There is a full moon every month, however, because the lunar cycle and the calendar year are not perfectly synched, there can be a second full moon in the same month. This second full moon is called a Blue Moon, not because of its color, but because it only happens once every 2.72 years. The moon may appear to be blue, but that would be because smoke or dust particles are in the atmosphere from something like a volcanic eruption or forest fire.
So if you ever wondered where the phrase “once in a blue moon” came from, it means something so rare that you might not see it in your lifetime. Therefore, tonight, Friday, July 31st, go out and take a look at the moon! You will not have another chance to see a second full moon in one month again until January 31, 2018!
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