Dear friends of Science, Astronomy and Astrophysics,

From: kutchsciencefoundation@...







http://science.nasa.gov/headlines/y2009/10aug_horseflies.htm

Horse Flies and Meteors

Like bugs streaking down the side window of a moving car, long and
colorful Perseid Earthgrazers could put on a remarkable show before midnight on
August 11th.





August 10, 2009:Â Splat! There goes another bug on the
windshield.
Anyone who's ever driven down a country lane has seen it happen. A fast
moving car, a cloud of multiplying insects, and a big disgusting
mess.
The next time that happens to you, instead of
grossing out, try thinking of the experience as an astronomy lesson. Your car is
Earth. The bugs are tiny flakes of comet dust. The carnage on your windshield
... it's a meteor shower!
Right:Â A
fiery meteor? No. It's a horse fly. From "That Gunk on your Car: A Unique Guide
to Insects of North America," by Mark E. Hostetler.
Earth, like a speeding car, races around the Sun sweeping up everything
in its path. There are no insects in space, at least none that we know of, but
there are plenty of meteoroids, little flakes of dust from comets and asteroids.
They hit Earth's atmosphere and--splat!--they disintegrate as fiery streaks of
light called meteors.
This week lots of meteors will appear over Earth's northern hemisphere
when our planet plows through a swarm of dust shed by periodic comet
Swift-Tuttle. It's the annualPerseid
meteor shower, which peaks on August 11th and 12th.

Just as bugs tend to accumulate on the
front windshield of a car, Perseids accumulate on the front windshield of
Earth.
Earth has a windshield? It's the atmosphere, which protects us from solar
wind and comet dust much as a car's windshield protects passengers from wind,
rain and bugs. Earth's front windshield is the early morning sky. Earth circles
the Sun dawn-side first, scooping up whatever lies on that side of the planet.
That's why it's usually best to look for Perseids just before dawn.
A good time to see Perseids this year is before dawn on Wednesday
morning, August 12th, when Earth's front windshield is overhead. You could see
dozens of meteors despite the glare of a 66% gibbous Moon.
Side windows, the ones to the left and right of passengers in cars, are
good, too. Zooming down a bug-infested lane, side windows don't intercept many
insects, but the ones they do gather are worth examining. Bugs that strike side
windows do so at a shallow angle, leaving long and colorful streaks.

Above:Â A Perseid meteor. Credit: S.
Kohle & B. Koch.
This also happens to meteors. When the constellation Perseus (the source
of the Perseids) hangs low near the horizon, meteors streaming from Perseus will
skim the the top of Earth's atmosphere, much like a bug skimming the side window
of an automobile. Astronomers call these meteors "Earthgrazers." They tend to be
long and colorful.
Look for Perseid Earthgrazers on Tuesday night, Aug. 11th,
between about 9:00 and 11:00 pm local time.
Earthgrazers don't come in large numbers. The special geometry required
to produce them keeps counts low, but even one or two is enough. A breathtaking
Earthgrazer is the sort of meteor you're likely to remember for
years.


Forwarded By kutchsciencefoundation@...







With
Compliments from: Dr.
BHUDIA : Science Group Of INDIA.
http://uk.groups.yahoo.com/group/venustransit_2004/
President:"Kutch Science
Foundation".
Founder :"Kutch Amateurs Astronomers Club -
Bhuj - Kutch".
Life Member:"kutch Itihaas
Parishad".
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