For all you sky watchers, we are about to experience a Blue Moon tomorrow night. The most common definition of a blue moon out there right now refers to it as the second full moon of a calendar month. I knew there had to be more behind it and Earth Sky science website provided me with the information below.
The idea of a Blue Moon as the second full moon in a month stemmed from the March 1946 issue of Sky and Telescope magazine, which contained an article called “Once in a Blue Moon” by James Hugh Pruett. Pruett was using a 1937 Maine Farmer’s Almanac, but he simplified the definition. He wrote: Seven times in 19 years there were – and still are – 13 full moons in a year. This gives 11 months with one full moon each and one with two. This second in a month, so I interpret it, was called Blue Moon.
EarthSky’s Deborah Byrd happened upon a copy of this old 1946 issue of Sky and Telescope in the stacks of the Peridier Library at the University of Texas Astronomy Department in the late 1970s. Afterward, she began using the term Blue Moon to describe the second full moon in a calendar month on the radio. Later, this definition of Blue Moon was also popularized by a book for children by Margot McLoon-Basta and Alice Sigel, called “Kids’ World Almanac of Records and Facts,” published in New York by World Almanac Publications, in 1985. The second-full-moon-in-a-month definition was also used in the board game Trivial Pursuit.
Can there be two blue moons in a single calendar year? Yes. It last happened in 1999. There were two full moons in January and two full moons in March and no full moon in February. So both January and March had Blue Moons.
The next year of double blue moons is coming up in 2018.
Blue moon as third full moon of four in a season. The Old Farmer’s Almanac defined a Blue Moon as an extra full moon that occurred in a season. One season – winter, spring, fall, summer – typically has three full moons. If a season has four full moons, then the third full moon may be called a Blue Moon. The next blue moon by this definition will fall on August 21, 2013.
In recent years, a controversy has raged – mainly among purists – about which Blue Moon definition is better. The idea of a Blue Moon as the third of four in a season may be older than the idea of a Blue Moon as the second full moon in a month. Is it better? Is one definition right and the other wrong? After all, this is folklore. So the folks get to decide, and, in the 21st century, both sorts of full moons have been called Blue.
So whether you define a Blue Moon as the second full moon in a month – or the third full moon of four in a season – the name Blue Moon accounts for times when there are more full moons than is ordinary.
Last nights sunset was pretty cool there was a lot of rainbow color action happening to the left of the sun, my pictures do not do it justice as to what we actually saw. I heard Mary Beth mention something about a sun dog also known as a solar halo and ice crystals but I did not quite catch it all.