And why do we only see one or two a year?
As such, it will appear 7 percent bigger and 16 percent brighter than the average full moon.
The moon's orbit around the Earth is not a flawless circle, meaning the distance between the two bodies grows and shrinks as the lunar planet plods eternal laps around us. But since the date didn't coincide with a full moon, it didn't qualify as a supermoon.
Supermoons occur when a full moon happens during perigee, the point in its orbit when it's closest to Earth - the result can make the moon appear up to 14 percent larger and 30 percent brighter than other full moons.
It's been a year since the visible supermoon last graced our skies, when the full moon was closest to the Earth.
The moon's average distance from the Earth is approximately 238,000 miles.
When can I see the supermoon?
Most astronomers suggest watching the supermoon right after sunset and into moonrise, and minutes before the next sunrise as well. The full moon won't come that close again until 2034.
According to an NPR interview with University of Arizona professor Gurtina Besla, the moon will be completely full at 12:45 a.m. on Monday, Dec. 4.
Also, look for the supermoon when it's near the horizon during moonrise/moonset. However, the moon will still appear plenty big when it rises in the eastern sky Sunday evening. If the moon is a bit bigger and brighter, even better. This is also why both times are the best for watching the supermoon.
Bill Ingalls, a NASA photographer, says that those capturing the event through their smartphones have to focus on the correct light balance.
To take a picture of the supermoon with a smartphone, tap on the moon on the screen and hold your finger in place to lock the camera's focus. Especially if you get something in the foreground when taking photos.