Natural Phenomenon

Supermoon

A supermoon occurs when the moon’s orbit is closest (perigee) to Earth at the same time it is full.

Actually, “supermoon” isn’t new. The term first appeared in a 1979 article for Dell Horoscopemagazine. The author, American astrologer Richard Nolle, described it as “a New or Full Moon which occurs with the Moon at or near (within 90 percent of) its closest approach to Earth in a given orbit.” Nolle gave no reason for his “within 90 percent of” delimiter. Like most astrological numbers, the range gives the predictor a huge amount of wiggle room.

It’s easy to understand why a term like supermoon would catch on. It describes in general terms how one particular Full Moon each year rates, and — at least for the general public — it sure beats the astronomical term: perigee-syzygy Moon.

Perigee means “closest to Earth,” and syzygy is a term astronomers use for a lineup of three celestial bodies, in this case, the Moon, Earth, and the Sun, in that order. Note that a class of supermoons also occurs at New Moon (when the syzygy would be Earth-Moon-Sun), but because we can’t see the Moon at its New phase, 

-The Moon orbits Earth in an ellipse, an oval that brings it closer to and farther from Earth as it goes around.
-The farthest point in this ellipse is called the apogee and is about 253,000 miles (405,500 kilometers) from Earth on average.
-Its closest point is the perigee, which is an average distance of about 226,000 miles (363,300 kilometers) from Earth. 
-When a full moon appears at perigee it is slightly brighter and larger than a regular full moon—and that's where we get a "supermoon.