- WASHINGTON (Reuters) - The
most spectacular Leonid meteor storm in 35 years is forecast for Sunday
in the Americas and Monday in Asia and Australia as Earth passes near centuries-old
debris left by comet Tempel-Tuttle.
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- The celestial storm could affect some satellites orbiting
close to earth, so NASA scientists are making sure their spacecraft stay
out of harm's way.
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- Leonid meteors -- so called because they appear to come
from the same part of the sky as the constellation Leo -- fall to Earth
each November, but this year's show should be especially dramatic, with
some 30 shooting stars streaking across the American sky each minute at
the storm's height and perhaps 100 a minute over eastern Asia and Australia.
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- During a normal year, Earth encounters some 10-15 Leonid
meteors an hour at best.
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- This year is special because Earth will travel close
to three paths of cosmic dust and debris left by comet Tempel-Tuttle's
previous trips around the sun.
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- The comet orbits the sun every 33.25 years and takes
a slightly different path each time; on Sunday and Monday Earth will swing
near to dust trails left in 1699, 1767 and 1866, according to the American
Meteor Society.
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- