An apparent westward motion of a planet in the sky compared to the background stars (as viewed from Earth) when observed on successive nights is referred to as
A)epicycle.
B)retrograde motion.
C)prograde motion.
D)heliocentric motion.
E)deferent.

Question

Quizplus · Accepted Answer

The apparent westward motion of a planet in the sky compared to the background stars (as viewed from Earth) when observed on successive nights is referred to as retrograde motion. This occurs because of the difference in orbital speeds and distances between planets and Earth as they move around the Sun.

An Apparent Westward Motion of a Planet in the Sky