#e <t>pub<au>Euclid<tit>Catoptrics<info>states the law of reflection<d>300(10)
#p <nat>Greek<o>astronomer<n>Aristarchus<c>Samos<b>310(10)<d>230<info>first argued that earth revolves around sun
#e <t>theory<d>260<c>Samos<n>heliocentric theory<info>Aristarchus pointed out, in 260 B.C., that the motions of the planets, sun, moon and stars could be accounted for if it were assumed that all the planets, including the Earth, orbited about the sun.
// 3rd century B.C.
#p <nat>Greek<o>astronomer<n>Eratosthenes<b>276(2)<d>197<c>Alexandria<info>Eratosthenes devised a prime number sieve.
#p <nat>Greek<o>astronomer<n>Hipparchus<c>Rhodes<b>190<d>120<info>His estimates of the moon's size and distance relative to Earth were remarkably accurate for his time.
#e <t>theory<au>Hipparchus<d>150(20)<n>epicyclic theory<c>Rhodes<info>Hipparchus developed the system of epicycles describing planetary motion, which helped preserve the geocentric model of the universe.
#p <nat>Greek<o>astronomer<n>Ptolemy Claudius<aka>Claudius Ptolemaeus<sur>Ptolemy<b>100(10)<d>170(10)<c>Alexandria<info>Ptolemy was an astronomer who was active in Alexandria between A.D. 127 and 141. He put together his own ideas, those of Aristotle, and Hipparchus' system of epicycles and eccentric circles, to formulate the geocentric theory.