In the heliocentric model,retrograde motion occurs when:
A) a planet travels along an epicycle in the opposite sense of its usual orbit.
B) Earth is moving along its orbit on the opposite side of the Sun from another planet.
C) a planet's velocity changes as it moves nearer to or farther from the Sun.
D) Earth catches and passes another planet in its orbit.

Question

Quizplus · Accepted Answer

Retrograde motion in the heliocentric model is observed when Earth, moving faster in its orbit, overtakes and passes another planet. This relative motion makes the other planet appear to move backward (retrograde) against the background stars from our perspective on Earth.

In the Heliocentric Model,retrograde Motion Occurs When