- a system elaborated by Ptolemy and subsequently modified by others, according to which the earth was the fixed center of the universe, with the heavenly bodies moving about it.
Origin of Ptolemaic system
First recorded in 1765–75
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- 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 starsSee also epicycle (def. 1) Compare Copernican system
- 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. See more at epicycle.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.