The shape of the moon as viewed from Earth changes throughout the month as the moon orbits around the Earth. The different shapes of the moon are called lunar phases. The main lunar phases are:

* New Moon: During this phase, the moon is not visible from Earth because it is positioned between the Earth and the Sun.

* Waxing Crescent: The moon appears as a thin crescent in the sky, and the illuminated portion gradually increases.

* First Quarter (also known as Waxing Gibbous): Half of the moon is illuminated and visible from Earth.

* Full Moon: The entire moon is illuminated and visible from Earth.

* Waning Gibbous: The illuminated portion of the moon gradually decreases.

* Third Quarter (also known as Waning Crescent): Half of the moon is illuminated and visible from Earth.

* New Moon: The moon completes its orbit and returns to the New Moon phase.

The cycle of lunar phases repeats itself every 29.5 days.