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.

S'ha alliberat aquesta obra al domini públic pel seu autor Fastfission. Això s'aplica a tot el món. En alguns països això pot no ser legalment possible, en tal cas: Fastfission concedeix a tothom el dret d'usar aquesta obra per a qualsevol propòsit, sense cap condició llevat d'aquelles requerides per la llei.

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)