Posted on Aug 21, 2021
Why this weekend's Blue Moon is extra rare (and how to see it)
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The saying "once in a blue moon" is especially pertinent this week: This Sunday (Aug. 22), the full Sturgeon Moon is expected to impress skygazers, particularly because of its "blue" designation.
Typically, the term "Blue Moon" refers to the second full moon within the same month. The last one rose on Oct. 31, 2020, when an eerie Blue Moon lit up the night sky on Halloween. But there's a lesser-known definition, dating to 1528, which applies to the third full moon in a season with four full moons, according to NASA.
In general, each season has three full moons. But summer 2021, which began June 20 and ends Sept. 22, has four full moons (June 24, July 23, Aug. 22 and Sept. 20). Seasonal Blue Moons are uncommon, occurring about once every two to three years, according to EarthSky. The last one rose on May 18, 2019, and the next one won't shine until Aug. 19, 2024.
Typically, the term "Blue Moon" refers to the second full moon within the same month. The last one rose on Oct. 31, 2020, when an eerie Blue Moon lit up the night sky on Halloween. But there's a lesser-known definition, dating to 1528, which applies to the third full moon in a season with four full moons, according to NASA.
In general, each season has three full moons. But summer 2021, which began June 20 and ends Sept. 22, has four full moons (June 24, July 23, Aug. 22 and Sept. 20). Seasonal Blue Moons are uncommon, occurring about once every two to three years, according to EarthSky. The last one rose on May 18, 2019, and the next one won't shine until Aug. 19, 2024.
Why this weekend's Blue Moon is extra rare (and how to see it)
Posted from livescience.com
Astronomy
Science Fiction
Space
Posted >1 y ago
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There was, some years ago, two sequential months that had Blue Moons. The second full moon was on the last day of a month continued to the first day of the subsequent month. One lunar orbit later there was another full moon in that month, making two sequential months with Blue Moons. I cannot recall when that happened, but it was remarkable.
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