A Blue Moon

Last night's full moon was a Blue Moon. Though it has nothing to do with the color.
Last night we had a full moon was a Blue Moon, not by the popular definition, but by the original definition. According to the first articles about a Blue Moon in the old Maine Farmer's almanac, a blue moon is the 3rd full moon in an astronomical season that would have 4 full moons. But in 1946, an article in Sky and Telescope misinterpreted the definition and called a Blue Moon the second full moon of a month. Even though it was a mistake, that's become the most common definition.

But last night's full moon was not the second of the month. That won't happen until July of 2015. Though this full moon was the third since the summer solstice in late June and there will be another before the autumnal equinox in late September.
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