"Blue Moon" Appears in Sky Saturday Night

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."

Not all that rare

It's not that much of a rare occurrance .. Once every 2.7 years [google.com], even.

Re:Not all that rare

The moon's cycle is about 29.5 days, which makes about 12.4 full moons a year. That means a blue moon about every 3 years.

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

Oh shit !! My friends say I only buy a round of drinks every blue moon - its going to be a very expensive night in my local pub this evening.

ARgh!

Now I have to do all that stuff I told everyone I would only do when the moon turns blue. *sigh*

Rare?

From TFA:

The phrase "Once in a blue moon" was first noted in 1824 and refers to occurrences that are uncommon, perhaps even rare. Yet, to have two full Moons in the same month is not as uncommon as one might think. In fact, it occurs, on average, about every 32 months. And in the year 1999 it actually occurred twice in three months.

Re:Rare?

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.

Re:Rare?

Here [com.com] is a really good explanation of the background on our current definition of a "Blue Moon" which seems to have been popularized by none other than Trivial Persuit.

On July 31 of this year, those taking an evening stroll beneath a cloudless sky will have the opportunity to look up and see what modern folklore refers to as a "blue moon." Though the moon itself will not actually be blue--or likely even appear blue--it will be the second full moon in the same calendar month of July, which is what qualifies this Saturday's lunar view as a blue moon, at least by today's standards.

That's not to say that the moon has never appeared blue in color to the average, unaided, ground-bound observer. The moon can and has shone blue or even green in color whenever a sufficient quantity of micron-sized particulates is present in the atmosphere, usually after a volcanic eruption.

The micron-sized debris (specifically, any particles slightly larger than the wavelength of red light, about 0.7 microns) refracts the moonlight, turning it green or blue, based on certain atmospheric factors. For an example of this phenomenon, one need look no further than accounts of blue moons following the eruption of the island of Krakatau in 1883.

While instances of actual blue-tinted moons represent one of several documented meanings of the term, using blue moon to describe the second full moon in one calendar month is a fairly recent practice. This definition arose in the 20th century, and it didn't really become part of the widespread public consciousness until the 1980s.

We can attribute this sudden proliferation of a previously undocumented and unused definition for blue moon to three otherwise reputable sources of fine information and fun trivia, all of which were working off bad information.

WHAT THREE MASS-MEDIA TRIVIA SOURCES ARE MOST RESPONSIBLE FOR THE NEWEST DEFINITION OF A "BLUE MOON"?

What three reputable mass-media trivia resources are most responsible for the current popular definition of a "blue moon" to mean the second full moon in the same calendar month, and what is the likely origin of this "mistaken" definition?

The most recent and most widely known source of the "new" blue moon definition is none other than the king daddy of all trivia board games, Trivial Pursuit. Specifically, the Trivial Pursuit Genus II edition published in 1986 included this definition as a question in the Science and Nature category.

Given the popularity of the game, it's little wonder that folklorists witnessed this definition enter widespread usage in the 1980s. But where did the game makers get their information?

Trivial Pursuit archives (yes, they exist) cite The Kids' World Almanac of Records and Facts, published in 1985, as the source of the question. The book's authors, however, can't trace their own source for this "fact."

So where did the Almanac authors get it? Folklorist Philip Hiscock suggests it came from our second mass-media source.

In January 1980, the National Public Radio (NPR) program "Star Date" featured a piece by Deborah Byrd that noted the "second full moon in one calendar month" definition of blue moon. Byrd cited a 1946 article in Sky & Telescope magazine as her source. Hiscock considers the "Star Date" broadcast as the likely source of the Almanac entry, and thus NPR is the second mass-media source to get blue moon "wrong."

The third, obviously, is the usually reliable Sky & Telescope magazine. A March 1946 article by amateur astronomer James Hugh Pruett titled "Once in a Blue Moon" contains the modern definition of the term, but it cites the 1937 Maine Farmers' Almanac as its source. No edition of that Almanac, however, contains the modern definition of a blue moon.

Several editions of the Almanac do list a different definition of a blue moon--the third, extra full moon of an agricultural season. The Maine Farmers' Almanacs of tha

Re:Rare?

Sky and Telescope has published an article more recently, explaining what happened and their role in it. It is available online [skyandtelescope.com].

Blue, where is that coming from?

This looked weird, so I googled it. http://www.griffithobs.org/IPSBlueMoon.html I wonder if I'll be able to see it given the fact that i am in Scotland an clouds are everywhere.

This occured just 90 days after...

...the moon switched over to Windows ME. Even that stupid asteroid from Armageddon knows not to run ME.

Once in a Blue Moon

Neat! Maybe that means my askslashdot submission will be accepted!

two full moons not originally "blue moon"

A "blue moon" is not when there are two full moons in a month. It is when the moon actually turns a shade of blue.

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.

Rare?

