<P> Apparent retrograde motion is the apparent motion of a planet in a direction opposite to that of other bodies within its system, as observed from a particular vantage point . Direct motion or prograde motion is motion in the same direction as other bodies . </P> <P> While the terms direct and prograde are equivalent in this context, the former is the traditional term in astronomy . The earliest recorded use of prograde was in the early 18th century, although the term is now less common . </P>

What is a planets backward motion in the sky called