Supermoon
Supermoon
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Supermoon

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Supermoon

A supermoon is a full moon or a new moon that nearly coincides with perigee—the closest that the Moon comes to the Earth in its orbit—resulting in a slightly larger-than-usual apparent size of the lunar disk as viewed from Earth. The technical name is a perigee syzygy (of the Earth–Moon–Sun system) or a full (or new) Moon around perigee. Because the term supermoon is astrological in origin, it has no precise astronomical definition.[contradictory]

The association of the Moon with both oceanic and crustal tides has led to claims that the supermoon phenomenon may be associated with increased risk of events like earthquakes and volcanic eruptions, but no such link has been found.

The opposite phenomenon, an apogee syzygy or a full (or new) Moon around apogee, has been called a micromoon.

The name supermoon was coined by astrologer Richard Nolle in 1979, in Dell Horoscope magazine arbitrarily defined as:

... a new or full moon which occurs with the Moon at or near (within 90% of) its closest approach to Earth in a given orbit (perigee). In short, Earth, Moon and Sun are all in a line, with Moon in its nearest approach to Earth.

— Richard Nolle

He came up with the name while reading Strategic Role Of Perigean Spring Tides in Nautical History and Coastal Flooding published in 1976 by Fergus Wood, a hydrologist with NOAA. Nolle explained in 2011 that he based calculations on 90% of the difference in lunar apsis extremes for the solar year. In other words, a full or new moon is considered a supermoon if where is the lunar distance at syzygy, is the lunar distance at the greatest apogee of the year, and is the lunar distance at the smallest perigee of the year.

In practice, there is no official or even consistent definition of how near perigee the full Moon must occur to receive the supermoon label, and new moons rarely receive a supermoon label. Different sources give different definitions.

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