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Blue Moons

Blue Moons

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Why is it called a "Blue Moon"?

Thanks! Terri C


Great question!

Tonight's moon on the 31st of May is a blue moon. It is the second full moon in a month, this second moon is named a blue moon.

The name "Blue Moon" can mean one of two things. Either the second full moon in a month or it can actually be a moon with a bluish tint. You could have this tint from some sort of aerosols being in the air from something like a volcano. Or there could be a lot of water droplets in the air.

More popularly, the blue moon is the 2nd full moon of the month. The prhase has been around for 400 years and its meaning has changed through that time. The modern definition came from an issue of Sky and Telescope magazine in the 1940's when one author was trying to clarify the definition. Since then, it's commmonly the 2nd full moon in the month.

There is a great article from NASA on the right side of this page to learn more!

Answered by KSL Meteorologist Dina Freedman.

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