Blue Moon

So, I swore it would be a Blue Moon if I ever hit my 30's, and sure enough, I was correct. I turned 30 AND there's a Blue Moon, all in the same month.

A blue moon is the second full moon in a calendar month. For a blue moon to occur, the first of the full moons must appear at or near the beginning of the month so that the second will fall within the same month (the average span between two moons is 29.5 days). May 2007 will have two full moons: the first on May 2, the second on May 31—that second full moon is called the blue moon.

Note that the May 31 date applies to most of the Western Hemisphere, including the United States. In the Eastern Hemisphere, the full moon in question will occur on June 1. For that half of the world, the blue moon will be on June 30, 2007.

Over the next twenty years there will be a total of 17 blue moons. No blue moon of any kind will occur in the years 2006, 2011, 2014, and 2017.

The more recent phenomenon, where the blue moon is considered to be the second full moon in a calendar month, last occurred on July 31, 2004. Two full moons in one month may occur in any month out of the year except for February, which is shorter than the lunar cycle.