance

The advancements made by the Muslims in the field of Astronomy had much impact on the Renaissance. Firstly, there ideas concerning the orbits of the planets were the base for the many renaissance scientists who were to investigate the heavens and eventually conclude a number of things that we now take for granted, such as the fact that the Earth spins on its own orbit and the sun, not the Earth, is in fact the center of our universe. Secondly, their advancements in trigonometry had a huge impact on many fields of Renaissance science. Using these concepts of trigonometry, the European scientists expanded upon them and came up with more complex formulae and equations. Additionally, they also utilized trigonometry to construct increasingly complex machines and devices that subsequently led to further discoveries.

The Muslims’ impact on navigation was also felt in the Renaissance. European navigators relied on the Muslim concepts to develop their own theories and methods of navigation, methods that would eventually allow them to explore distant lands by sea. Finally, Muslims’ astronomy was expanded upon throughout the Renaissance, and we continue to see a form of it in everyday life, in our newspapers and magazines.

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Source:

Islamic astronomy by Owen Gingerich.

Islamic-paths.org

Britannica.com