August Blue Moon is also a supermoon: When to watch and what to expect

The August 30 full Moon is both a Supermoon and a Blue Moon. Here is what that means.

A supermoon acn be seen as it rises behind the US Capitol on March 9, 2020. (NASA/Joel Kowsky)

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The full Moon on August 30 will be a rare combination of two different phenomena—a Blue Moon and a supermoon—and we will not see this happening again till 2037.

What is a supermoon?

The Moon’s perigee with Earth is when the Moon is at its closest point to the Earth in a month. Once in a while, this coincides with a full Moon. At that point, it becomes a supermoon. A supermoon appears slightly larger and brighter than a run-off-the-mill full moon. The August 30 full Moon coincides with the Moon’s perigee, making it a supermoon.

What is a blue supermoon?

The phrase “once in a blue Moon” is often used to refer to things that happen very rarely. But the real-world meaning of “Blue Moon” does not actually involve the Moon turning blue. Instead, there are two other definitions. The more common definition of a blue moon refers to when a full Moon appears for the second time in a month, according to NASA. We already had a full Moon on August 1, which makes the August 30 full Moon a blue moon.

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How rare is a blue supermoon?

A blue Moon by itself is a fairly rare phenomenon. According to the American space agency, it happens about once every two-and-a-half years on average. Full Moons are separated by 29 days, and since months are 30 or 31 days long, there is a good possibility of two full moons fitting within a month.

Supermoons are a lot more common. You can expect three or four every year. But a blue moon coinciding with a supermoon is a very rare phenomenon. While the next monthly blue Moon will happen as early as August 2023. Interestingly, the next two super blue moons will happen almost one after another, in January and March 2037, according to NASA.

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