A Blue Moon will light up the night sky this evening, August 20-21 from dusk till dawn! This Blue Moon does not fall into the typical definition of the term, the second of two full moons to occur in the same calendar month. Also, the moon is not likely to be blue in color(that’s only caused by highly rare atmospheric conditions).
The August 2013 full moon marks the third of four full moons to fall in the period of time in between a solstice and an equinox. This full moon is the third of four full moons to take place in between the June 2013 solstice and the September 2013 equinox. This makes the August 2013 full moon a Blue Moon!