We see a full moon every 28 days. So a month with 31 days will have a blue moon if it has a full moon in the first three days. The chance of that is 3/28. The chance of a blue moon in a 30-day month is 2/28. There are 7 31-day months, 4 30-day months. So chance of no blue moon in a year (treating the months as independent of each other which obviously isn't the case but shouldn't affect the outcome) is (25/28)^7 * (26/28)^4 which is about 43.4%. So there's a 56.6% chance of a blue moon in any year.

Re:Rare?

(treating the months as independent of each other which obviously isn't the case but shouldn't affect the outcome)

It is not the case, it should affect the outcome, and it does. Using your figures and ignoring fractional days of a lunation, the day of the month on which a full moon occurs regresses 1-3 days each month, so if a "blue" moon occurs this month (in days 29-31) one can't occur next month (in days 26-28).

Dark Side

I would have destroyed the world by now but my fricken incompetent evil empire but my "laser" on the Dark Side of the moon.

The Marcels

Blue Moon, you saw me standing alone
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

Very very rare

It occurs slightly less often than IE is patched.

How rare?

"A rare spectacle" that happens more often than U.S. Presidential elections. I guess that makes the elections a rarer spectacle.

Canceling out?

I wonder if the blue effect of ash and smoke would cancel out the yellowish hue of the moon when it's behind thin clouds to produce a somewhat greyscale moon, even when viewed in not-so-perfect weather. (As in color temperature)

interesting article about it in sky & telescop

see article [skyandtelescope.com]

From the article:

According to Canadian folklorist Philip Hiscock, the term "blue Moon" has been around for more than 400 years, but its modern calendrical meaning has become widespread only in the last 25. And as discovered five years ago, it can be traced to a mistake published in Sky & Telescope in the 1940s!

Black Moon is even more rare

When no full moons occur in a month (usually February).

Re:Black Moon is even more rare

"Black Moon is even more rare: When no full moons occur in a month (usually February)"

That would make it 2018 then?

Blue moon: 31/Jan/2008, 9am
Worm moon: 01/Mar/2008, 10pm

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...)

Blue moon explained

The term blue moon actually comes from the fact that in old almanacs the second full moon in a month was colored blue on the calendar.

Not Blue and Not Really a Blue Moon

According to an article on the Cincinnati Enquirer today (http://www.enquirer.com/editions/2004/07/31/loc_b luemoon31.html)

"Only once in a blue moon is there controversy over exactly what constitutes a blue moon. But it's not a blue moon in the strict definition of the 19th Century Farmer's Almanac. According to the almanac, a true blue moon is the third full moon in a season that has four full moons. This also happens about every three years, but on a different cycle from the blue moon that occurs tonight. Confused? So is the American Heritage Dictionary, which lists both definitions of the blue moon."

More in the article. Interesting Stuff

Blue mooning

This type of blue moon [chicago-orienteering.org] is rare unless beer is involved.

I swear I'm not making this up

...I read the article, and casually mentioned to the wife that tonight was a blue moon. She looked at me, and said with a straight face, "So, does that mean we have to have sex tonight?"

Re:I swear I'm not making this up

That reminds me, in a roundabout way, of one of my favorite jokes. A college psychology professor decides to quiz his students on their sexual habits. He asks the class how many have had sex more than once in the past week? Several raise their hands. How about once in the past week? More hands go up. Once in the past two weeks? And so on ... after he has gotten to once every two months, he notices that everyone in the classroom has raised his or her hand, except for one guy sitting in the back. So he goes on:

"Three months". Nothing.

"Four months". Nope.

"Six months". Still nothing.

"One year?!".

Finally the guy in the back practically leaps out of his chair, raising his hand up high and bouncing up and down enthusiatically. The prof acknowledges him, and asks, "Well if you only get it once a year, why are you so happy?". The geeky guy smiles and says:

"'Cause tonight's the night!!"

P.S. If your wife wears glasses, may I recommend blue filters? :)

Ding ga dong ding...

Aaarrggghhh...where are the Marcells when I need them!

Tim

P.S. The lyrics to that song (http://www.lyricsfind.com/m/marcels/best-of/blue- moon.php [lyricsfind.com]) sound like they could've been written by a /. reader. Well, except for the second verse.

Ske & Telescope had an article about this...

See the Sky & Telescope article: "What's a Blue Moon? The trendy definition of "blue Moon" as the second full Moon in a month is a mistake." http://skyandtelescope.com/observing/objects/moon/ article_127_1.asp

Science?

This falls under science? This is solely an artifact of our time measuring system. The moon is full every 28 days, but months are slightly longer than that. If a full moon is early enough in the month, it will be full twice.

A new Smurf will be born tonight!

Isn't a Smurf born once every blue moon [progressiveboink.com]?

Mead moon and Nanci Griffith

Related:

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].

