what does nasa say about why we have moon phases
StarChild Question of the Month for March 2002 It is all a result of the Moon's orbit around the Earth, and the Earth's orbit around the Sun. And exactly when you see the Moon in the shape of a 'U' (lit on the bottom) rather than a backward 'C' (lit on the side) depends on what latitude you are at. But the explanation is the same regardless of when you see it from your location. We see the Moon in the night sky because it is reflecting light from the Sun. The Moon does not generate any light of its own. So the lit part of the Moon always points toward the Sun.