Rare Blue Moon of August 2021 rises tonight. Here's what to expect.

Tonight's August full moon will rise tonight (Aug. 22,) bringing skywatchers a rare seasonal blue moon.
Sunday's full moon, also called the "Sturgeon Moon", reaches its peak at 8:02 AM EDT (1200 GMT). New York City residents will see the full moon rise at 8:47 pm, just after the sun sets at 7 :45 p.m. EDT (1200 GMT). According to The Farmers' Almanac, however, it will be visible in the sky on both Saturday and Sunday nights.

Full moons are when the moon is on the exact opposite side of Earth from the sun. A full moon is usually 12 times per year or three times for each season.

Related: August 2021's full moon is a Blue Moon. Here are the reasons.

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Jenny Carter, a Plano, Texas photographer, spotted the Blue Moon full moon of Jul 2015 hidden behind clouds as she skywatched on July 31, 2015. (Image credit: Jenny Carter / Jenny Carter Photographer

Blue Moon is usually reserved for the second full Moon in a month. August's Sturgeon Moon, however, is considered a Blue Moon according to an older definition. This refers to the third full lunar event that occurs in one season. According NASA, this is summer with four full moons.

NASA's Gordon Johnston stated that the first English use of "Blue Moon" dates back to 1528. He wrote this in the full moon guide for September and August. The term Blue Moon is thought to have its origins in an old English phrase meaning "betrayer moon" or a reference about rare events such as when the moon appears blue due to atmospheric dust. Blue Moon is also used to refer to the second full moon of a month with two full moons.

According to NASA statements, the term "Blue Moon" was first used to describe the second full Moon in a month with two full moons.

According to The Farmers' Almanac, August's full moon was traditionally known as the Sturgeon Moon. This is because it's named after the huge sturgeon fish that lived in the Great Lakes and Lake Champlain.

Related: 2021 Full Moon Names (and More)

This month's full moon has several other names, including the Flying Up Moon. It is a Cree of Ontario name that refers to August as the season when young birds can learn to fly. The Farmers' Almanac lists other names for the full moon, including the Harvest Moon, Black Cherries Moon, Ricing Moon, Harvest Moon, Ricing Moon, and Ricing Moon. Each name represents different seasons or maturing crops and comes from different cultures.

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