Once In A Blue Moon? Not Necessarily!

You've heard the saying "once in a blue moon", right?  What the heck does it mean?

Well, it refers to the occurance of 2 full moons in one month.  This used to happen every seven years (or so folklore says).  Actually, it's usually once every year, with some exceptions, like 2014 and 2017.   Another type of blue moon is  TWO of them happening in one year (14 full moons in one year).    THIS is the "once in a blue moon" in the saying.  It only happens every 19 years.   

Now that I've gotten my geek on, it's time to leave you so I can get ready to see the moon!