|A supermoon image of March 19, 2011|
In astrology, a supermoon is a full or new moon that coincides with a close approach by the Moon to the Earth. The Moon's distance varies each month between approximately 354,000 km (220,000 mi) and 410,000 km (254,000 mi) due to its elliptical orbit around Earth.
DefinitionThe name SuperMoon was coined by astrologer Richard Nolle in 1979, defined as:
The term supermoon is not widely accepted or used within the astronomy or scientific community, who prefer the term perigee-syzygy. Perigee is the point at which the moon is closest in its orbit to the Earth, and syzygy is full or new moon, when the Earth, the moon and the sun are aligned. Hence, supermoon can be regarded as a combination of the two, although they do not perfectly coincide each time. 
Effect on tidesThe combined effect of the Sun and Moon on the Earth's oceans, the tide, is greatest when the Moon is new or full (see Tide#Range variation: springs and neaps). At lunar perigee the tidal force is even stronger, resulting in more extreme high and low tides, but even at its most powerful this force is still weak.
Link to natural disastersSome studies have reported a weak correlation between lunar activity and shallow, very low intensity earthquakes. However, no evidence has been found of any correlation with major earthquakes.
It has been speculated that the Indian Ocean tsunami and earthquake on December 26, 2004, was influenced by a supermoon which occurred 2 weeks later on January 10, 2005. Similar speculation was made with the 2011 Tōhoku earthquake and tsunami which occured 8 days prior to the the closest supermoon since 1992. In both cases the Moon was closest to the apogee (greatest distance).  However, the three closest supermoons in the twentieth century did not coincide with any earthquakes above 6.0 MW. 
Dates of supermoons between 1950 and 2050
There are approximately four to six supermoons annually. The following is a list of past and predicted extreme supermoons.
- November 10, 1954
- November 20, 1972
- January 8, 1974
- February 26, 1975
- December 2, 1990
- January 19, 1992
- March 8, 1993
- January 10, 2005
- December 12, 2008
- January 30, 2010
- March 19, 2011
- November 14, 2016
- January 2, 2018
- January 21, 2023
- November 25, 2034
- January 13, 2036
- ^ a b c Plait, Phil. "No, the “supermoon” didn’t cause the Japanese earthquake". Discover Magazine. http://blogs.discovermagazine.com/badastronomy/2011/03/11/no-the-supermoon-didnt-cause-the-japanese-earthquake/. Retrieved 14 March 2011; published March 11, 2011.
- ^ Hawley, John. "Appearance of the Moon Size". Ask a Scientist. Newton. http://www.newton.dep.anl.gov/askasci/phy99/phy99371.htm. Retrieved 14 March 2011; no publication date.
- ^ a b c Nolle, Richard. "Supermoon". Astropro. http://www.astropro.com/features/articles/supermoon/. Retrieved 14 March 2011; no publication date; modified March 10, 2011.
- ^ Ledermann, Tug. "'Perigee-syzygy' caused full moon to look bigger, brighter in October". University Wire. http://www.highbeam.com/doc/1P1-146006378.html. Retrieved 14 March 2011; published November 13, 2007.
- ^ Plait, Phil. "Tides, the Earth, the Moon, and why our days are getting longer". Bad Astronomy. http://www.badastronomy.com/bad/misc/tides.html. Retrieved 14 March 2011; published 2008; modified March 5, 2011.
- ^ "Apogee and Perigee of the Moon". Moon Connection. http://www.moonconnection.com/apogee_perigee.phtml. Retrieved 14 March 2011; no publication date.
- ^ "Can the position of the moon affect seismicity?". The Berkeley Seismological Laboratory. http://seismo.berkeley.edu/faq/planets.html. Retrieved 14 March 2011; published 1999.
- ^ Fuis, Gary. "Can the position of the moon or the planets affect seismicity?". U.S. Geological Survey: Earthquake Hazards Program. http://earthquake.usgs.gov/learn/faq/?faqID=109. Retrieved 14 March 2011; no publication date.
- ^ Wolchover, Natalie. "Will the March 19 'Supermoon' Trigger Natural Disasters?". Life's Little Mysteries. http://www.lifeslittlemysteries.com/will-supermoon-cause-earthquake-storm-natural-disasters-1442/. Retrieved 15 March 2011; published March 9, 2011.
- ^ Paquette, Mark. "Extreme Super (Full) Moon to Cause Chaos?". Astronomy Weather Blog. AccuWeather. http://www.accuweather.com/blogs/astronomy/story/46417/extreme-super-full-moon-to-cause-chaos.asp. Retrieved 14 March 2011; published March 1, 2011.
- ^ "Is the Japanese earthquake the latest natural disaster to have been caused by a 'supermoon'?". The Daily Mail. http://www.dailymail.co.uk/sciencetech/article-1365225/Japan-earthquake-tsunami-Did-supermoon-cause-todays-natural-disaster.html. Retrieved 14 March 2011; published March 11, 2011.
- ^ Byrd, Deborah. "Debunking the "Supermoon" Theory of Japan's Earthquake and Tsunami". Fast Company. http://www.fastcompany.com/1737710/the-supermoon-and-japans-89-magnitude-earthquake. Retrieved 14 March 2011; published March 11, 2011.
- ^ Yesterday's supermoon did not cause any disasters, Asia One, 2011-03-20
- ^ Nolle, Richard. "20th Century SuperMoon Alignments". Astropro. http://www.astropro.com/features/tables/cen20ce/suprmoon.html. Retrieved 14 March 2011; no publication date.
- ^ Nolle, Richard. "21st Century SuperMoon Alignments". Astropro. http://www.astropro.com/features/tables/cen21ce/suprmoon.html. Retrieved 14 March 2011; no publication date.
- ^ Fazekas, Andrew. ""Supermoon": Biggest Full Moon in 18 Years Saturday". National Geographic. http://news.nationalgeographic.com/news/2011/03/110318-supermoon-earth-japan-earthquake-tsunami-science-space-biggest-full-moon/. Retrieved 20 March 2011; published March 17, 2011.