Mu'ayyad al-Din al-'Urdi

Who was Mu'ayyad al-Din al-'Urdi?

Mu’ayyad al-Din al-’Urdi was an Muslim astronomer, mathematician, architect and engineer working at the Maragheh observatory. He was born in Aleppo,todays Syria, and later moved to Maragheh, Azarbaijan, to work at the Maragha observatory under the guidance of Nasir al-Din Tusi.

He is known for being the first of the Maragha astronomers to develop a non-Ptolemaic model of planetary motion. In particular, the Urdi lemma he developed was later used in the geocentric model of Ibn al-Shatir in the 14th century and in the heliocentric Copernican model of Nicolaus Copernicus in the 16th century.

As an architect and engineer, he was responsible for constructing the water supply installations of Damascus, Syria, in his time.