By Rod Hill on 2016-11-14
When is the Moon a Super Moon?
Originally, the term "Super Moon" was used by astronomers to describe a full Moon when it is within 90% of its closest approach to Earth, in any given orbit. The term has become popular and is now used to describe any full Moon that appears larger than usual.
Astronomers call this sort of close full moon a perigee full moon. The word perigee describes the moon’s closest point to Earth for a given month. On November 14th, the full moon will be at 5:52 a.m. PST followed by the perigee at 3:36 p.m. PST. Full moons vary in size because of the elliptical (oval) shape of the Moon's orbit. Perigee, or the Moon's closest approach Moon to Earth is about 31,068 miles closer to Earth than the its apogee or farthest distance. The Moon's distance at perigee changes by 3% over a period of 18.6 years, but in general while at perigee, a full moon would appear about 14% bigger and 30% brighter than a corresponding full moon at apogee, but it's not really all that much more dramatic than a regular full moon. On November 14th the Moon will be full, and just 221,524 miles away, making it the closest approach to Earth in 2016. According to NASA, this full moon will be not only the closest and brightest supermoon of 2016 but also the largest since 1948. What's more, the full moon won't come this close to Earth again until November 25, 2034.
(The above is courtesy of Jim Todd - director of space science with OMSI)
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