c.325 ? - 255 ? BC
Aristarchus was the first astronomer to maintain that the Earth rotates - more than two thousand years before Copernicus.
Aristarchus of Samos hypothesized that the earth is not the
center of the universe, but revolves yearly about the sun and
daily rotates about its own axis.
Aristarchus also wrote a book about the distances and sizes of the moon and sun which he underestimated greatly.
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From the University of St. Andrews, Scotland
School of Mathematics