Who was Aristarchus of Samos? - Greek Astronomy - Heliocentrism
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Who was Aristarchus?

Aristarchus manuscript
A copy of Aristarchus' work on parchment from
Constantinople, about 950 AD, showing the
relative sizes of the sun, the Earth, and the moon

Aristarchus, who was born on the Greek island of Samos around 310 BC, spent most of his life working at the University of Alexandria in Egypt. Aristarchus is the first person we know of who suggested that the earth might go around the sun and not the other way around.

Aristarchus figured out that the earth went around the sun 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. It wasn't until more than a thousand years later that Al-Ghazali and other Islamic astronomers took Aristarchus (arr-iss-TAR-kuss) 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 also realized for the first time that the stars must be very far away, much farther than the sun or the moon, but again, he couldn't prove it without a good telescope.

Learn by doing: the earth-sun-moon dance
More Greek ideas about the Earth and the Sun

Bibliography and further reading about Aristarchus:

Greek and Roman Science, by Don Nardo (1998). Nardo has written a lot of good books about the ancient world for kids; this one is no exception.

Ancient Science: 40 Time-Traveling, World-Exploring, History-Making Activities , by Jim Wiese (2003). Activities, as the title says - how to make your own sundial, and so on. The author is a science teacher.

Early Greek Science: Thales to Aristotle, by Geoffrey Lloyd (1974).

History of Greek Mathematics: From Aristarchus to Diophantus, by Thomas L. Heath (1921, reprinted 1981). A lot of Euclid, but also describes who the other major Greek mathematicians were and what they did.

Episodes from the Early History of Mathematics, by Asger Aaboe (1997).

More about Archimedes
Ancient Greece
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Professor Carr

Karen Eva Carr, PhD.
Assoc. Professor Emerita, History
Portland State University

Professor Carr holds a B.A. with high honors from Cornell University in classics and archaeology, and her M.A. and PhD. from the University of Michigan in Classical Art and Archaeology. She has excavated in Scotland, Cyprus, Greece, Israel, and Tunisia, and she has been teaching history to university students for a very long time.

Professor Carr's PSU page

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