And why do we only see one or two a year?
Supermoons can appear to be up to 14% times larger and 30% brighter than your average moon. The moon will be closest to the earth in the first hours of the next morning, although it will be a little less full. The supermoon will rise on Sunday, 3 December and will become full at 3:47pm GMT - remaining bright and full throughout the night.
North America is due to see its first and only supermoon of 2017, which is what happens when a full moon coincides with at least 90 percent of its closest approach to Earth.
The moon's average distance from the Earth is approximately 238,000 miles.
Part of it depends on where you're viewing the supermoon.
Unlike the total solar eclipse, there are no risks of going blind if you stare directly into the moonlight, which is technically a reflection of the sun's light. At that point, the moon will be just 222,135 miles from Earth, almost 16,000 miles closer than it normally is throughout the year.
The moon will be completely full on Sunday, December 3 at 3:45 a.m. EST, but will look full for a day before and after.
How to watch the only visible “supermoon” of 2017 this weekend
What time is the supermoon?
The best time to enjoy the supermoon is right after moonrise and before sunrise, when the moon is sitting on the horizon.
It can be tough to snap a good shot of the moon, but equipment like a telephoto lens or an adaptor on a small telescope helps, Faherty said.
Now there will always be the writers who, dripping with too-cool-for-school ennui, will say, "oh look, a full moon" as they explain that it's not a big deal and that the media is just setting people up for disappointment. The full moon won't come that close again until 2034.
What's the best way to photograph the supermoon?
This supermoon won't be quite as special as last year's.
To get an original shot, Ingalls suggests taking a picture that puts the moon in context of a local landmark, something that gives your photo a sense of place.