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Ptolemy

Ptolemy was a Greek astronomer who lived between 85-165 A.D. He put together his own ideas, those of Aristotle, and Hipparchus' system of epicycles and eccentric circles, to formulate the geocentric theory. Ptolemy believed that the Earth was at the center of the universe and all other heavenly bodies circled it. This Ptolemaic System was accepted for the next 1,500 years until Copernicus' heliocentric theory.

Ptolemy is also famous for his work in geography. He was the first person to use longitude and latitude lines to identify places on the face of the Earth, and developed three methods for projections in mapmaking.


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