When the planet Mars is moving in a retrograde direction, its motion against the background stars is seen to be
A) stationary, with no motion against the stars.
B) exactly perpendicular to the equator.
C) eastward.
D) westward.

Question

Quizplus · Accepted Answer

When Mars is observed to be moving in a retrograde direction, it appears to move westward against the background stars, contrary to the usual eastward motion observed for most planets due to the Earth's faster orbit around the Sun.

When the Planet Mars Is Moving in a Retrograde Direction