Why do we have different phases of the Moon?
As the Moon races around the Earth, different amounts of its Earth-facing side are lit by the Sun.
During a Full Moon, the side facing our planet directly is complexity illuminated.
But when the Moon finds itself on the other side of the planet, its backside is lit by the Sun and the Moon appears to vanish from our sky for one or two nights.
This is the New Moon phase of the lunar cycle, which lasts 29.5 days from one New Moon to the next.
At the same time, the Moon takes about 27.3 days to complete an orbit around the Earth.