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The Bettmann Archive

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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Aristotle

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Galileo Galilei

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Archimedes

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Democritus

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA