This phenomenon is known as a full moon. During a full moon, the sun is directly opposite the moon, causing the entire face of the moon that is visible from Earth to be illuminated. This is in contrast to a new moon, where the moon is between the Earth and the sun, resulting in no visible illumination of the moon from Earth. The phases of the moon that occur in between a new moon and a full moon are known as waxing crescent, first quarter, waxing gibbous, waning gibbous, last quarter, and waning crescent. These phases are a result of the changing positions of the sun, Earth, and moon in relation to one another, causing varying amounts of the moon's face to be illuminated.
