Blue Moon

Blue Moon: IN MODERN times, the term “blue moon” is most often defined as the second full moon occurring within a single month. By a somewhat older definition, it’s the third full moon in a season that has a total of four full moons instead of three. Either way, it’s an out-of-the-ordinary phenomenon that occurs only once every few years.

“Blue moon” was understood in a much more literal way historically, writes folklorist Philip Hiscock in the pages of Sky & Telescope. Once upon a time, he says, it denoted a phenomenon even rarer than an extra full moon, one that has occurred perhaps only once or twice in recorded history: the face of moon literally appearing to turn blue in color.
Read Full Story: The USA News