Friday's Blue Moon Isn't As Rare As You Think

LOS ANGELES (CBSLA.com) — Once in a blue moon is a phrase that is supposed to imply that what is happening is rare ...

How did that phrase ever past muster? Blue moons are more common than you think.

Officially, there are two definitions of a full moon. One easy, one rather complicated.

Starting with the complicated, a blue moon (you can see one tonight) is the third full moon in a season with four full moons. What? Translation please!

The easy definition. Most years have twelve full moons, one a month. According to InfoPlease, "A blue moon is the second full moon in the same 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). The full moon on Aug. 31, 2012, will be this type of blue moon; it will be the second full moon in one month."

Our first full moon this month occurred on August 1.

Two blue moons in the space of a year? Okay, that is rare. Two blue moons in the space of the same calendar year will happen about every 19 years. And some years, don't have a blue moon. For example, there will be no blue moons in 2014 or 2017.

And tonight's blue moon? Sorry to disappoint. It's not really going to appear blue. The blue moon refers to the occurrence not the appearance. So, if you think you see the moon looking a little blue this evening, that could just be wishful thinking on your part.

The first known recorded reference to a blue moon happened in 1528, according to the Oxford English Dictionary. Historians still debate where the phrase came from.

But the phrase caught on in speech and even in music. Blue Moon of Kentucky? Great song title and there are pop versions, jazz, country. Elvis Presley did it, so did Ray Charles, Patsy Cline, Bill Monroe, LeAnn Rimes, Jerry Lee Lewis. Even Brit Paul McCartney. You name it, they did it. No matter! Kentucky doesn't get any more blue moons than the rest of us!

The first man to walk on the moon, Neil Armstrong, died last weekend. As a fitting tribute, his family asked everyone to look at the moon "and give Neil a wink."

If you want to send pics of tonight's blue moon (blue or not!) send them to streetteam.com and you might see them on the air during Evelyn Taft's weather forecast or in our web slideshow.