A planet appears to move briefly westwards as Earth overtakes it. This is called:
ARetrograde motion
BPrecession motion
CRectilinear motion
DReciprocal motion
Answer & Solution
Correct answer: A. Retrograde motion
1. Normally planets drift eastwards among the stars.
2. As Earth passes one, it seems to back up for a while.
3. That temporary reversal is retrograde motion.
_Source: OpenStax Astronomy 2e, Chapter 2, Observing the Sky: The Birth of Astronomy._
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