Retrograde Motion Definition

Retrograde Motion Definition. Want to know what causes the apparent retrograde motion of the planets? “retrograde” is derived from the latin words retro, backwards, and gradus, step.

Retrograde motion, in astronomy, real or apparent movement of a planet, dwarf planet, moon, asteroid, or comet from east to west relative to the fixed stars. 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.