Retrograde motion (east to west among the stars) is observed
A)for some planets as Earth passes between that planet and the Sun.
B)for the Sun during the entire year.
C)for Earth's Moon during an entire month.
D)None of the other choices are correct.

Question

Quizplus · Accepted Answer

Retrograde motion is observed when Earth passes between a planet and the Sun, causing the planet to appear to move backwards (east to west) against the background stars. This is because of the difference in orbital speeds between Earth and the other planet, causing the apparent motion to appear to reverse during certain parts of the year. Retrograde motion is not observed for the Sun or Earth's Moon.

Retrograde Motion (East to West Among the Stars) Is Observed