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August 2013 blue moon

Photo of the August 20, 2013 blue moon by Facebook user Gillian Floyd near Toronto, Ontario.

Blue moon rising

August 21, 2013

On August 20, 2013, we saw a blue moon rise over planet Earth -- but despite what many may think, it isn't actually blue. The name is given to the second full moon in a calendar month, a relatively rare occurrence. The name is also used to refer to the third full moon in a season with four full moons. You can read more about both in our Geekquinox blog.