The moon reflects its light from the sun, only the part of the moon that faces the sun is visible. As the moon revolves around the Earth, its shadow covers part of its surface. The full moon is when the entire moon is visible. A quarter way through the cycle, half of the moon is visible, known as the first quarter. Half way through the month, the moon seems to disappear, which is known as a new moon. Another quarter way through the cycle, the other half of the moon is visible; this is known as the third quarter.
