Aristarchus of Samos, Greek astronomer, flourished about 250 B.C. He is famous as having been the first to maintain that the earth moves around the sun. On this account he was accused of impiety by the Stoic Cleanthes, just as Galileo, in later years, was attacked by the theologians. His only extant work is a short treatise (with a commentary by Pappus of Alexandria) On the Magnitudes and Distances of the Sun and Moon. His method of estimating the relative lunar and solar distances is geometrically correct, though the instrumental means at his command rendered his data erroneous. Although hte heliocentric system is not mentioned in the treatis, a quotation in the Arenarius of Archimedes from a work of Aristarchus proves that he anticipated the great discovery of Copernicus. Further, Copernicus could not have known of Aristarchus's doctrine, since Archimedes's work was not published till after Copernicus's death. Aristarchus is also said to have invented two sun dials, one hemispherical, the so called scaphio, the other plane.
From the eleventh edition of The Encyclopedia, 1911. Public domain. The name of the encyclopedia is still a registered trademark, and is therefore not listed here. Some spellings have been changed to reflect the times (and link better), and some notes have been removed, most of which referred to other articles, and have been replaced with links.