A simple illustration showing the basic elements of Ptolemaic astronomy. It shows a planet rotating on an epicycle which is itself rotating around a deferent inside a crystalline sphere. The center of the system is marked with an X, and the earth is slightly off of the center. Opposite the earth is the equant point, which is what the planetary deferent would actually rotate around. Distances have been exaggerated as has the simplicity for the purposes of illustration.

Created by User:Fastfission in Adobe Illustrator.

Esta obra foi dedicada ao domínio público pelo autor, Fastfission, com aplicação em todo o mundo. Nalguns países isto pode não ser legalmente possível; se assim for: Fastfission concede a todos o direito de usar esta obra para qualquer fim, sem quaisquer condições, a menos que tais condições sejam impostas por lei.

If you want to credit someone, credit "Wikimedia Commons." Otherwise don't credit anyone, that's fine by me. --Fastfission 15:02, 14 April 2008 (UTC)