Blue Moon

I just ran into a little trivia about the moon. The pictures above are pictures of the moon that I took December 5, 2009. It was a clear, cold night. The pictures are not a blue moon.

What is a blue moon?

A blue moon, the second full moon in the same month, is nothing rare--it happens about once every two and a half years. But a second blue moon in one year only happens about 3 or 4 times per century. The last time this occurred was on March 31, 1999.