“Supermoon” is a non-technical term for a moon that turns full at the same time it hits perigee — the point on its orbit when it is closest to Earth. The moon’s path around our planet is shaped more like an oval than a circle, so there are times when it is closer to us (perigee) and times when it is farther away (apogee).
Supermoons occur about once every 14 months on average. However, Sunday night’s supermoon is extra super because the moon will be even closer to Earth than usual. At its closest approach, the moon will be 221,524 miles from our planet, compared with an average distance of 238,900 miles.
The last time the moon sailed this close to Earth was on Jan. 26, 1948, when it came 30 miles closer. The next time won’t be until Nov. 24, 2034, when the distance between the two bodies will be 40 miles less. (Los Angeles Times)