"Blue Moon" Appears in Sky Saturday Night 154
ArbiterOne writes "Tonight a rare spectacle can be seen: the second full moon in a month, which is sometimes called the "blue moon", according to CNN. Don't be disappointed if it isn't actually blue, though; the blueness is caused by increased density of smoke or ash in the air, such as after a volcanic eruption."
two full moons not originally "blue moon" (Score:1, Informative)
This is caused by ash or other particles in the air and the light reflecting from the moon is filtered through said air and is 'tinted'.
Every so often you see a "red moon" when the moon is close to the horizon. The refraction of the light traveling through the atmosphere makes it appear red.
At least the above was the original definition of "blue moon". Over the years the definition has changed to mean three things [wikipedia.org]. One of which is the two full moons. The later definitions were created more out of ignorance.
The Marcels (Score:1, Informative)
Without a dream in my heart
Without a love of my own
Blue Moon, you knew just what I was there for
You heard me saying a prayer for
Someone I really could care for
And then there suddenly appeared before me
The only one my arms will ever hold
I heard somebody whisper, "Please adore me"
And when I looked, the moon had turned to gold
Blue Moon, now I'm no longer alone
Without a dream in my heart
Without a love of my own
Re:Rare? (Score:5, Informative)
I heard that the adoption of the term blue moon in modern usage actually stems from a misappropriation of the term from some Native American tribe (around the time frame you mention, early 19th C). The term, as far as my uninformed and caffeine-addled mind can conjure at the moment, originally referred to an occurrence of a particular full moon that occurred during the three-month harvest season; specifically, when four moons occurred during this three month season, the third of the sequence was called a "blue moon". (The Wikipedia entry [wikipedia.org] seems to make reference to this--see the second entry--but I can't find anything specific on it. Also, it doesn't seem to mention the "harvest" season, just any season, which is not what I heard from my unreliable source.)
This is why our concept of blue moon as the second in a month doesn't seem to make sense in terms of rarity...it's not that rare. It makes a bit more sense if we consider how often four moons occur during the three month harvest season. That was probably quite a bit more rare.
interesting article about it in sky & telescop (Score:5, Informative)
From the article:
Blue moon explained (Score:3, Informative)
Mead moon and Nanci Griffith (Score:3, Informative)
The first moon in July is known as the "Mead Moon" [waningmoon.com].
A real nice song about the rarity of a Blue Moon is by Nanci Griffith [amazon.com].
Re:Rare? (Score:5, Informative)
Re:I wonder how it affects global tides? (Score:5, Informative)
Still a chance for a `true' blue moon ... (Score:3, Informative)
Fortunately, there is a chance of a real blue moon [reuters.com] if you live near Anchorage, Alaska. Actually, it's not really a fortunate thing, because if this volcano does erupt and spew ash everywhere, it's a big mess. It mucks up your car, you don't want to breath it, it's almost caused airplanes to crash, etc. But it does have the possibility of causing the moon to appear truely blue.
Re:Black Moon is even more rare (Score:5, Informative)
That would make it 2018 then? b.t.w. I don't think it's "usually february", I think it is always february. Every month other than february is guaranteed to be longer than the synodic period (about 29.5 days), so is guaranteed to contain a full moon. (apart from the month in which you change from julian to gregorian calendars...)
Re:Black Moon is even more rare (Score:2, Informative)
The last time there was no full moon in a month was February, 1999. The event was related to there being a Blue Moon in both January and March of that year.
Black Moon can also refer to two new moons in one month. The last time it happened was May, 2003. The next time will be December, 2005.
And let us not forget the Cheshire Moon. This name refers to a new or crescent moon where the line of the crescent looks like a smile or bowl instead of the typical "C" shape.
The explanation given here: [usatoday.com]
Re:Rare? (Score:5, Informative)
Re:Not all that rare (Score:4, Informative)
The 17 blue moons in 20 years is due to two different definitions of what constitutes a blue moon. So, blue moons are twice as common, because there are two different ways to define what a blue moon is!
Re:Not all that rare (Score:3, Informative)
I don't know how infoplease.com counted blue moons to get 17 in the next twenty years, unless it was counting both the 2nd-in-a-month and the 4th-in-a-season varieties. Ask this blue moon calculator [obliquity.com] to list the blue moons between 2004 and 2024, and it lists nine of them (of the 2nd-in-a-month kind).
That's about every 2.2 years.
Re:Black Moon is even more rare (Score:3, Informative)
Of course, as someone pointed out, a "back moon" would imply
two blue moons in that year [blibbleblobble.co.uk]
So are we supposed to give them different names, or is it not possible to uniquely identify each moon in 2018? January Blue Moon and March Blue Moon or something?
And can you change when blue moons occur by selecting an appropriate timezone, or by changing to daylight-savings-time just before a full moon?
Blue photo at Astronomy Picture of the Day (Score:2, Informative)
Re:Black Moon is even more rare (Score:1, Informative)
Re:I wonder how it affects global tides? (Score:3, Informative)
Re:Not all that rare (Score:2, Informative)