Once in a Blue Moon…

July 29, 2015: “Once in a Blue Moon” is actually going to happen this Friday! More specifically, a full moon will occur late Thursday night into Friday morning.  The “Blue Moon” is the term for the 2nd full moon of the month (and not because it turns blue).

Click on image to enlarge.

Click on image to enlarge.

While the phrase “once in a blue moon” is used to describe something rare, the actual occurrence of a blue moon isn’t all that rare. The average lunar cycle (from full to new and back again) lunar cycle is 29 1/2 days, so almost every month can have 2 full moons if the timing is right. I say almost because February is the only month that can’t.  Sorry February; 28 days just doesn’t cut it.

The definition of the blue moon has changed a little within the last few decades.  It used to mean the 3rd full moon in a season (spring, summer, etc.) with 4 full moons. A misunderstanding eventually lead to the current definition of 2 full moons in a month. No matter what the moon is called this time around, see if you get the chance to take a peek and enjoy the view Thursday night!

– Alex


Posted under event, science, space

This post was written by Alex Kirchner on July 29, 2015

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