Which Greek astronomer proposed that the Earth orbits the Sun — eighteen centuries before Copernicus?
Aristarchus's original treatise on heliocentrism is lost; the proposal survives only through a single passage in Archimedes' *Sand-Reckoner*. The Greek astronomical mainstream — Hipparchus and Ptolemy — rejected it because no stellar parallax was observable (it would not be measured until Bessel in 1838). The Stoic philosopher Cleanthes argued Aristarchus should be prosecuted for impiety. Copernicus revived the model in 1543 and cited Aristarchus by name in his preface.
Read the full story →Aristarchus of Samos proposed around 270 BC that the Earth orbits the Sun, not the other way around. The classical and late-antique Greek astronomical mainstream — including Hipparchus and Ptolemy — rejected the proposal on empirical grounds. The work survives only through a single passage in Archimedes.
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