It’s a moon so big it will cover two nights.
It’s a super moon to end all super moons, and it is happening on Sunday November 13 and Monday November 14.
The moon technically turns full this month on November 14, with the moment of exact fullness happening at 8:52 a.m. EST. About two hours before that—at 6:22 a.m., according to NASA—the moon makes its closest approach to Earth for the year.
The result? A moon that appears 14 percent larger than the year’s smallest full moon, and is about 30 percent brighter.
“Because it's so close to Earth, a super full moon looks about seven percent bigger than an average full moon. When compared to a micro moon, it looks about 12 percent to 14 percent larger,” says Timeanddate.com. “A super full moon also looks about 30 percent brighter than a micro full moon and about 16 percent brighter than an average full moon.”
Why? The moon is coming full within a couple of hours of its closest approach, known as perigee, in decades. January 26, 1948, was the last time the moon edged this close, and it won’t do so again until November 25, 2034. The 1948 full moon was a negligible bit closer than this one, an approximately 30-mile difference, says Astronomy.
The distance between Earth and its moon is measured from the center of each heavenly body, and that distance drops to 221,524 miles at 6:22 a.m. on November 14. At its farthest, on Halloween this year, it was 252,688 miles away, a 30,000-mile difference, Earthsky.org notes.
The reason the moon’s distance from the Earth varies is that the moon’s orbit is an ellipse rather than a circle. In dancing around our planet, the moon usually approaches no closer than 225,800 miles at perigee and 252,000 at apogee, the farthest from Earth, according to Sky and Telescope.
“The closer perigee and the moment of full Moon are to coinciding, the more exceptional the supermoon,” says Sky and Telescope, adding that the sun’s pull also exerts an influence on the moon’s orbit. “Not only will November's full Moon occur at the closest perigee of the year, but the ‘stretchiness’ of the lunar orbit will also bring it in even closer.”
The moon’s proximity means its gravitational pull is more pronounced, which will exacerbate the tides, Earthsky.org points out. This effect will manifest a day or two afterward, and could influence the seas’ rise and fall for a good week or two afterward, says Space.com. These are called spring tides.
“This month the moon is 14 percent closer at perigee than at apogee, and so it exerts 48 percent more tidal force during the spring tides of November 14 than during the spring tides near apogee two weeks before and after,” Space.com says.
This is actually the second in a triad of super moons. There was one in October, and there’s another one next month, to finish out the year, as explained in this NASA video.
Because of the timing of fullness, the moon will appear full on both Sunday and Monday nights—though the exact moment of fullness technically falls right between the two.
East Coast observers will not end up seeing an exact full moon on either night, but the West Coast of Turtle Island will be treated to the sight in a darker sky.
“Those living in the western half of the U.S., including Alaska and Hawaii, will get to experience both the ‘special moment’ and the moon at maximum fullness in either a twilight or dark sky,” says Sky and Telescope.
"If you live in the western half of the United States or Canada, you'll be able to see the moon at full phase just before it sets that morning,” elaborates Space.com. “But elsewhere it turns full after it has set.”
As with all full moons, the main difference will be seen at the horizon, when the orb looms large in relation to what’s on the ground. Once it’s airborne, however, it may be virtually indistinguishable from any other full moon, unless one has a keen eye, a telescope or a previous photo to compare it to, Astronomy says, since it will only look seven percent larger than normal.
“And it will appear nearly 15 percent brighter than a typical full moon,” Astronomy says. “Yet these differences are barely noticeable to the naked eye under the best conditions, and even harder to discern when you try to compare the moon’s appearance across several months.”
Although the best sight will be just before dawn on Monday morning, there’s no need to set the alarm any earlier than you normally would.
“I’ve been telling people to go out at night on either Sunday or Monday night to see the supermoon,” said Noah Petro, deputy project scientist for NASA’s Lunar Reconnaissance Orbiter (LRO) mission, in a statement from NASA. “The difference in distance from one night to the next will be very subtle, so if it’s cloudy on Sunday, go out on Monday. Any time after sunset should be fine. Since the moon is full, it’ll rise at nearly the same time as sunset, so I’d suggest that you head outside after sunset, or once it’s dark and the moon is a bit higher in the sky. You don’t have to stay up all night to see it, unless you really want to!”
Spotting the moon itself is, of course, a no-brainer. In fact, the moon might do it for you, if recent studies are any indication.
But there are ways to position oneself for maximum effect. The moon will rise at 4:28 p.m. EST on Sunday November 13, and at 5:14 p.m. EST on Monday November 14, according to Timeanddate.com.
“Fortunately, the moon is very easy to spot in the sky,” notes Space.com drily. “The full moon is also in the sky all night at most locations around the world. But to see the natural satellite in all its glory on November 14, pick an area with a low enough horizon to spot the moon. Details will be enhanced in a telescope or binoculars if you find a region with low light pollution.”