Tomorrow, July 31, the second full moon of the month will make its appearance. In modern times the second of two full moons in a calendar month has come to be known as a "Blue Moon." However, that's a misnomer. Two full moons in a calendar month were never called Blue Moons until just the last 50 years or so. The term Blue Moon originally described the third of four full moons in a season. Each of the four seasons- summer, fall, winter, and spring- has a total of three full moons (4x3=12, one full moon for each month). Ancient calendar keepers called the third full moon of four in a season a "belewe" moon, an Old English term that meant betrayer. And thus "belewe" evolved linguistically to became the "blue" which we use today. The "Blue Moon" misnomer that describes the second of two full moons in a calendar month can be traced to a March 1946 article in Sky and Telescope magazine. In that article amateur astronomer and writer James Hugh Pruett mistakenly interprets the 1937 edition of the Main Farmer's Almanac definition of a Blue Moon to mean two in a month. This mistake was picked up by other writers and soon became a part our astronomical nomenclature. Blue Moons by this definition occur every two or three years. The last Blue Moon was August 31, 2012, seen in the photo above. The next will be January 31, 2018. To view a blue tinted time-lapse I made of the moon last night click the play icon below. Enjoy.
Video Copyright Michael E. Palmer/Palmer's Almanac
Michael E. Palmer is a writer and photographer based in Alabama.
He can be reached at firstname.lastname@example.org