Blue Moon is set to rise in the night sky this Friday, August 31. But, do you know what a Blue Moon is, exactly? If you have been wondering about this then keep reading.
First of all, let me make it clear that the term Blue Moon has nothing to do with the color. It is just another full moon. And there is nothing special about the color of the moon.
The term Blue Moon was first traced by ‘Sky and Telescope’ magazine in 1946. Then, the term apparently referred to the third full moon in a season that contains four full moons.
Normally, a season of three months contains only three full moons. But, due to the shorter length of lunar months (29.5 days) compared to solar months, four full moons occasionally get squeezed into a single season.
But the author of the ‘Sky and Telescope’ article misinterpreted this complicated definition, declaring that a Blue Moon is actually the second full moon in a month with two full moons.
In 1980, the new (and wrong) meaning attained widespread usage as it was used during a broadcast of the radio show. And in 1981, the unscientific term became a general knowledge as the developer of a game defined the term as it was defined by the ‘Sky and Telescope’ author.
So that is why Friday's full moon is known as a Blue Moon. It really is no different than any other full moon, except that an accident of the calendar causes it to be the second full moon in the month of August, the first having been on Aug. 1. And, on average, blue moons come along once every 2.7 years.