Thabit ibn Qurra

Thabit ibn Qurra (836 - 901), an astronomer and mathematician born in present day Turkey, best known for translating classic Greek works on astronomy, and for coming up with a formula for amicable pairs.

Muhammad bin Musa bin Shakir invited Thabit to work in Baghdad's House of Wisdom translating Greek and Syrian works (such as Apollonius's Conics or works of Euclid and Archimedes). As he translated the texts, Thabit produced a mathematical body of his own.

Thabit was one of the Sabians. Their worship of planets and stars was tolerated by the Muslim caliphs, who were interested in their work on astronomy. It is believed that Thabit came up with early theories about the equinoxes, and made a pretty good estimate of the length of the sidereal year that was off by just a couple of seconds.

Thabit's son was a doctor, and his grandson studied curves in order to make better sundials.