Supermoon is a term used to describe how large or how close the moon is to Earth and on Saturday, March 19, 2011, the full moon is going to be the larger than usual. The moon sometimes gets closer to Earth than at other times, this causes the moon to appear much larger.
There is a conspiracy theory brewing in that the Supermoons are related to the massive earthquakes and tsunamis. This however has not been proven. The moon is however shown to cause increased tides on a full moon because of gravitational pull.
The full moon on March 19, 2011 will be the closest it has been to Earth since 1992. When the Moon is closest to Earth it is said to be at its perigee. When it is at the farthest distance from Earth it is at its apogee.
The effects of a Supermoon can be subtle providing more light and a slightly larger size. Still, it would be worth a look outside tonight to see the Supermoon. The next time there is a Supermoon will be on November 14, 2016.