SOSIGENES, Greek astronomer and mathematician, probably of Alexandria, flourished in the 1st century B.C. According to Pliny (Nat. Hist, xviii. 25), he was employed by Julius Caesar in the reform of the Roman calendar (46 B.C.), and wrote three treatises, which he conscientiously corrected. From another passage of Pliny (ii. 8) it is inferred that Sosigenes maintained the doctrine of the motion of Mercury round the Sun, which is referred to by his contemporary Cicero, and was also held by the Egyptians.
The astronomer is to be distinguished from the Peripatetic philosopher of the same name, who lived at the end of the 2nd century A.D. He was the tutor of Alexander of Aphrodisias, the most famous of the commentators on Aristotle. He wrote a work on Revolving Spheres, from which some important extracts have been preserved in Simplicius's commentary on Aristotle's De caelo (the subject is fully discussed by T. H. Martin, " Sur deux Sosigene," in Annales de lafac. des letlres de Bordeaux, i., 1879).
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)