In Ptolemy's theory, retrograde planetary motion is explained as
A) a result of Earth's motion: as Earth passes another planet, that planet appears to move backward as seen against the background stars.
B) due to the natural wandering of the celestial sphere of background stars.
C) the backward part of the planet's loop- the- loop orbits around Earth.
D) due to the back- and- forth or "oscillatory" motion that planets make as they move along their circular orbits around Earth.
E) Actually he didn't have an explanation for this.

Question

Quizplus · Accepted Answer

Ptolemy explained retrograde motion using the concept of epicycles, where planets move in small circles (epicycles) while simultaneously orbiting Earth in larger circles (deferents), creating a loop-the-loop effect.

In Ptolemy's Theory, Retrograde Planetary Motion Is Explained as