If we observe one edge of a planet to be redshifted and the opposite edge to be blueshifted, what can we conclude about the planet?
A) The planet is actually two bodies, one moving toward us, the other away from us.
B) The planet is in the process of falling apart.
C) The planet is in the process of formation.
D) The planet is rotating.

Question

Quizplus · Accepted Answer

The redshift and blueshift indicate that the planet is rotating, causing one edge to be moving away from us (blueshifted) and the opposite edge to be moving towards us (redshifted). This is known as the Doppler effect. Choices A, B, and C are not supported by the given observation.

If We Observe One Edge of a Planet to Be