It’s 2021’s only blue moon — in this case, the third full moon to occur in a calendar season with four full moons, which is one more than the typical three.

Blue moons are a phenomenon where there's an extra full moon in a calendar year outside of the usual 12. ... "There's going to be a full blue moon on 31 October 2021," reads an Oct. 18 Facebook post.

The Blue Moon is seen at the Independence Monument in São Paulo Brazil, on Aug. 22, 2021. (Image credit: Amauri Nehn/NurPhoto via Getty Images) The full moon shines over St. Isaac's Cathedral in ...

Related: The August 2021 full moon is a Blue Moon. Here's why. $89.99 at Amazon. ... While the term Blue Moon is commonly reserved for the second full moon of a calendar month, ...

That’s the official definition of a “seasonal Blue Moon,” though a more popular definition is of a “monthly Blue Moon” when there are two full Moons in the same calendar month.

The next blue moon is not due to take place until 2023. ... Blue Moon 2021 Photos Show Stunning August Full Moon Around the World. Published Aug 23, 2021 at 5:50 AM EDT. By Ed Browne .