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astrology  A pseudoscience that holds that people and events are influencedby the configurations of the Sun, Moon, and planets with respect to each other and the stars.
deferent  One of the circles on which a planet moved according to the Ptolemaic model of the solar system.
epicycle  One of the circles upon which a planet moved according to the Ptolemaic (geocentric) model of the solar system. The center of the epicycle moved on a larger circle, called the deferent.
equant  In the Ptolemaic system, the point from which the motion of the epicycle around the deferent is uniform.
geocentric  Centered on the Earth. In a geocentric model of the solar system, the planets moved about the Earth.
precession  The slow, periodic conical motion of the rotation axis of the Earth or another rotating body.







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