Whenever you look up at the moon, you always see the same side, why? A relatively simple question with a relatively simple answer, the Moon rotates on its axis in the same amount of time it takes to rotate the Earth. If we consider the Sun’s relationship into these two orbits then we can also understand the different phases of the Moon (new, first quarter, full, last quarter, and the in between phases of crescent and gibbous).

The first video demonstrates why we see the same side of the Moon, and the second covers the different phases of the Moon.

The Universe: The Phases of The Moon