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.
It was astrologer Richard Nolle who linked the full moon of March 19 to natural disasters. He claimed that this "supermoon" would trigger massive earthquakes, volcanoes and powerful storms when it arrived. But scientists assure that this is not the case.
[Noted NASA scientist Jim] Garvin, for example, said the moon's effects on Earth have been the subject of extensive studies.
"The effects on Earth from a supermoon are minor, and according to the most detailed studies by terrestrial seismologists and volcanologists, the combination of the moon being at its closest to Earth in its orbit, and being in its 'full moon' configuration (relative to the Earth and sun), should not affect the internal energy balance of the Earth since there are lunar tides every day," Garvin wrote.
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.