Full Moon

The point in the Moon's orbit where it lies diametrically opposite the Sun in the sky, from the perspective of an Earth-bound observer. At this point, under normal circumstances, the Moon's face is fully illuminated with sunlight. As at all other times, the hemisphere of the Moon angled away from the Sun is still cast in dark shadow, but because of the relative positions of Moon, Earth and Sun, this shadow is hidden for a while from observers on Earth.

Because the Earth passes between the Sun and the Moon at the time of Full Moon, it can, and often does, affect the Moon's visibility. This occurs when the Earth actually blocks sunlight from reaching the Moon's surface, resulting in an event known as a Lunar Eclipse, in which the Earth's circular shadow can be seen to move across the face of the Moon. Because of the orbital arrangements involved, a Lunar Eclipse can only ever occur at Full Moon.