Look Skyward: Blue Moon

Tonight the full moon rose here in spectacular fashion; it looked like something auditioning for Resident Evil.  This is a blue moon, and Space.com is running an interesting article explaining why.  It also gives a little history of blue moons.  The original rule of thumb was that when a season has four full moons instead of the usual three, then the third moon in that season is blue.  This is the third full moon this autumn in the Northern Hemisphere.  Because blue moons are rare, they are surrounded by superstitions.  The thirteenth full moon of the year - brought about by a blue moon - is considered unlucky because it messed up the calculation of church calendars.

Yahoo has a piece by Timothy Sexton on the superstitions here:

"The blue moon is not only a metaphor for something that occurs rarely, but it also has a history of portending luck ... . Superstition ... has that the occurrence of a blue moon is the perfect time to plant the seeds of long-term goals that will blossom in the sun of a future day. ... Unfortunately, the magic of the blue moon is unpredictably intense. To put in motion your goals for the future underneath the moon at the end of the month is the same thing as making a wish granted by a genie. If you don't use very careful and precise language, the result may very well be a sweet cookie full of arsenic. The potency of the magic of the blue moon is said to be concentrated and passionate; you may get what you wish for but in a way not foreseen ... ." 

So if you plan something tonight, factor in the unexpected.  This is apparently why the moon is called 'blue.' It's not because it is literally a blue colour, but because a blue moon is a 'false' or 'trickster' moon.  It's a doppelgänger - a mysterious double, an extra fake full moon that has somehow slipped into the calendar.  According to Wiki, the colour blue was sometimes symbolically associated with betrayal and deception.