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Ptolemaic System

The Earth at the Center


This is an illustration of the Ptolemaic system of astrology, created around 1660 by Andres Cellarius.
Ptolemaic System
Early astronomer-astrologers subscribed to the theory that the Earth is at the center, with planets in motion around the ecliptic. 2nd-century Hellenistic (a.k.a. Greek) astronomer Ptolemy published a comprehensive work called Almagest, with this geocentric model as the foundation. The Earth-as-center theory was challenged around the 17th-century by Copernicus and Gallileo. The geocentric model was replaced with the heliocentric model, one with the Sun at the center.

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