During the time that a planet is in its period of apparent retrograde motion: ________.
A) The planet moves backwards (clockwise as viewed from above Earth's north pole) in its orbit of the Sun.
B) The planet appears to rise in the west and set in the east, rather than the usual rising in the east and setting in the west.
C) Over many days or weeks, the planet moves westward relative to the stars, rather than the usual eastward relative to the stars.
D) The planet is getting closer to the Sun in its orbit.

Question

Quizplus · Accepted Answer

During the time that a planet is in its period of apparent retrograde motion, it moves westward relative to the stars, rather than the usual eastward direction. This is because of the combined motion of Earth and the planet in their respective orbits. The planet is not actually moving backwards in its orbit around the Sun, but it appears to do so from our perspective on Earth. The planet also does not change its rising and setting direction. The planet's distance from the Sun does not necessarily change during this period.

During the Time That a Planet Is in Its Period