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views updated May 17 2018 Ptolemaic system the theory (see Ptolemy2) that the earth is the stationary centre of the universe, with the planets moving in epicyclic orbits within surrounding concentric spheres. Although heliocentric models of planetary motion had been proposed before Ptolemy, his geocentric model was so accurate in predicting the positions of the planets that it became the standard model until challenged by Copernicus. A heliocentric system was not generally accepted until the German astronomer Johannes Kepler (1571–1630) developed his laws of planetary motion, and the Ptolemaic system was only finally disproved following Galileo's observations of the phases of the planet Venus. Ptolemaic systemoxford views updated May 14 2018 Ptol·e·ma·ic sys·tem (also Ptolemaic theory) • n. hist. Astron. the theory that the earth is the stationary center of the universe, with the planets moving in epicyclic orbits within surrounding concentric spheres. Compare with Copernican system. The Oxford Pocket Dictionary of Current English
Ptolemaic system Ptolemaic systemn. The astronomical system of Ptolemy, in which the earth is at the center of the universe with the sun, moon, planets, and stars revolving about it in circular orbits at increasing distance. Some of the orbits have epicycles. American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved. Ptolemaic systemn (Astronomy) the theory of planetary motion developed by Ptolemy from the hypotheses of earlier philosophers, stating that the earth lay at the centre of the universe with the sun, the moon, and the known planets revolving around it in complicated orbits. Beyond the largest of these orbits lay a sphere of fixed stars. See also epicycle1 Compare Copernican system Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014 Ptolema′ic sys`temn. Ptolemy's conception of the universe, with the earth as the fixed center and the heavenly bodies moving about it. Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.  Ptolemaic system Ptolemy believed that Earth was at the center of the universe and that the sun and planets orbited Earth (with the planets also moving in smaller circles called epicycles). In this system, the centers of Mercury's and Venus's epicycles always lie on the line shown in the diagram between Earth and the sun. Ptol·e·ma·ic system(tŏl′ə-mā′ĭk)The astronomical system of Ptolemy, in which Earth is at the center of the universe and all celestial bodies revolve around it. The sun, moon, and planets revolve at different levels in circular orbits, and the stars lie in fixed locations on a sphere that revolves beyond these orbits. The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Definitionsfrom The American Heritage® Dictionary of the English Language, 5th Edition.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
Etymologiesfrom Wiktionary, Creative Commons Attribution/Share-Alike LicenseFrom Ptolemy ("a surname") + -ic + system. After Greek-Roman astronomer Claudius Ptolemy (c. 90 - c. 168 AD), who explained the theory in an influential work. SupportHelp support Wordnik (and make this page ad-free) by adopting the word Ptolemaic system. ExamplesSorry, no example sentences found. What do we mean by the Ptolemaic model?In order to explain the motion of the planets, Ptolemy combined eccentricity with an epicyclic model. In the Ptolemaic system each planet revolves uniformly along a circular path (epicycle), the centre of which revolves around Earth along a larger circular path (deferent).
What was Ptolemy main theory?Based on observations he made with his naked eye, Ptolemy saw the Universe as a set of nested, transparent spheres, with Earth in the center. He posited that the Moon, Mercury, Venus, and the Sun all revolved around Earth.
What is the Ptolemaic system in world history?The Ptolemaic system had the Earth at the center of the universe with the Moon, Sun, and planets orbiting the Earth in circular orbits. Only five planets, not counting the Earth, were known to the ancient Greeks and they were believed to orbit the Earth in a special motion known as epicycles.
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What is the meaning of Ptolemaic model?
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