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Blue Moon 2015: When To See The First Since 2012
The next one will be an even bigger milestone.
Once in a blue moon? That’ll be Friday, the first in nearly three years.
A blue moon occurs when there are two full moons in the same month. Because a moon cycle lasts for about a month, the timing has to be just right to get two in the same month.
July 2 was a full moon. July 31 will be, too. Hence, blue moon 2015.
The last time this happened was August 2012, when there was a full moon on August 31 that year.
The next blue moon will be an even rarer event.
Because of their timing coinciding with a leap year, both January and March of 2018 will have a blue moon. The last time that happened was 1999.
To answer a common question: no, the moon won’t actually be the color blue.
While there are some conditions that can cause the moon to appear a shade of blue—smoke, a concentration of certain particles—the name has nothing to do with the moon’s color.
It dates back to a 16th-century piece of literature using the word “belewe,” to betray, to refer to a moon that doesn’t properly mark the end of a farming season.
The “blue” caught on in the early 1900s and now generally refers to two full moons in the same month.
