Phases of the Moon

Changes in the Moon's visible shape

A New Moon. is when the Moon is completely dark; a Full Moon is when we see all of it's bright side. The Moon is said to be waxing as it grows from a New to a Full Moon over two weeks, and waning as it shrinks back to a New Moon over the next two weeks. A waxing or waning Moon seems to bulge on the side nearest the sun, so it is often called gibbous.

Lunar month

The time it takes for the Moon to go through all the phases

It takes the Moon 27,3 days to circle the Earth, but it takes 29.53 days to go from one Full Moon to the next, because the Earth moves as well as the Moon. A cycle of 29.53 days is a lunar month.