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What is a Supermoon and When Does it Occur?

The full moon on June 24, 2021, is the year’s final so-called “supermoon,” dubbed the “Super Strawberry Moon.” But what is a supermoon, when do they happen, and are they really worth getting excited about? Supermoons occur at perigee, the closest point in the Moon’s orbit to Earth. A perigee full Moon appears brighter and larger than an average full Moon, and is referred to as a ‘supermoon’ by some. However, astronomers generally do not use these and the technical name for a ‘supermoon’ is a perigee syzygy Moon.

A supermoon occurs when the Moon’s orbit is closest to Earth (perigee) and the Moon is full. So, what’s the big deal about a supermoon? There’s a lot to see and learn for the curious observer.

  • The Moon orbits Earth in an ellipse, an oval that brings it closer and farther away from Earth as it rotates.

What is a Supermoon and When Does it Occur?

  • The apogee is the farthest point in this ellipse and is approximately 253,000 miles (405,500 kilometers) from Earth on average.
  • Its closest point to Earth is the perigee, which is approximately 226,000 miles (363,300 kilometers) away.
  • When a full moon appears at perigee, it is slightly brighter and larger than a regular full moon – this is where the term “super moon” comes from.

The orbit of the Moon around the Earth

What is a Supermoon and When Does it Occur?

The Moon takes slightly more than 27 days to orbit Earth on an elliptical path that takes it from its farthest point from Earth at apogee to its closest approach at perigee. These distances can range from 406,712km (apogee) to 356,445km (perigee). It also takes just over 29 days to cycle from one full Moon to the next, as you can see if you keep track of the Moon’s phases night after night. Meanwhile, the Earth’s orbit around the Sun lasts 365 days, which means it takes 14 lunar cycles (411 days) to travel from one full perigee Moon to the next. The first of three consecutive super moons in 2021 occurred in April 2021, but this is not unusual.

Indeed, as the Moon orbits Earth, the series of full Moons cycles from largest to smallest and back again every 14 lunar months. Perigee can last anywhere from two to five full Moons. For a full Moon to be classified as ‘super,’ it must occur at a distance of 360,000 kilometers or less from Earth, so full Moons that occur on either side are also classified as super moons. We get two or four supermoons in a row on rare occasions, but three is the most common.

What is a supermoon?

What is a Supermoon and When Does it Occur?

A super moon is a new or full moon that occurs at or near perigee, the moons closest point to Earth in its monthly orbit. Once a month, the moon is full, or opposite Earth from the sun. Once a month, it is new, or more or less between the Earth and the sun. And, every month, the moon comes closest to Earth, or to perigee, in its elliptical orbit around Earth. The moon naturally swings the furthest away once a month as well; this point is known as apogee. Every year, the new or full moon coincides closely with perigee on a few occasions; this is when we have a super moon.

The term super moon was coined in 1979 by astrologer Richard Nolle. It stated that a super moon is a full or new moon that comes within 90% of its closest approach to Earth. EarthSky is using super moon dates determined by astronomer Fred Espenak for 2022. His method accounts for changes in the moon’s orbit throughout each lunar cycle. The term emphasizes the geometric alignment of the Sun-Earth-Moon and allows the occurrence of perigee to occur over a longer time period than the actual instant of perigee.

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What distinguishes a super moon?

What is a Supermoon and When Does it Occur?

Some lunar perigees are more distant than others. The Moon’s orbital shape evolves over time (thanks to the gravitational influence of the Sun and the other planets). Extreme perigees and apogees, or the farthest point in the orbit, occur on a regular basis. It’s unusual to have a full moon and an extreme perigee occur at the same time. The angular radius and diameter of an extreme perigean full moon will appear slightly larger than at other full moons. Let’s go to November 13-14, 2016, when the radius and diameter of the extreme perigean full moon were:

  • Less than 2% larger than a typical perigean full moon.
  • Less than 8% larger than the appearance of the full moon at its average distance from Earth.

The average apogean full moon is less than 14 percent larger. When held at arm’s length, the width of your smallest fingernail is about the same diameter as the full moon in the sky.

When is the next supermoon?

