Aristarchus of Samos

Greek astronomer and mathematician (c.310-c.230 BC) · Scientists · Lived 310 BC to 230 BC · aged 80

Aristarchus of Samos is read about 506 times a day, in 71 languages.

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He put the Sun at the center eighteen centuries before Copernicus did. The idea didn't take - Aristotle's Earth-centric cosmos won the argument for the next two thousand years - but Aristarchus had already worked it out: Earth orbiting, rotating, smaller than the star it circles.

Scientists Scientist Astronomy Ancient History

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(S. Clerestory 1) Science Window

Aristarc

Aristarchos

Aristarchus Commandino 1572

Aristarchus Diebolt Merley cour Carree Louvre

Aristarchus van Samos, atlas of Cellarius (1646)

Aristarchus working

Aristarchus-Moon-Earth-Sun

In their own words 10

Aristarchus of Samos

10 statements, newest first

[Hypotheses]1. That the Moon receives its light from the sun.2. That the earth is in the relation of a point and centre to the sphere in which the moon moves.3.
Note: "is less than a quadrant..." is less than 90° by l/30th of 90° or 3°, and is therefore equal to 87°, i.e., Aristarchus assumes that, Own words
We are now in a position to prove the following propositions : - 1.
Tr. & Notes by Sir Thomas Heath, as contained in Aristarchus of Samos, the Ancient Copernicus (1913), Own words
Proposition 2. If a sphere be illuminated by a sphere greater than itself, the illuminated portion of the former sphere will be greater than a hemisphere.
Tr. & Notes by Sir Thomas Heath, as contained in Aristarchus of Samos, the Ancient Copernicus (1913), Own words

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About this person

Born in Samos around 310 BC, Aristarchus likely studied in Alexandria under Strato of Lampsacus. He built sundials, observed the summer solstice of 280 BC, and attempted to measure the sizes and distances of the Sun and Moon. His calculation that the Sun was seven times larger than Earth (wildly low, but still enormous by ancient standards) led him to a radical conclusion: something that massive belonged at the center. He took Philolaus's old idea of a central fire and recast it as the Sun, arranging the planets in their correct order around it and suspecting the stars were distant suns. The model was rejected. Aristotle and Ptolemy's geocentric universe held the floor until Copernicus, who knew Aristarchus had proposed a moving Earth but likely never grasped that he'd already solved the whole puzzle.