Welcome to my Blue Moon month – a month of celebrating the Moon in conjunction with Becky’s ‘Blue’ Square in July photo challenge.
This will be a month of immense fun for a ‘lunatic’ such as myself and to kick things off, I’m going to look at what constitutes a Blue Moon.
The term ‘Blue Moon’ has a lot to do with luna mechanics and an additional full moon that appears during a specific period of time throughout the year. One can get lost on the internet reading about the origins of the term, however, this is what I discovered thanks to many articles from Space.com to Sky & Telescope, and EarthSky, to the Phrase Finder and MoonGiant and few other sites thrown in for good measure. Here’s what a discovered:
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In the July 1943 issue of Sky & Telescope magazine, in a question and answer column written by Laurence J. Lafleur, Ph. D.*, there was a comment made regarding the term “blue moon”. Lafleur made reference to the 1937 edition of the (now-defunct) Maine Farmers’ Almanac where, on the page for August, the calendrical meaning for the term was given:
“[the Moon] . . . usually comes full twelve times in a year, three times for each season.” Occasionally, however, there will come a year when there are 13 full moons during a year, not the usual 12. The explanation continued:
“This was considered a very unfortunate circumstance, especially by the monks who had charge of the calendar of thirteen months for that year, and it upset the regular arrangement of church festivals. For this reason, thirteen came to be considered an unlucky number.”
So that gives us the origins of the seasonal blue moon.
As for my understanding, I always thought a blue moon was the second full moon in one calendar month. The origins of this interpretation, however, relate to a misunderstanding of the same article and once again, it was in the Sky & Telescope magazine.
On page 3 of the March 1946 issue, American amateur astronomer James Pruett wrote an article, “Once in a Blue Moon,” in which he made a reference to the term “blue moon” and cited Lafleur’s article from 1943.
“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.”
Sadly though, Pruett’s explanation was an incorrect interpretation and it may have been completely forgotten were it not for Deborah Byrd who used it during her popular radio program, StarDate, on January 31, 1980, following which this incorrect blue moon rule spread quickly, and widely (an ’80’s version of ‘going viral’ no doubt). This incorrect interpretation also gained a lot of currency when it appeared as an answer in the 1986 version of Trivial Pursuit.
By 1988, this new definition started receiving international press coverage and, fast forward 30 years, we now discover it is recognised worldwide. Not bad for a misinterpretation. Indeed, Sky & Telescope even turned a literary lemon into some sweet lemonade by proclaiming that it changed both popular culture as well as the English language in unexpected ways.
Meanwhile, alas, the original Maine Farmers’ Almanac rule has become all but forgotten.
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This is a photo I took of a seasonal Blue Moon, ‘the third of four full moons in a single season’.
Ok, so in Australia, May 31 heralds the end of autumn leaving no room for another full moon before officially entering our next season.
To astronomers though, a season is defined as the period of time between a solstice and an equinox (or vice versa). This full moon during May 2016 counted as the third of four to fall between the March equinox and June solstice.
* I found it very difficult to find any information about who Dr Lafleur was, however, I finally found this :