Islamic Civilization and Astronomy

85:18

18 Sep 2012

Astronomy, History of Science

George Saliba

George Saliba, professor of Arabic and Islamic science at Columbia University, New York, discusses the role(s) played by science in the medieval Islamicate world.  He sets out to debunk two myths about “Islamic science” — that it only carried forward Greek scientific ideas, and that “modern science” was created sui generis in Europe during the Renaissance.

To debunk these ideas he discusses “the critical role of Arabic astronomy” in the development of Renaissance science.  He discusses the role of astronomical observation in determining the time for the daily prayers, citing verses 2:232-238 of the Qurʾān.  Mathematical developments were needed in order to determine the time for the afternoon prayer.  He discusses how 9th century Baghdadi Muslim scholars realized the problems with Ptolemy’s observational strategies, and developed their own methods for determining the solar apogee.  The other problem that needed to be worked out in relation to prayer was determining the direction of prayer.  This required spherical geometry and computing latitude and longitude lines.  Scholars also tried to develop new projections of maps with Mecca at the center in order to assist pilgrims to determine how far they would need to travel for the ḥajj to Mecca.  As they moved through Greek geometry, they started to correct the factual and theoretical problems they found that did not match their observations.  Ibn al-Haytham wrote “Doubts on the Works of Ptolemy” to try to bring together physics and mathematics.  Saliba points out the similarities between Ibn al-Shatir’s solutions to the size of the moon and those of Copernicus (d. 1543).  ʿUrdī (d. 1266, Damascus) also creates models (“the ʿUrdī Lemma”) that are similar to those of Copernicus.  Saliba pointedly suggests that Copernicus copies Ibn al-Shatir’s models, even without quite understanding them.  He also demonstrates similarities between a model developed by Nasīr al-Dīn al-Ṭūsī (d. 1274) and those of Copernicus.  He wraps up his discussion by noting that the algebra that had been developed in the Islamic world wasn’t uniformly picked up in Europe.  For instance, Galileo didn’t seem to use Islamic algebra.

Saliba closes by saying that it’s important to try to extract the development of scientific ideas from the “cultural bragging”, both from Europeans and Muslims.

Concepts discussed:  trigonometry, development of astronomical instruments to measure the motion of the stars (including that of Ulugh Beg in the 15th century), rotation of spheres on their axes, mathematics of spheres, Ibn al-Shatr (d. 1375) on the size of the moon, Nasīr al-Dīn al-Ṭūsī (d. 1274) and planetary motion

The lecture was given at the Library of Alexandria, Egypt, on the occasion of the 20th meeting of the International Planetarium Society.  This keynote lecture was delivered on 29 June 2010.

Evaluation:

The material on Islam is within the bounds of what Muslims have historically understood as acceptable.

The material on the history of science is based on well-researched materials.  The correspondences in the models, one must note, need not necessarily mean that a later scholar extracted the information from an earlier scholar, although it is possible.  Additional work on the dissemination of the Arabic scientific material among European scholars may help us understand more completely the transferences among these scholars.