what is a super moon

A supermoon is a full moon or a new moon that nearly coincides with perigee, which is the closest point that the Moon comes to the Earth in its elliptic orbit, resulting in a slightly larger-than-usual apparent size of the lunar disk as viewed from Earth. The term "supermoon" was coined in 1979 and is often used to describe what astronomers would call a perigean full moon, which is a full moon occurring near or at the time when the Moon is at the closest point in its orbit around Earth. Supermoons are not unusual and occur as a regular part of the Moons orbit of Earth. The Moon's orbit has a slight "eccentricity," meaning it travels in an elliptical path around the Earth, so it is sometimes nearer and sometimes further away. When a full Moon occurs at the closest point to Earth during its orbit, it appears larger and brighter, becoming what is commonly known as a "supermoon". Supermoons cast about 30% more light on the planet than a full moon at its farthest distance from Earth. The term "supermoon" is used to describe a full Moon that occurs within a day or so of perigee, so they happen three to four times a year.