Retrograde Motion Of Planets Explained. The apparent retrograde motion of planets (and other objects) on the sky is an illusion caused by the fact that objects in our solar system orbit the sun at different. As a planet moves around on its epicycle, the center of the epicycle (called the “deferent'') moves around the earth.
How to concisely explain apparent retrograde motions of planets? With a total solar eclipse and a mercury retrograde on the horizon,.