Animation of the orbits of the Moon and Earth, showing the cycles that combine to produce a supermoon"". A supermoon is a full Moon that occurs when the Moon is at perigee, the closest point to Earth in its elliptical orbit, and hence appears largest in the sky. A full Moon occurs when the Moon is on the opposite side of the Earth to the Sun. This arrangement is shown at the start. The Moon orbits Earth once every 27.32 days, with respect to the stars. This is called a sidereal month. The Moon's elliptical orbit itself rotates slowly around the Earth, so the Moon does not reach its perigee point for another 0.22 days. The perigee-to-perigee period is called the anomalistic month. Due to the Earth's orbit around the Sun, the Moon takes a further 1.98 days to reach full again. The 29.53-day full-to-full cycle of lunar phases is called the synodic month. After one more synodic month the full Moon is no longer at perigee, and it is further still at the next full Moon. After 14 full Moons, the perigee is once again on the other side of the Earth from the Sun, and the full Moon is a supermoon again. This is known as the full Moon cycle, and it takes roughly 412 days, which is 14 synodic months and 15 anomalistic months."