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# Aristarchus, Sun at center of Universe

80 years

Aristarchus of Samosis the first person we know of who suggested that the earth might go around the sun and not the other way around. He figured this out by looking at the shadow of the earth on the moon during an eclipse of the moon (now that Thales had shown how to predict eclipses and Anaxagoras had shown how eclipses worked). He used Euclid's geometric theories, and his own, to do his calculations. Most people at the time thought this was ridiculous, and instead followed Aristotle's idea that the sun went around the earth. Copernicus, at the end of the Middle Ages, almost two thousand years later, was the first person to take Aristarchus seriously. Aristarchus also used the work of Eratosthenes to figure out the size of the moon, and to calculate that the sun had to be a lot bigger than either the earth or the moon (though he didn't get the sizes right because he didn't have a good telescope).

Aristarchus of Samosis the first person we know of who suggested that the earth might go around the sun and not the other way around. He figured this out by looking at the shadow of the earth on the moon during an eclipse of the moon (now that Thales had shown how to predict eclipses and Anaxagoras had shown how eclipses worked). He used Euclid's geometric theories, and his own, to do his calculations. Most people at the time thought this was ridiculous, and instead followed Aristotle's idea that the sun went around the earth. Copernicus, at the end of the Middle Ages, almost two thousand years later, was the first person to take Aristarchus seriously. Aristarchus also used the work of Eratosthenes to figure out the size of the moon, and to calculate that the sun had to be a lot bigger than either the earth or the moon (though he didn't get the sizes right because he didn't have a good telescope). More

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# Aristarchus, Sun at center of Universe

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