What 'Once in a blue moon' literally means
thisisbrandx.com
thisisbrandx.com
(Learned on HN):
http://news.ycombinator.com/item?id=1008761
which cites: http://en.wikipedia.org/wiki/Blue_moon
If that is the case then this is not a blue moon as the first 3 happened in the fall and the 4th is after the solstice. Right?
To save you the effort, The Farmer's Almanac used the definition you just cited, but "2 full moons in a month* is the more commonly used definition.
Or simply gone to nasa.gov:
http://science.nasa.gov/headlines/y2009/29dec_bluemoon.htm
"The modern definition sprang up in the 1940s. In those days, the Farmer's Almanac of Maine offered a definition of Blue Moon so convoluted that even professional astronomers struggled to understand it. It involved factors such as the ecclesiastical dates of Easter and Lent, and the timing of seasons according to the dynamical mean sun. Aiming to explain blue moons to the layman, Sky & Telescope published an article in 1946 entitled "Once in a Blue Moon." The author James Hugh Pruett cited the 1937 Maine almanac and opined that the "second [full moon] in a month, so I interpret it, is called Blue Moon."
I also remember a few years back, there were two blue moons only two months apart, something that only happens every couple decades. There was a full moon in early January, a blue moon on Jan 31st, then the tiny month of February managed to fit in between full moons, so the next full moon happened on March 1st, with a blue moon later that month.
Anyone know why? Any ideas on the causal effect? Pure chance?