Copernicus and the Muslim Astronomical Tradition

February 19, 2013 1 Comment

Today we wish happy birthday to the Polish scientist Nicholas Copernicus, whose publication in 1543 of the heliocentric model of the universe is viewed as a landmark achievement in Western thought.


In fact, the story of this Copernican Revolution, completed by Kepler’s work on elliptical orbits and, later, Newton’s theory of gravitation,  provides one of the totemic moments in the “classical” understanding of Western history of science.

Yet, overlooked in the primordial urge of historians to find the “zero point” of modern, Western consciousness is the crucial preparatory work carried out by generations of earlier astronomers and mathematicians working in an entirely different intellectual world — that of Islam. The only “original” theorems in Copernicus’s great De Revolutionibis have been traced back to Muslim scholars seeking to correct the deficiencies of classical cosmology.

Dissatisfied with the prevailing Ptolemaic model of an earth-centered universe, Muslim scholars — scientists and philosophers alike — began a systematic critique of Classical cosmology as early as the eleventh century. Averroes, the great jurist and philosopher, summed up the scholarly objections, as follows: “The science of (Ptolemaic) astronomy of our time contains nothing existent, rather the astronomy of our time conforms only to computation and not to existence.”

Astronomers at the observatory at Maragha, in what is today northwest Iran, made a number of breakthroughs to address the shortcomings they had detected in classical cosmology. Nasir al-Din Tusi, the observatory’s director, devised an ingenious way to generate the apparent linear motion of the planets from the uniform, circular motion that Ptolemy demanded from all celestial bodies.  His assistant solved the same problem in a different way, and the two methods were later harmonized by Ibn al-Shatir, timekeeper at the Umayyad Mosque in Damascus.

Ibn al-Shatir died in 1375, 168 years before the achievements of the Maragha astronomers appear in the groundbreaking work of Copernicus, strongly suggesting that the Polish scientist and churchman must have been familiar with the cutting-edge research of his Arab predecessors. However, no known pathway of direct transmission has yet been established, although Copernicus did study in Italy, where Arab science and philosophy still enjoyed serious study.

Neither Ibn al-Shatir nor Tusi ever suggested a heliocentric universe, although other Muslim scholars at least contemplated. But it is worth noting that Ibn al-Shatir had already shown that it was possible for the celestial bodies to be made to rotate in uniform circular motion around a single point. This made Copernicus’s breakthrough much easier by allowing him to establish that point as the sun without having to reinvent an entire planetary model from scratch.

By properly locating Copernicus, whose birthday we celebrate on February 19, along a continuum of world scientific efforts we can break down the artificial history of Western science that has claimed his achievements as its exclusive province. It also serves as a powerful reminder that “Islam” and the “West” are in fact part of a single cultural space, locked in rivalry but hardly as alien from one another than either side likes to claim.




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Copernicus; a Revolution or a Re-Evaluation [Hamza] | History of Science, April 4th, 2016 on 9:52 am

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