Phases of the Moon

Full Moon Phase

During the full moon phase, the entire sunlit side of the moon faces Earth; hence, the moon is completely illuminated as viewed from Earth. Full moon occurs when the moon is on the opposite side of Earth from the sun. This means that the side of the moon facing the Earth is almost fully lighted by the sun, thus appearing round. The other hemisphere, on the other hand, is not illuminated.

As the moon revolves around Earth, you can see more of the lighted side every day, until it is fully lit. As the moon continues on its path, you see less and less of the lighted side. About 29.5 days after the last new moon, the cycle is complete, and a new moon occurs again. The full cycle of the phase change that the moon makes is the basis of the length of one month.