acoreus aglaonike anaximander andronicus of cyrrhus antikythera mechanism apollonius of perga applied mathematics aratus aristarchus of samos aristillus armillary sphere astrolabe astronomy in medieval islam attalus of rhodes autolycus of pitane babylonian astronomy bion of abdera callippic cycle callippus celestial spheres circle of latitude cleomedes cleostratus conon of samos counter-earth deferent and epicycle dioptra egyptian astronomy equatorial ring equidimensional eratosthenes euctemon eudoxus of cnidus geminus geocentric model gnomon greek astronomy heliocentrism heraclides ponticus hicetas hipparchic cycle hipparchus hippocrates of chios hypsicles indian astronomy menelaus of alexandria meton of athens metonic cycle mural instrument nicolaus copernicus octaeteris oenopides philip of opus philolaus posidonius ptolemy pytheas science in medieval western europe seleucus of seleucia solstice sosigenes of alexandria sosigenes the peripatetic spherical earth strabo sublunary sphere thales theodosius of bithynia theon of alexandria theon of smyrna timocharis tusi-couple zodiac