Once in a Blue Moon? That's something we say when talking about a rare event. But what in the world is a "blue moon"? It's actually a real astronomical term , meaning a full moon that occurs twice in the same month. It's an extra moon.

This Friday, August 31, look up in the sky and you will see a blue moon. The first full moon in August was on August 2nd. Mind you, the moon won't look blue. It will look like any other full moon.

So if you're looking for something exiting to do this Friday night, take your lawn chair, a 6-pack of Blue Moon beer, find a good spot away from trees and anything else that could block your view, and look at that "Blue Moon Of South Dakota"(not Blue Moon of Kentucky).

The next time you'll be able to see a blue moon is July 2015.