If an observer were observing Earth's motion from another planet, would they observe occasional retrograde motion?
A) no
B) yes, but only from the inner planets: Mercury and Venus
C) yes, but only from the outer planets: Mars and beyond
D) yes, from any of the planets

Question

Quizplus · Accepted Answer

Retrograde motion is observed when a planet appears to move backward in the sky relative to the stars. This is a result of the relative positions and motions of the planets as they orbit the Sun. An observer on any planet would see Earth exhibit retrograde motion at certain points in its orbit, due to the differing speeds and positions of Earth and the observing planet around the Sun.

If an Observer Were Observing Earth's Motion from Another Planet