| 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. |
| Ptolemaic system n. 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. |
Ptolemaic system  (tŏl'ə-mā'ĭk) Pronunciation Key
(click for larger image in new window) 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. |