If an observer on Earth sees the Moon to be full, then at the same time an observer on the Moon would see Earth to be at what phase?

Question

Quizplus · Accepted Answer

When the Moon appears full from Earth, it is because the Sun is directly illuminating the entire face of the Moon visible from Earth. At the same time, an observer on the Moon would see the Earth in the opposite direction of the Sun, and therefore the Earth would appear to be at a new phase (completely dark).

If an Observer on Earth Sees the Moon to Be