Retrograde Motion Of Planets. When does the retrograde motion start for a planet like mars and how long (time limit) planets will appear to be in such motion? 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.
This application simulates the apparent retrograde movement that the planets perform at certain times of the year, considering, naturally, the point of view of observation from. Why do planets occasionally move backward in the night sky?