In the year 2022, there will be two Super Moons: the Super Strawberry Moon on June 14 and the Super Buck Moon on July 13. However, there will be two Super New Moons. The first will take place on January 2, and the second will take place on December 23. (The date may vary depending on your time zone). The Super New Moons, like any other New Moon, will not be visible from Earth, but the dark night skies will provide excellent opportunities for stargazing, particularly around January 3, when the Quadrantids peak. The December Super New Moon will coincide with the peak of the Ursids meteor shower, and it will also be an excellent time to see Mercury in the night sky.

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Supermoons 2022

Here are the supermoons, both full and new moons, for 2022.

2022 full moon supermoons

These values — date and moon’s distance — are from Fred Espenak’s full super moon table.

  • May 16 362,127 km (225,015 miles)
  • June 14 357,658 km (222,238 miles)
  • July 13 357,418 km (222,089 miles)
  • August 12 361,409 km (224,569 miles)

The July 13 super moon is the closest super moon for 2022; on that day, the full moon aligns with the lunar perigee – the moon’s closest point to Earth in its monthly orbit – which also falls on that day. Naturally, the closest and thus largest full moon of the year will result in higher-than-usual perigean spring tides, which people living near the coast will undoubtedly experience.

2022 new moon supermoons

Fred Espenak does not have a new moon super moon table. However, we can deduce this from other tables on his website. More information is provided in the section below, but in the meantime, here are the new super moon dates and the moon’s distance from Earth on those dates.

  • January 2 358,044 (222,478 miles)
  • February 1 364,505 (226,493 miles)
  • December 23 360,013 (223,702 miles)

Super Full and new Moon

When a Full Moon occurs near the Moon’s closest approach to Earth, it is referred to as a Super Full Moon. A Super New Moon occurs when the New Moon is at its closest point to Earth. A Micro moon, on the other hand, occurs when a Full or New Moon is near its most distant point from Earth, around apogee. It is also referred to as a Mini-moon, Mini Full Moon, or Mini New Moon.

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When a full Moon coincides with the Moon’s closest approach to Earth along its orbit, it is called a super moon. Every year, there are 12 or 13 full Moons, but due to the orientation of the Moon’s orbit, not every full Moon is a super moon, just as not every full Moon is a lunar eclipse.

Effects of Supermoon

There is little scientific evidence to support claims that super moons cause earthquakes, volcanic eruptions, extreme weather and tsunamis, or floods and pestilence! Of course, the Moon is the driving force behind Earth’s tides: full and new Moons are when the Earth, Sun, and Moon align to produce extreme spring tides, but perigean spring tides only increase tidal variations by about 5cm on average. There have been a few tsunamis and earthquakes in recent years that coincided with a super moon, but with three super moons every 14 months, it would be unusual if such a disaster did not occasionally coincide with a super moon. A super moon may not be so ‘super,’ or even rare, but it is still a great way to interact with our nearest celestial neighbor once you get past the hype.

Tides at Supermoon

What is a Supermoon and When Does it Occur?

Around the Full and New Moons, the difference between high and low tide is greatest. During these phases of moon, the Moon’s and Sun’s gravitational forces combine to pull the ocean’s water in the same direction. Spring tides or king tides are the names given to these tides. Supermoons cause a 5 cm (2 inch) increase in variation over regular spring tides, known as perigean spring tides. The tidal range is at its narrowest during the two Quarter Moons, which are known as neaps or neap tide.

What Causes Tidal Waves and What is Tidal Energy?

The extra gravitational pull of super moons is felt by Earth’s oceans. All full moons (and new moons) interact with the sun to produce larger-than-normal tides known as spring tides. However, super moons – closer-than-average full moons (or closer-than-average new moons) – raise the tides even more. These extra-high spring tides have a wide range of effects. On the same day, high tides rise unusually high and low tides fall unusually low. These are known as perigean spring tides, after the moon’s proximity. Keep an eye out for them if you live near the ocean! They usually arrive a day or two after the super moon. Is flooding caused by super moon tides? Perhaps, and perhaps not. Flooding usually occurs when a strong weather system coincides with a particularly high spring tide.

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