A supermoon is a new or full moon that happens to coincide with a close approach of the moon to the earth. Saturday’s full moon will be the closest it has been to Earth in 18 years, according to Spaceweather.com.
The distance between the Earth and the moon during the event will be about 221,567 miles, as compared to the average distance of 238,000 miles, according to Space.com.
That may not seem like much of a difference (and compared to the distance it’s not), but the diameter of the moon is only 2,159 miles. That means the moon will be over 7.5 diameters closer to Earth than average.
The supermoon is also often linked to astrological changes. Lynn Hayes of beliefnet detailed some of those potential changes here, though also ties the moon to Earth’s motions and many theories that have been challenged by NASA.