Gary Seronik According to the Maine Farmers' Almanac, a Blue Moon occurs when a season has four full Moons, rather than the usual three. Click on the image or here for a larger version. Its craters, mountains, and other surface features appear muted because the high Sun casts no shadows as seen from our earthbound perspective. Thus it rises at sunset and sets at sunrise. When the Moon is full, it is opposite the Sun in the sky. Permission is granted for nonexclusive use in print and broadcast media, as long as appropriate credits (as noted) are included. Sky & Telescope is making the illustrations below available to editors and producers. As you wait for the Blue Moon to rise on August 22nd, you could treat yourself to a Blue Moon cocktail: In a tall glass filled with ice, mix four parts of gin to one part of blue curaçao and add a twist of lemon. Popular culture has also enthusiastically adopted the phrase “Blue Moon” and applied it to many different things. Only exceedingly rarely does the Moon actually turn blue in our sky - when volcanic eruptions or forest fires send lots of smoke and fine dust into the atmosphere. Historically, the term “Blue Moon” was more often not an astronomical term: In older songs it's used as a symbol of sadness or loneliness, while “once in a blue Moon” means a rare event. This means that observers in the Americas will see nearly full Moons on two successive nights - August 21–22 and August 22–23 - with the Moon appearing closest to full before dawn and again after dusk on the 22nd. Eastern Daylight Time (12:01 Universal Time), after the Moon has set as seen from the U.S. The Moon will be exactly full (that is, directly opposite the Sun) this month at 8:01 a.m. The next second-full-Moon-in-a-month Blue Moon comes in August 2023. We get a “Sky & Telescope” Blue Moon after a full Moon occurs on the first or second night of a month having 30 or 31 days, respectively there can never be this type of Blue Moon in February, because full Moons occur 29.5 days apart. The last such occurrence was in February 2019, and the next after this month’s will be in August 2024. We get a “true” Blue Moon when the cycle of lunar phases causes the full Moon to occur within a few days after an equinox or solstice. They happen about once every 2.7 years on average.
Olson, along with research librarian Margaret Vaverek at Texas State University, worked with the magazine’s editors at the time to figure out the origin of the mistake, and how the two-full-Moons-in-a-month meaning spread into the English language.īy either definition, Blue Moons are still relatively rare. Sky & Telescope admitted to its “Blue Moon blooper” in the March 1999 issue (see “ What Is a Blue Moon in Astronomy?”). “Introducing the ‘Blue’ Moon meant that the traditional full Moon names, such as the Wolf Moon and Harvest Moon, stayed in synch with their season,” says Diana Hannikainen (pronounced HUHN-ih-KY-nen), Sky & Telescope’s Observing Editor.īut in 1946, amateur astronomer and frequent contributor to Sky & Telescope James Hugh Pruett (1886–1955) incorrectly interpreted the Almanac’s description, and the second-full-Moon-in-a-month usage was born. he Almanac consistently used the term to refer to the third full Moon in a season containing four (rather than the usual three). This colorful term is actually a calendrical goof that worked its way into the pages of Sky & Telescope in March 1946 and spread around the world from there.Įditors and contributors to Sky & Telescope have traced the traditional astronomical definition to the Maine Farmers’ Almanac in the late 1930s. In modern usage, “Blue Moon” has come to refer to the second full Moon in a month (the last of these occurred on October 31, 2020) - but that hasn’t always been the case. The full Moon of Sunday, August 22nd, will be a “Blue Moon” according to the original - but not the most popular - definition of the phrase. Note to Editors/Producers: This release is accompanied by high-quality graphics see the end of this release for the images and links to download.
Rick Fienberg, Press Officer, American Astronomical Society Diana Hannikainen, Observing Editor, Sky & Telescope