From Earth we always see the same side of the Moon, which the Sun illuminates each night in different proportions, and progressively, depending on the position of the Moon with respect to the Sun and the Earth. The different ways we see the Moon illuminated from Earth They are called lunar phases and follow a cycle of 29.53 days.
The four best-known phases of the Moon are:
- Full moon or full moonwith the visible side of the Moon illuminated at 100%.
- waning moonin which the illumination has been decreasing until it covers only 50% of the visible side of the Moon.
- new moon or new moonwith the side of the Moon normally visible from Earth in complete darkness.
- crescent moonin which the illumination has increased again to cover 50% of the surface of the Moon that we see from Earth.