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.

Este trabajo ha sido liberado al dominio público por su autor, Fastfission. Esto aplica para todo el mundo. En algunos países esto puede no ser legalmente factible; si ello ocurriese: Fastfission otorga a cualquier persona el derecho de usar este trabajo para cualquier propósito, sin ningún tipo de condición, a menos que éstas sean requeridas por la ley.

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)