A "supermoon"rises over the Dolomiti mountains in Levico Terme, north of Italy in 2014. (AFP/Getty Images)
There’s a rare supermoon coming this weekend, and no matter how devastated or thrilled you are by the latest election results, you don’t want to miss it.
In the wee hours of Sunday night and Monday morning, the moon will come closer to the Earth than it has in nearly 70 years.
That means those of us who remember to look up will get to see the biggest, brightest lunar disk since January 1948.
The distance between the Earth and moon is in constant flux because of the moon’s elliptical orbit. On average our planet’s only natural satellite is 238,900 miles away.
However, at exactly 3:23 a.m. PST Monday, the moon will be just 216,487 miles from the surface of the Earth — more than 20,000 miles closer than usual. It won’t be that close again until November 2034.
Astronomers emphasize that the difference in the moon’s size and brightness may not be noticeable to most sky watchers, and unless you are a die-hard moon obsessive, no reason to get out of bed in the middle of the night..
“I encourage people to go out and take a look, but I wouldn’t wake the kids up at 3 a.m.,” said Jim Lattis, director of Space Place, the University of Wisconsin-Madison’s astronomy outreach center.
Sky & Telescope senior editor Alan MacRobert noted that at its closest, the moon will appear 7% larger and 15% greater in area than average. Because the planet is closest to the sun during the months of November through January, the lunar disk will also appear 16% brighter than an average full moon.
“That’s not enough to notice unless you’re a very careful moon watcher,” MacRobert said in a statement.
“Supermoon” is a nontechnical term for a moon that turns full just as it reaches perigee — the point in its orbit when it is closest to Earth.
The phrase was coined by an astrologer — not an astronomer — in 1979. Scientists prefer the term “perigean full moon” or “perigee-syzygy.”
This celestial phenomenon occurs about once every 14 full moons, but because of a variety of factors, most supermoons rarely occur at such a short distance from the Earth.
Among the reasons this moon will be so close to the planet is that the moon’s orbital extremes are greatest when the Earth is closest to the sun.