Aristarchus of Samos on the Sizes of the Sun and Moon

Aristarchus of Samos was an ancient Greek astronomer and mathematician who flourished around 280 BCE. He was a student of Strato of Lampsacus, connecting him to the Lyceum and the early Hellenistic scientific tradition. Beyond this association, few biographical details survive.

Only one of his works survives complete: On the Sizes and Distances of the Sun and Moon, a geometrical treatise calculating celestial distances from lunar phases. He is most famous for his heliocentric hypothesis, which placed the Sun at the centre of the cosmos with a revolving Earth. This revolutionary model is not preserved in his own writings but is reported by later authors like Archimedes and Plutarch.

Aristarchus entered the history of astronomy with this early heliocentric theory, a radical departure from dominant geocentric models. Though not accepted in antiquity, it was a profound conceptual leap. His surviving work exemplifies the application of rigorous geometry to astronomy, establishing a standard methodology for later Greek science.