Blue moons are when you get two of them in the same month and it's supposed
to be rare. At least that's what the weather person said on the
news. We aren't supposed to have another one for years.
Stacy
"True happiness lies not in everything you want, but rather enjoying
everything you have"
----- Original Message -----
Sent: Saturday, July 31, 2004 3:46
PM
Subject: [QUAD-L] Blue Moon
Tonight!
Howdy folks,
Prepare to be mooned--blue mooned. This
Saturday, July 31, a "blue moon"
rises. Of course, you probably won't see
even a hint of blue color, just
your average full moon. So what gives?
What's so blue about a moon that
isn't? Heck, astronomers even say that
blue moons aren't rare. And
folklorists say they're not what everyone
thinks they are.
* * * * * * * * * * * *
Today's Knowledge Blue
Moons That Are (and Blue Moons That Aren't)
As any budding astronomer
can tell you, a "blue moon" is the second full
moon in a calendar month.
It isn't really blue. It's just a name. But why,
of all things, do we call
a white moon "blue"?
The First Recorded Blue Moon
Actually,
there are truly blue moons. In 1883, an Indonesian volcano
erupted with
the force of a 100-megaton nuclear bomb. With a roar heard
nearly 400
miles (over 600 kilometers) away, Mount Krakatoa belched a
column of
volcanic gas and ash into the atmosphere. That night, the moon
rose blue
over Indonesia.
Particles from Krakatoa's ash, not more than a micron
wide, made it happen.
These micron-wide particles were exactly the right
size to scatter red
light, while allowing other colors, such as blue, to
pass. The result: a
blue sphere hanging in the sky. Different sized
particles filtered other
colors and caused different effects.
In
fact, for several years after the eruption, there were reports from all
over the globe of red moons, green moons, and, yes, even more blue moons.
What's more, some of the sunsets following the eruption were such a
blazing
red that people actually called on firemen to drown the optical
illusion.
The eruptions of Mount St. Helens and Mount Pinatubo produced
the same
anomaly. So have forest fires.
Changing Hue
Still,
none of this explains why we call the second full moon in a month a
blue
moon. The phrase is old, even if the modern meaning is not. Before
Shakespeare penned a word of Hamlet, the English knew little couplets
like:
If they say the moon is blewe, We must believe that it is true.
Eventually,
a 19th-century almanac put this metaphorical moon in the sky.
According to
the Maine Farmers' Almanac, a blue moon occurred whenever a
season had four
full moons instead of three. It was common to give moons
seasonal names
during this time, so you had harvest moons, fruit moons,
and egg moons, too.
Follow That Moon
It didn't stop there. In
1946, Sky & Telescope magazine published an
article that
misinterpreted the Maine almanac's seasonal definition, making
the blue
moon the second full moon in a month instead of the fourth full
moon in a
season. The magazine soon adopted this new meaning. (They 'fessed
up to
their mistake in 1999.)
It took the modern media machine, however, to
put blue moons on the tip of
everyone's tongue. Starting in 1986, the
Genus II edition of Trivial
Pursuit told a whole generation of trivia
buffs that blue moons were the
second full moon in a calendar month. Their
source? A 1985 children's book,
Facts and Records. Its source? No one
knows.
In 1999, the blue moon's fate was sealed through extraordinary
lunar
happenings. There were two full moons in January and March and none
at all
in February. The media had a field day, talking over and over about
the
"blue moons" of January and March. It was blue moon mania. The new
definition stuck. Sure, the blue moon was no longer blue, and a long way
from its Indonesian home. But transformations like that can occur--once in
a blue moon.
Will Bilbrey July 29, 2004
Want to learn more?
Look at a moon map
http://nssdc.gsfc.nasa.gov/planetary/
lunar/moon_landing_map.jpg
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