In calendar: Complex cycles …cycle was improved by both Callippus and Hipparchus. Callippus of Cyzicus (c. 370–300 bce) was perhaps the foremost astronomer of his day. He formed what has been called the Callippic period, essentially a cycle of four Metonic periods. It was more accurate than the original Metonic cycle and made use… Read More
theory of homocentric spheres
In physical science: Ancient Middle Eastern and Greek astronomy The system was modified by Callippus, a student of Eudoxus, who added spheres to improve the theory, especially for Mercury and Venus. Aristotle, in formulating his cosmology, adopted Eudoxus’s homocentric spheres as the actual machinery of the heavens. The Aristotelian cosmos was like an onion consisting of a series of… Read More
