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A Supermoon happens when a Full Moon or New Moon coincides with the Moon's closest approach to Earth; also called perigee.
 

Next Supermoon December 2017

The next Supermoon will be on December 3, 2017.

The Supermoon on November 14, 2016, was the closest since January 26, 1948. The next time a Full Moon will come even closer to Earth is on November 25, 2034 (dates based on UTC time).

 

Super Full Moon and Super New Moon

A Super Full Moon looks larger.

When a Full Moon coincides with its closest approach to Earth, it is called a Super Full Moon. A New Moon that takes place when the Moon is around its perigee is known as a Super New Moon.

A Micromoon, on the other hand, is when a Full or a New Moon is farthest from the Earth, around apogee. It's also known as a Minimoon, Mini Full Moon, or a Mini New Moon.