Ibn al-Shatir

Ala al-Din Ali ibn Ibrahim ibn al-Shatir worked as chief timekeeper (muwaqqit) at the Great Umayyad Mosque of Damascus. A master craftsman of astrolabes, quadrants, and sundials, he constructed a magnificent horizontal sundial for the mosque's northern minaret that was a marvel of medieval precision engineering.

In his seminal astronomical treatise Nihayat al-Sul fi Tashih al-Usul, Ibn al-Shatir eliminated the problematic equant of Ptolemaic planetary theory by introducing sophisticated epicyclic models. Modern historians of science discovered in the 1950s that Nicolaus Copernicus used mathematically identical models for the Moon, Mercury, and Venus, showing direct transmission from Damascus to Renaissance Europe.