Why does the Moon shine?
The Moon is by far the brightest object in the night sky, but it has no light of its own. Moonlight is simply the reflected light of the Sun. Parts of the Moon that are not in sunlight are invisible against the deep blackness of space. Although the Moon appears bright and silvery, only a small proportion of the light that falls on it from the Sun is reflected back towards us. This is because the Moon’s surface is grey and rocky, and does not reflect light well.
Why does the Moon seem to change shape each month?
The appearance of the Moon alters, depending on the position of the Sun in relation to the Moon. The Sun lights up only one side of the Moon. As the Moon orbits the Earth, we see this lit-up area from different angles. When the Sun is almost behind the Earth, it lights up the whole of the Moon; this is called a Full Moon. When the Sun is off to one side, part of the Moon is in deep shadow and all we can see is a thin slice, or crescent, of the Moon’s lit surface.