Eudoxus

Eudoxus of Cnidus, called by Cicero the prince of astronomers, flourished about 370 B.C. He studied under Plato for some time, and afterwards went to Egypt, where he derived much knowledge from the priests. He is said to have introduced an astronomical system of homocentric spheres into Greece, and the year of 365½ days, likewise to have distinguished true astronomy from astrology.