When is the next Blue Moon?Posted: February 16, 2012
Unless you’re thinking of the 1934 popular song (yes, it’s really that old, I looked it up), there are a couple of different schools of thought about what exactly constitutes a Blue Moon. Earthsky.org fills us in:
In the 21st century, according to folklore, the name Blue Moon has two meanings. A Blue Moon can be the second full moon in a calendar month. Or it can be the third of four full moons in a single season. There will be two full moons in a month on August 31, 2012 – the next scheduled Blue Moon. […]
In recent years, a controversy has raged – mainly among purists – about which Blue Moon definition is better. The idea of a Blue Moon as the third of four in a season is older than the idea of a Blue Moon as the second full moon in a month. Is it better? Is one definition right and the other wrong? After all, this is folklore. So the folk get to decide, and, in the 21st century, both sorts of full moons have been called Blue.