I wonder how it affects global tides?

It would be interesting if someone "in the know" could share any insight on what effect (if any) these "extra" full moons have on tides.

Re:I wonder how it affects global tides?

None: The earth doesn't rely on a calendar so no pattern is changing.

So what?

This is just a calendar coincidence not any kind of astronomical event. And in fact it happens quite often. So really, there is nothing special to see here. Was that really worth mentioning on slashdot?

Weird ring around the moon

We've just got home from a night out, and we noticed that there is a big ring around the moon (at least from here in Melbourne) - very strange. If I was sober I would google this interesting phenomenon - can someone just tell me what it is instead?

picture of actual BLUE moon

On APOD there a picture [nasa.gov] of a moon that's really blue.

Once in a blue moon

"Sara, please cancel all my appointments; I'll be spending the day compiling E17 final and playing Duke Nukem Forever....."

-Chris

Still a chance for a `true' blue moon ...

This whole `second full moon in a month' thing is just stupid. Looks like there's already some interesting comments here about the original source of this idea.

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.

Woohoo

I'm gonna get laid!

Shameless plug

for my website www.bluemoonbikes.com

If you like classic 70's Stingrays or other classic chopper bicycles, check it out!

Do it today and feel extra special!

Great

Finally, SP2 will make Windows a stable, secure and robust operating system...

What's that? Oh, I thought you said cows will be jumping over the moon. Wrong moon reference, sorry..

Admire it while it lasts....

This type of thing happens only once in a blue moon.

Blue photo at Astronomy Picture of the Day

See also a pretty photo [nasa.gov], along with some explanations of the term "blue moon".

Moon Phase indicator for KDE is pretty cool...

I have it running in the System Tray, where it shows an icon version of the moon phase. Comes with the KDE desktop in Gentoo, located under "Toys".

Written by Stephan Kulow.

Blue Moon

Clearly this is "moon" you speak of is simply nothing more than IBM's newest supercomputer. The question is...can it play chess?

Don't need dupes anymore...

I guess this is the new /. alternative to dupes... posting about periodic, anticipated events that happen multiple times a year. :-)

In this new category: IE exploits, IE patches, Firefox point-point releases, and PHP flamewars. I'm sure there's plenty of other things that can belong in this category...

This is wrong on so many levels

Most of the mistakes, commentary, etc. have been captured by previous posters (see notes on APOD picture, Sky and Telescope explaining their mistake that led to the popularization of the mistaken "two full moons in a month" idea, etc. But one problem with the original article remains to be fixed: Atmospheric scattering tends to make light from the Sun, moon etc. red not blue, if due to macroscopic particles, or just to wash out the sky color if due to water vapor, etc. The sky is blue under good conditions because you are viewing the off-angle scattering AWAY from the original light direction, strongly related to why sunsets are red (the blue light has been scattered out, most noticeable when the object shining the light is at the horizon and the light thus traverses the most atmosphere to reach you). Sigh...

Let's not forget...

...that blue moons are also when new Smurfs are born! (Anyone else remember Baby Smurf?) The series went downhill after that; just like Growing Pains and Family Ties when they added a baby.

Boy am I sleepy.

Not for everyone tonight

Those of us on the other side of the dateline won't get our blue moon till the end of August. The full moon didn't officially happen until our August 1st (your July 31st), but luckily it all washes out in the end.

why it is called blue

I heard about 2 years ago that the word blue comes from the early thought that the moon is made of cheese, and therefore it got the its name from the type of cheese it was beleived to be: bleu.

For some of us, it's next month...

The full moon occurs at 4am Sunday morning here in Australia, meaning that for us, the blue moon occurs next month.

Moo

This is hilarious. The idea that a month has to do with moons goes back to calenders that were moon based (Muslim Calender, and Jewish calender is partially). On them, there is exactly one full moon per month, being "full" on the fifteenth (or fourteenth, on the now one-day-off Jewish calender).

The Gregorian and Julian calenders are solar based, however, being they have 31 days in some months, it is possible to have to full moon on both the first and 31st day of the month. That this is a rare occurence, is possibly worth noting, but this much atention seem absurd.

Re:Global Warming...

Yes, not only will global warming cause the seas to rise, polar caps, to melt, cause general destruction to the whole planet...

It will cause the moon to obit the earth faster and produce more full moons.

Congrats, you may be the dumbest person ever on slashdot. And believe me, that's saying something.

Re:Global Warming...

In that case, we can thank the sun [bbc.co.uk] for all the blue moons:

BBC: Sunspots reaching 1,000-year high
A new analysis shows that the Sun is more active now than it has been at anytime in the previous 1,000 years.

Scientists based at the Institute for Astronomy in Zurich used ice cores from Greenland to construct a picture of our star's activity in the past.

They say that over the last century the number of sunspots rose at the same time that the Earth's climate became steadily warmer.