When viewing the planets, Mars appears to move backwards, or retrograde, because___________ .
A) it is rotating around the Sun slower than Earth's rotation
B) it is rotating at approximately the same speed but its orbit is more elliptical than Earth's rotation
C) it is rotating at approximately the same speed but its orbit is more circular than Earth's orbit
D) it is rotating around the Sun faster than Earth's rotation

Question

Quizplus · Accepted Answer

Mars appears to move backwards, or retrograde, because it is rotating around the Sun slower than Earth's rotation. This difference in orbital speed means that from Earth's perspective, Mars seems to move backward in its orbit for a period of time as Earth passes it in its orbit around the Sun.

When Viewing the Planets, Mars Appears to Move Backwards, or Retrograde