The lunar phases are the changes in the shape of the illuminated part of the Moon when viewed by an observer on Earth. These changes are cyclical according to the position of the Moon respecting the Earth and the Sun. That is to say, depending on the location of the Moon, the Earth and the Sun, a greater or lesser portion of the visible face of Moon. The phases of the Moon are produced by two causes: the movement of the Moon's rotation around the Earth and because the Moon reflects the light of the Sun as a mirror.
A lunar cycle is the span of 29.5 days during which all phases are observed. At the end of the last phase, the cycle is repeated. The 4 best known forms are the new Moon, the full Moon, the waning room and the growing room, but there are other intermediate ones. Its appearance varies from 0% illumination during the new Moon to 100% when it is a full Moon.
The moons phases depend on how much the earth blocks light between the sun and the moon. The phases depend on where the moon is in respect to the sun in space.
