This Friday night will be the rare "once in a blue moon. There are two definitions of "Blue
Moon"
From Wikipedia, "A blue moon is an additional full moon that appears in a subdivision
of a year, either the third of four full moons in a season or, a second full moon in a month of
the common calendar."
The second definition of "Blue Moon," the second full Moon in a calendar month was popularized due to a miscalculation published in a 1946 article in Sky and Telescope
magazine. Such Blue Moons occur frequently - at least once every two or three years.
The moon rarely appears blue, though it has happened due to atmospheric conditions,
volcanos, pollution, etc.
Large version of the moon, 07.31.2015 1:05 am, over the Emerald Canyon.
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