What causes the apparent retrograde motion of the planets?
A)As Earth passes another planet,its gravitational pull slows down the other planet so that it appears to be traveling backward.
B)When planets are farther from the Sun,they move slower than when they are nearer the Sun;it is during this slower period that they appear to move backwards.
C)The other planets never really appear to move backward;the background stars shift due to Earth's revolution around the Sun.
D)As Earth passes another planet,the other planet appears to move backward with respect to the background stars,but the planet's motion does not actually change.
E)Apparent retrograde motion is an illusion created by turbulence in Earth's atmosphere.

Question

Quizplus · Accepted Answer

The apparent retrograde motion of the planets is an optical illusion that occurs when Earth, moving faster on its inner orbit, passes another planet. As Earth overtakes the slower-moving outer planet, the outer planet appears to move backward against the background stars from our perspective, although its actual motion does not change.

What Causes the Apparent Retrograde Motion of the Planets