A full blue moon will show in the skies tonight for the first time in two and a half years.

You've heard the expression, "Once in a blue moon" and probably thought that meant it only happens once or twice a lifetime.

The fact is, the stretch of time is almost 30 months. After tonight, you’ll have to wait another 36 months — until July 2015 — for the next one. So, it’s time to loosen up Friday and do all those things you say you do “once in a blue moon.”

So find a comfy spot tonight and enjoy!