(Ἀρίσταρχος), of SAMOS , one of the earliest astronomers of the Alexandrian school. We know little of his history, except that he was living between B. C. 280 and 264. The first of these dates is inferred from a passage in the μεγάλη σύνταξις of Ptolemy (3.2, vol. i. p. 163, ed. Halma), in which Hipparchus is said to have referred, in his treatise on the length of the year, to an observation of the summer solstice made by Aristarchus in the 50th year of the st Calippic period : the second from the mention of him in Plutarch (de Facie in Orbe Lunae), which makes him contemporary with Cleanthes the Stoic, the successor of Zeno.
[W.F.D]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890