Blue Moon

The almanac tells us that tonight, November 21, is a "blue moon," defined on this occasion as the third full moon in a season with four full moons instead of the usual three. It only happens once every few years. Historically, the phrase was understood in a much more literal way, however. According to folklorist Philip Hiscock, "blue moon" once denoted a phenomenon even more rare than a season with four full moons — so rare, in fact, that it has probably occurred only once or twice in all of recorded history. Read more...