What is a super moon? Is today the first supermoon of 2021?

Today, March 28, 2021, we have the opportunity to see the full Worm Moon rise. Today’s moon is especially huge because it is closer to Earth than most other full moons.

Can the “Moon of the Worm” be considered a supermoon? If so, she could start a series of four supermoons in a row.

In fact, it all depends on which definition we choose.

Supermoon rising over Fremantle, Australia

Why is that? It turns out that the terms “supermoon” and “supermoon” do not have an official astronomical definition. In general, the “supermoon” is more an astrological phenomenon than an astronomical one.
What then should we do?

Let’s take a look at everything there is to know about supermoons and why (or why not) today’s full moon is and is not a supermoon at the same time.

According to the creator of the term “supermoon”, astrologer Richard Nolle, we will not be witnessing a supermoon today. His 21st century supermoon calendar includes only two cases in 2021:

  • April 27, 2021 – Pink Supermoon
  • May 26, 2021 – Flower Super Moon.

According to Nolle, “a supermoon is the moment of perigee-syzygy, a new moon or full moon, which occurs when the moon is 90% or more of its average closest distance to Earth.”

Supermoon in 2018 from Lancelin Island, Australia

So, above there are several terms that need to be understood. They are quite simple:

Perigee – This is the closest point to the Earth’s orbit of the Moon (or an artificial satellite of the Earth). The Moon passes the perigee point once a month, since the Moon revolves around the Earth in an elliptical orbit, making one revolution per month.

Syzygy – alignment of three or more astronomical bodies within the solar system on one straight line. Usually they say this about the Sun, Earth and Moon. This event occurs twice a month: on the new moon (when the moon is between the sun and the earth) and on the full moon (when the earth is between the sun and the moon).

That is, the Moon at the moment of perigee-syzygy is a full moon or new moon, at which the Moon is as close as possible to the Earth. At the same time, Nolle claims that the supermoon is one of the 10% of the nearest full or new moons.

In practice, new moons are of no interest to anyone. After all, we don’t even see them. Only full moons are commonly referred to as supermoons.

In 2021, the closest supermoons are estimated to be full moons in April and May, with full moons in both cases occurring less than 12 hours after perigee. But are they the only supermoons?

Well … As we said earlier, there is no official definition for supermoon. Astronomer Fred Espenac defines the supermoon as a full moon at perigee, occurring “within 90% of its closest approach to the Earth in a given orbit.”

So, according to this definition, there are four supermoons in 2021:

  • March 28, 2021 – Worm Supermoon (362,170 km from Earth)
  • April 27, 2021 – “Pink Supermoon” (357 615 km)
  • May 26, 2021 – Super Flower Moon (357,462 km)
  • June 24, 2021 – Strawberry Supermoon (361,558 km).

So, it can be noted that the May full moon is the closest in distance in 2021, followed by the April full moon, then comes June with a significant gap, and a little further is today’s “Worm Moon”.

Supermoon in Redondo Beach, California

To complicate the task, the site TimeandDate.com calls the full moon is a supermoon only when it is within 360,000 km of Earth, and the log Sky & Telescope at all He speaks about 358 884 km. If we take into account both of these criteria, then only full moons in April and May are supermoons.

So, can we call today’s full moon a supermoon? Of course we can, but know that the best supermoons of 2021 are yet to come!

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