"Super Moon" redirects here. For the album by Dirty Heads, seeSuper Moon (album).
A juxtaposition of the apparent diameters of a more-average full moon on December 20, 2010 (left), and of the supermoon of March 19, 2011 (right) as viewed from Earth
Asupermoon is afull moon or anew moon that nearly coincides withperigee—the closest that the Moon comes to the Earth inits orbit—resulting in a slightly larger-than-usualapparent size of the lunar disk as viewed from Earth.[1] The technical name is aperigee syzygy (of the Earth–Moon–Sun system) or afull (ornew)Moon around perigee.[a] Because the termsupermoon isastrological in origin, it has no preciseastronomical definition.[2][contradictory]
The association of the Moon with bothoceanic andcrustal tides has led to claims that the supermoon phenomenon may be associated with increased risk of events like earthquakes andvolcanic eruptions, but no such link has been found.[3]
The opposite phenomenon, anapogee syzygy or afull (ornew)Moon around apogee, has been called amicromoon.[4]
The namesupermoon was coined byastrologer Richard Nolle in 1979, inDell 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.
NASA image showing comparison of a supermoon (left) and a micromoon (right)
He came up with the name while readingStrategic Role OfPerigean Spring Tides in Nautical History andCoastal Flooding published in 1976 by Fergus Wood, ahydrologist withNOAA.[6][7] Nolle explained in 2011 that he based calculations on 90% of the difference in lunarapsis extremes for thesolar year. In other words, a full or new moon is considered a supermoon if where is thelunar distance atsyzygy, is the lunar distance at the greatestapogee of the year, and is the lunar distance at the smallestperigee of the year.[8][9]
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.[10][11]
The termperigee-syzygy orperigee full/new moon is preferred in the scientific community.[12] Perigee is the point at which the Moon is closest in its orbit to the Earth, andsyzygy is when the Earth, the Moon and the Sun are aligned, which happens at everyfull ornew moon. AstrophysicistFred Espenak uses Nolle's definition but preferring the label offull Moon at perigee, and using the apogee and perigee nearest in time rather than the greatest and least of the year.[13] Wood used the definition of a full or new moon occurring within 24 hours of perigee and also used the labelperigee-syzygy.[7]
Wood also coined the less used termproxigee where perigee and the full or new moon are separated by 10 hours or less.[7]Nolle has also added the concept ofextreme supermoon in 2000 describing the concept as any new or full moons that are at "100% or greater of the mean perigee".[14]
Of the possible 12 or 13 full (or new) moons each year, usually three or four may be classified as supermoons, as commonly defined.
The most recent full supermoon occurred on November 15, 2024, and the next one will be on October 7, 2025.[13]
The supermoon of November 14, 2016, was the closest full occurrence since January 26, 1948, and will not be surpassed until November 25, 2034.[15]
The closest full supermoon of the 21st century will occur on December 6, 2052.[16]
Supermoons will be the marked points nearest the bottom of the graph.
The oscillating nature of thedistance to the full or new moon is due to the difference between thesynodic andanomalistic months.[13] The period of this oscillation is about 14 synodic months, which is close to 15 anomalistic months. Thus every 14lunations there is a full moon nearest to perigee.
Occasionally, a supermoon coincides with atotal lunar eclipse. The most recent occurrence of this by any definition was inMay 2022, and the next occurrence will be inOctober 2032.[13]
In theIslamic calendar, the occurrence of full supermoons follows a seven-year cycle. In the first year, the full moon is near perigee in month 1 or 2, the next year in month 3 or 4, and so on. In the seventh year of the cycle the full moons are never very near to perigee. Approximately every 20 years the occurrences move to one month earlier. At present such a transition is occurring, so full supermoons occur twice in succession. For example inHijri year 1446, they occur both in month 3 (Rabīʿ al-ʾAwwal, on September 18, 2024) and in month 4 (Rabīʿ ath-Thānī, on October 17, 2024).
The supermoon of March 19, 2011 (right), compared to an average full moon of January 18, 2011 (left), as viewed from Earth
A full moon at perigee appears roughly 14% larger in diameter than at apogee.[17] Many observers insist that the Moon looks bigger to them. This is likely due to observations shortly after sunset when the Moon appears near the horizon and theMoon illusion is at its most apparent.[18]
While the Moon's surfaceluminance remains the same, because it is closer to the Earth theilluminance is about 30% brighter than at its farthest point, or apogee. This is due to theinverse square law of light which changes the amount of light received on Earth in inverse proportion to the distance from the Moon.[19] A supermoon directly overhead could provide up to0.36 lux.[20]
Claims that supermoons can cause natural disasters, and the claim of Nolle that supermoons cause "geophysical stress", have been refuted by scientists.[2][21][22][23]
Scientists have confirmed that the combined effect of the Sun and Moon on the Earth's oceans, thetide,[27] isgreatest when the Moon is eithernew orfull.[28] and that during lunar perigee, the tidal force is somewhat stronger,[29] resulting inperigean spring tides. However, even at its most powerful, this force is still relatively weak,[30] causing tidal differences of inches at most.[31][b]
Total lunar eclipses which fall on supermoon and micromoon days are relatively rare. In the 21st century, there are 87 total lunar eclipses, of which 28 are supermoons and 6 are micromoons. Almost all total lunar eclipses inLunar Saros 129 are micromoon eclipses. An example of a supermoon lunar eclipse is theSeptember 2015 lunar eclipse.
TheSuper Blood Moon is an astronomical event that combines two phenomena: a supermoon and atotal lunar eclipse, resulting in a larger, brighter, and reddish-colored Moon. A total lunar eclipse takes place when the Earth aligns between the Sun and the Moon, causing Earth’s shadow to fall on the Moon. As the shadow covers the Moon,sunlight passing through Earth's atmosphere scatters, filtering out most blue light and casting a reddish hue on the Moon. This phenomenon is often called ablood moon because of its striking red or orange color.
When these two events coincide, the Moon appears both larger and redder than usual, leading to the term Super Blood Moon. This unique alignment creates a visually impressive and rare sight that has inspired folklore and intrigue for centuries. Super Blood Moons are relatively infrequent, occurring about once every few years, making them a notable event for astronomers and skywatchers alike.
^As an average of 1,000 earthquakes ofmagnitude 5 or greater (18 >= magn. 7),[32] and multiple "supermoons", occur yearly, thelaw of truly large numbers guarantees that over a sufficiently-long interval, numerous "large" earthquakes will occur around the time of supermoons. Refuting thenull hypothesis ("there is no relation between the variables") would entail demonstrating evidence for an alternative hypothesis, such as astatistically significant increase in earthquake frequency around the time of certain events. The inverse—formulating a hypothesis, then looking back through already-gathered data to find support (and disregarding unsupportive data)—is known asdata dredging (see alsoTexas sharpshooter fallacy,apophenia).
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