Aeronautics Industry

Guest · Posted: Wed May 30, 2007 10:20 pm Post subject: Blue Moon over North America

http://science.nasa.gov/headlines/y2007/30may_bluemoon.htm

Blue Moon over North America
NASA Science News
May 30, 2007

May 30, 2007: At 9:04 pm Eastern Daylight Time on May 31st, the full
moon over North America will turn blue.

Not really. But it will be the second full moon of May and, according
to
folklore, that makes it a Blue Moon.

If you told a person in Shakespeare's day that something happens "once
in a Blue Moon" they would attach no astronomical meaning to the
statement. Blue moon simply meant rare or absurd, like making a date
for
"the Twelfth of Never."

But "meaning is a slippery substance," writes
Philip Hiscock of the Dept. of Folklore, Memorial University of
Newfoundland. "The phrase 'Blue Moon' has been around a long time,
well
over 400 years, and during that time its meaning has shifted."

The modern definition sprang up in the 1940s. In those days the Maine
Farmer's Almanac offered a definition of Blue Moon so convoluted even
professional astronomers struggled to understand it. It involved
factors
such as ecclesiastical dates of Easter and Lent, tropical years, and
the
timing of seasons according to the dynamical mean sun. Aiming to
explain
blue moons to the layman, Sky & Telescope published an article in 1946
entitled "Once in a Blue Moon." The author James Hugh Pruett
(1886-1955)
cited the 1937 Maine almanac and opined that the "second [full moon]
in
a month, so I interpret it, is called Blue Moon."

This was not correct, but at least it could be understood. And thus
the
modern Blue Moon was born. A detailed account of the story may be
found
here <http://skytonight.com/observing/objects/moon/3304131.html>.

Surveying the last four centuries of literature and folklore, "I have
counted six different meanings which have been carried by the term,"
recounts Hiscock. In song, for instance, Blue Moons are a symbol of
loneliness; when love conquers all, the Blue Moon turns gold. (See old
Elvis records for more information.) "This makes discussion of the
term
a little complicated," he says.

One complication is that the Moon can turn genuinely blue, as shown in
this photo taken by Tom King of Watauga, Texas:

http://science.nasa.gov/headlines/y2007/images/bluemoon/King2.jpg

Above: A blue Moon photographed in October 2003 by Tom King of
Watauga,
Texas. "Here is a picture <images/bluemoon/King_gray.jpg> from a
different night provided as a sanity check to assure you that my moon
shots do not always have this blue hue," says King.

"I had never paid any real attention to the term 'Blue Moon' until one
October evening in 2003," he recalls. "I had my telescope set up in
the
backyard and the moon began rising in the east with a strange blue
tint
I had not seen before."

The cause of the blue was probably tiny droplets of water in the air.
"The air was damp and heavy with moisture," notes King. When water
droplets are about 1 micron (one millionth of a meter) in diameter,
they
strongly scatter red and green light while allowing other colors to
pass. A white moonbeam passing through such a misty cloud turns blue.

Clouds of ice crystals, fine-grained sand, volcanic ash or smoke from
forest fires can have the same effect. "The key," notes atmospheric
optics expert Les Cowley, "is that the airborne particles should all
be
of very similar size, a micron or so in diameter." Only then do they
scatter the correct wavelengths of moonlight and act as a blue filter.

There are other reasons for blue Moons, he notes. "Our eyes have
automatic 'white balances' just like digital cameras. Go outdoors from
a
cozy cabin lit by an oil lamp (yellow light) and the Moon will appear
blue until your eyes adjust."

What kind of Blue Moon will you see this week? There's only one way to
find out!

N:dlzc D:aol T:com (dlzc) · Guest

Dear baalke:

<baalke@earthlink.net> wrote in message
news:1180549246.325660.188480@g37g2000prf.googlegroups.com...

Llanzlan Klazmon the 15th · Guest

"N:dlzc D:aol T:com $dlzc$" <dlzc@aol.com> wrote in news:DPo7i.343440
$7g3.201895@newsfe14.phx:

Greg D. Moore (Strider) · Guest

"N:dlzc D:aol T:com (dlzc)" <dlzc@aol.com> wrote in message
news:DPo7i.343440$7g3.201895@newsfe14.phx...