Models of Observed Retrograde Motions of the Planets, as Seen From Earth

The animation illustrates the account of observed retrograde motion of planets in Ptolemy’s geocentric model.

This animation illustrates the account of observed retrograde motion of planets in a heliocentric model.

This animation illustrates the heliocentric model, and, in addition, at the bottom you can see how the retrograde motion of Mars would have looked to observers of the heavens (you need to click on "AutoRun" to animate the model).