|NASA Picture of the Day|
Did you see last night’s glorious blue moon? And if so, did you see it shining behind the scaffolded Capitol dome? No matter – you can see it now:
If you are thinking, this is something you don’t see very often, then you are using the phrase “blue moon” exactly right. While many people think “once in a blue moon” means something that virtually never occurs, a careful and correct use of the term is reserved for something that occurs only occasionally, perhaps every couple of years. A full moon is called a “blue moon” by almanac and calendar makers* when it is the second full moon within the same calendar month. And it’s something we all have a chance to see multiple times over the course of our lives, as the interval between blue moons is seldom longer than three years.
We can expect the next blue moon on Saturday, May 21, 2016. But the next two after that, in 2018, will be really something special, as 2018 is a double blue moon year – a true rarity. The last time there was a double blue moon year was 1999. For the next double blue moon year after 2018 you’ll need to wait patiently until 2037. (More info on this at http://bit.ly/1eL5x8H.)
As you can see from these photos - http://bit.ly/1IwfSNw - there’s nothing about a blue moon that’s actually blue. But there is another type of blue moon that has nothing to do with the calendar; it’s literally blue. That happens only when there’s been a volcanic eruption or some other accumulation in the night sky of the right kind of ash or particulate matter to catch and reflect a bluish glow onto the moon. And it’s something we will never see here in Washington, DC, no matter how many years we wait. Chalk it up to our lack of volcanoes.
If all this talk of blue moons has got the song “Blue Moon” running through your head, then let Sinatra sing it for you while you watch this charming compilation of images of last night’s blue moon from around the world, courtesy of the BBC: http://www.bbc.com/news/world-33745560
* I realize I need to footnote an older, now somewhat abandoned understanding of the term “blue moon.” The original almanac maker who coined the term intended it to describe an “extra” full moon during a three-month season. Normally, there are three full moons in a season, but if there happen to be four full moons in a season, traditionally, farmers would call the third of the four full moons a “blue moon” (Aren’t you glad you now can distinguish between these two different definitions? Not that it will ever be of any use to you to know this…. But if you are the type to enjoy knowing this sort of trivia, then you will want to watch all of NASA’s five-minute primer on the subject: http://1.usa.gov/1gyLJXX.
Still Life With Robin is published on the Cleveland ParkListserv and on All Life Is Local on Saturdays.