Will the moon really have a blue color next Saturday on March 31, 2018? A viral Facebook video would seem to suggest that is what will happen but this is not really true. We've embedded the Facebook post below:
It was published on March 27, 2018 (archived here) with following caption:
Spread this so everyone can enjoy
While it is true that there will be an astronomical phenomenon going on this Saturday called a "Blue Moon" this has nothing to do with the color. The Moon continually goes through several phases in a 28-day cycle, meaning that more or less of the Moon is visible at any given time during the 28-day period:
Roughly speaking each month has one Full Moon, when it is completely visible and there are about three appearances of a Full Moon to a season since seasons last for three months.
But since most months have more than 28 days sometimes a month will have a Full Moon twice, or a season might have four of them. The second Full Moon in a month or the third Full Moon in a season that has four of them is also called a "Blue Moon". (source: timeanddate.com)
A Blue Moon is not that incredibly rare, it generally happens every two years or so. The Moon actually appearing blue is much rarer and only happens if there is a lot of atmospheric dust present, for example after a big volcanic eruption. But none of these have been reported recently so if you tell your friends to "look up at the sky this weekend because the Moon will be blue" you will end up looking like a lunatic to them when all they see will be a regular boring Full Moon.
