Shu-ging (1231-1316) - astronomer and mathematician who improved the tables of the Sun and Moon. He made new measurements of the Sun and the solstices, and added new instruments to observing. Sina, Abu-Ali Al-Husain ibn Abdullah ibn (980-1037) - also known as Avicenna, a physician and philosopher. He made stellar observations and wrote on astronomy and Ptolemy. Sosigenes (c. 50 BC) - Greek astronomer whose is most known for convincing Julius Caeser to abandon the lunar calendar in use for the solar calendar. A modified version of this calendar is still in use today. Ssu-ma Chi'en [Sima Qian] (145-90 B.C.) - historian and astronomer who completed tables of the position of the Moon.