c. 310–230 BCE · astronomer

Aristarchus of Samos

Ἀρίσταρχος ὁ Σάμιος

Known · AttestedNot attested in Alexandria.

The first known to put the Sun at the centre, with the Earth going round it; Archimedes, a younger contemporary, reports the hypothesis, and Plutarch adds that the Earth also turned on its own axis. His surviving On the Sizes and Distances of the Sun and Moon is a geometry of eclipses. He was a pupil of Strato, who had tutored Ptolemy II; that he worked in Alexandria is likely but not stated.

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Archimedes tells the hypothesis in passing: the fixed stars and the Sun do not move, the Earth goes round the Sun in a circle, and the sphere of the stars is so vast that the Earth's circle is as a point beside it (Sand-Reckoner 1.4–7). Plutarch adds that Cleanthes the Stoic thought Aristarchus should be charged with impiety for moving the hearth of the world (On the Face in the Moon 6). His surviving book uses the half-moon and eclipses to find the sizes of the Sun and Moon; it puts the Sun more than eighteen and less than twenty times further than the Moon, far short of the truth but the earliest such proof to survive. Archimedes sets it beside earlier figures for the Sun's diameter against the Moon's, about nine times from Eudoxus and twelve from Phidias, Archimedes' own father, which he records without their reasoning (Sand-Reckoner 1.9). Vitruvius names him among the rare men who mastered every branch of mathematics, and reports that the bowl sundial (scaphe or hemisphere) and the disc on a plane were said to be his inventions (On Architecture 1.1.17; 9.8.1).

Our device: No portrait of any of these people survives. The emblems are our devices.

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