1911 Encyclopædia Britannica/Aristarchus (of Samos)
ARISTARCHUS, of Samos, Greek astronomer, flourished about 250 B.C. He is famous as having been the first to maintain that the earth moves round 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) 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 the heliocentric system is not mentioned in the treatise, 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 scaphion, the other plane.