Aristarchus of Samos (309–229 BCE)
Born 309 BCE, died 229 BCE.
Aristarchus of Samos (; Ancient Greek: Ἀρίσταρχος ὁ Σάμιος, Aristarkhos ho Samios; c. 310 – c. 230 BC) was an ancient Greek astronomer and mathematician who presented the first known heliocentric model that placed the Sun at the center of the universe, with the Earth revolving around the Sun once a year and rotating about its axis once a day. He also supported the theory of Anaxagoras that the Sun was just another star. Born in Samos in approximately 310 BC, Aristarchus likely moved to Alexandria and became a student of Strato of Lampsacus, who later became the head of the Peripatetic school in Greece. According to Ptolemy, Aristarchus observed the summer solstice of 280 BC. Vitruvius writes that Aristarchus built two different sundials: one a flat disc; and one hemispherical. Aristarchus estimated the sizes of the Sun and Moon as compared to Earth, and the distances from the Earth to the Sun and to the Moon.
Text from the Wikipedia article Aristarchus_of_Samos, licensed CC BY-SA 4.0.