What & When is a Blue Moon?

Enchanted Circle of Witches®

There are two astronomical definitions of a Blue Moon; both are a type of Full Moon. When the Moon very rarely actually looks blue, it’s because of a certain size dust particles in the atmosphere.

Illustration image
Blue moons are rarely blue
©bigstockphoto.com/Kamira

The next Blue Moons

YearDate
2015Friday, July 31
2016Saturday, May 21

Once in a blue moon means very rarely. But just how rare depends on your definition.

In astronomy, Blue Moon is defined as either the third full moon of an astronomical season with four full moons or the second full moon in a calendar month.

Such a blue Moon (second full Moon in single calendar month) will next occur on Friday, July 31, 2015 at 10:43 am UTC.

Contrary to popular belief, a blue moon is not actually blue in color. Blue moon is a term that is used to describe the third full moon…

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