Once in a Blue Moon…
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If you’ve been waiting for something that happens “once in a blue moon” tonight’s your night!
You might be saying “wait a minute! there weren’t two full moons this month!” – and you’d be right!
With that said, a quick explanation of the origins of the term “Blue Moon” is in order.
The modern definition of a Blue Moon is the second full moon of a month, however that definition comes from an issue of Sky and Telescope Magazine from 1946 and has been perpetuated by the media ever since.
However, the “true” definition is that a “Blue Moon” is the third full moon when a season has four full moons,which is so the final new moon can remain the “late moon”.
Again, you might be saying “Wait again! December’s full moon is on the 21st! – That’s the first day of winter!”
You’d be right if you said that too! But…… the full moon occurs at 8AM universal time, and the solstice doesn’t occur until around 1130 PM universal time. Sure, it’s a technicality, but rules are rules. With four full moons this autumn (Sept 23rd, Oct 22nd, Nov 21st and Dec 21st) Tonight’s full moon qualifies as a blue moon.
So if someone has said you only do something “once in a blue moon” you’d best be doing it tonight!
Image courtesy of Luc Viatour:
Ray Sanders is a Sci-Fi geek, astronomer and blogger. Currently researching variable stars at Arizona State University, he writes for Universe Today, The Planetary Society blog, and his own blog, Dear Astronomer
2012-12-04 08:05:09
Source: http://www.dearastronomer.com/2010/11/21/once-in-a-blue-moon/
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