Pretty super, if you’re in to statistics. Not so super if you’re expecting a dramatic celestial event.
The Moon orbits the Earth in an ellipse.
So twice a month, every month, it is relatively close to the Earth – between 356,400 and 370,400 kilometers away. We call that Perigee. And twice a month, every month, it is relatively far from the Earth – between 404,000 and 406,700 kilometers away. We call that Apogee.
Once in a while, the full Moon happens during apogee and appears slightly smaller than usual. Sometimes, the full Moon happens during perigee and appears slightly larger than usual. This gets named a Supermoon. The difference between how the full Moon appears at apogee and how it appears at perigee is about 14%.
On Monday, November 14th, the Moon will be at perigee and it will also be a full Moon. There’s an unusual amount of hype about it this year because the Moon, due to its orbit, is even closer than normal – closer, in fact, than it’s been since 1948 and closer than it will be again until 2034.
How much closer? About 0.02% or “a few dozen kilometers” according to Sky and Telescope Magazine. Will you be able to discern any difference at all? No, say astronomers.
The difference in apparent size of the full Moon based on your location on Earth compared to its position in the sky is significant and noticeable. When the Moon is rising or setting, it appears about 1% bigger than when it is overhead due to an increase in distance from where you’re standing by several thousand kilometers.
So if you want to observe the Supermoon and want it to be a special occasion, be sure to view it at Moonrise which occurs at 5:14 pm. The Supermoon will also appear very large at Moonset which occurs at 6:26 am.
Either way, take a selfie and post it here!