A New Year and a Blue Moon
The second full moon
in a single month is a fairly rare occurence, rare enough that it's called a blue moon. A blue moon occurs every 2.7 years because our twelve month calendar doesn't quite match the lunar cycle or the time it takes for the moon to revolve around the Earth. A lunar cycle takes 29 days, 12 hours, and 44 minutes. Roughly. I should note that the moon doesn't, unfortunately, turn even slightly blue, but it's still an additional opportunity to view a full moon.
New Year's eve this year is a blue moon; we've already had one on December 2. But it's even more nifty than that. First, while a blue moon occurs about every 2 and a half years, we haven't had one on New Year's Eve since 1990.
