The 2008 Perseid Meteor Shower
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http://science.nasa.gov/h...008/22jul_perseiddawn.htm
 Mark
your calendar: The 2008 Perseid meteor shower peaks
on August 12th and it should be a good show. "The time
to look is during the dark hours before dawn on Tuesday,
August 12th," says Bill Cooke of NASA's Meteoroid
Environment Office at the Marshall Space Flight Center.
"There should be plenty of meteors--perhaps one or two
every minute."
The source of the shower is Comet Swift-Tuttle. Although
the comet is far away, currently located beyond the
orbit of Uranus, a trail of debris from the comet
stretches all the way back to Earth. Crossing the trail
in August, Earth will be pelted by specks of comet dust
hitting the atmosphere at 132,000 mph. At that speed,
even a flimsy speck of dust makes a vivid streak of
light when it disintegrates--a meteor! Because,
Swift-Tuttle's meteors streak out of the constellation
Perseus, they are called "Perseids."
(Note: In the narrative that follows, all times are
local. For instance, 9:00 pm means 9:00 pm in your time
zone, where you live. )
Serious meteor hunters will
begin their watch early, on Monday evening, August 11th,
around 9 pm when Perseus first rises in the northeast.
This is the time to look for Perseid Earthgrazers--meteors
that approach from the horizon and skim the atmosphere
overhead like a stone skipping across the surface of a
pond.
"Earthgrazers are long, slow and colorful; they are
among the most beautiful of meteors," says Cooke. He
cautions that an hour of watching may net only a few of
these at most, but seeing even one can make the whole
night worthwhile.
A warm summer night. Bright meteors skipping overhead.
And the peak is yet to come. What could be better?
The answer lies halfway up the southern sky: Jupiter and
the gibbous Moon converge on August 11th and 12th for a
close encounter in the constellation Sagittarius: sky
map. It's a grand sight visible even from light-polluted
cities.
For a while the beautiful Moon will interfere with the
Perseids, lunar glare wiping out all but the brightest
meteors. Yin-yang. The situation reverses itself at 2 am
on Tuesday morning, August 12th, when the Moon sets and
leaves behind a dark sky for the Perseids. The shower
will surge into the darkness, peppering the sky with
dozens and perhaps hundreds of meteors until dawn.
Above: The eastern sky viewed during the hours before
sunrise on Tuesday, Aug. 12, 2008.
For maximum effect, "get away from city lights," Cooke
advises. The brightest Perseids can be seen from cities,
he allows, but the greater flurry of faint, delicate
meteors is visible only from the countryside. (Scouts,
this is a good time to go camping.)
The Perseids are coming. Enjoy the show!
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