Question

Why moon appears in different shapes

Answer 1

We only see the Moon because sunlight reflects back to us from its surface. During the course of a month, the Moon circles once around the Earth. If we could magically look down on our solar system, we would see that the half of the Moon facing the Sun is always lit. But the lit side does not always face the Earth!

Answer 2

The Moon doesn't emit (give off) light itself, the 'moonlight' we see is actually the Sun's light reflected off the lunarsurface. So, as the Moon orbits the Earth, the Sun lights up different parts of it, making it seem as if the Moon is changing shape.