Blue Moon To Appear Friday
By Steven Strouss
PHILADELPHIA (CBS) -- On Friday morning, just before 7AM, the 2nd full moon of the calendar month will occur. By definition, its a Blue Moon, a rare phenomenon that happens, on average, once every 2.7 years.
The actual name has nothing to do with the color of the moon. During most years, the Earth experiences 12 full moons, one in each month. But in some years, like 2015, we have 13 full moons. The moon was full on July 2, and it will be full again on Friday, July 31 so Friday's moon is called the Blue Moon.
The last Blue Moon was in August 2012 and the next one, after this, will be in January 2018.
On very rare occasions, there can be two Blue Moons in one calendar year and that will happen in 2018, once in January and again in March. The next year of a double monthly Blue Moons will be in 2037.
So the next time you use the phrase once in a Blue Moon you will know that the moon isn't actually turning blue.