How often does something that happens “once in a blue moon” really happen?
I think we've all used the term "once in a blue moon" to refer to an event that doesn't happen very often, but have you ever thought about what a blue moon is, is it really blue and how often it happens? Well, today's your lucky day because I have!First, there is nothing blue about a blue moon. I'm not sure why we say blue (if you know, please post!), but I do know that the current definition (it actually has changed several times over the years) is the second of two full moons that occur in the same month. The lunar cycle is just more than 28 days long while the average number of days in a month is right at 30 days. This means that "once in a blue moon" (pardon the pun), we have two full moons in the same month. This happens about 41 times each 100 years.
This means that when we say something happens "once in a blue moon," we are really saying it happens once every 2.44 years. Of course, saying "once in every 2.44 year time period" just doesn't roll off the tongue as well which for all I know, could be the real reason we say "once in a blue moon."
What do you think?
Posted by on 04/23 at 07:14 AM
The “blue moon” expression itself dates back to mediaeval England..
In the “Treatyse of the Buryall of the Masse”..
..the work of
William Barlow..the Bishop of Chichester..
According to the Oxford English Dictionary, the first reference to a blue moon comes from a proverb recorded in 1528
“If they say the moon is blue,
We must believe that it is true”
In the 19th century..the phrase until a blue moon developed..meaning “never.” The phrase..once in a blue moon today has come to mean “every now and then” or “rarely”...whether it gained that meaning through association with the lunar event remains uncertain…
This knowledge came to me in my time as a knight at the round table..."Sir Google”..they called me..