If an observer were standing on the Moon with Earth in view, how much time would elapse between two successive "Earthrises?"
A) about 1 synodic month
B) about 1 sidereal month
C) essentially forever
D) about 1 day

Question

Quizplus · Accepted Answer

From the perspective of an observer on the Moon, the Earth doesn't experience "rises" and "sets" like the Moon does from Earth. This is because the same side of the Moon always faces the Earth due to synchronous rotation. Therefore, if an observer were on the part of the Moon facing Earth, they would see the Earth essentially hanging in the same spot in the sky, not rising or setting.

If an Observer Were Standing on the Moon with Earth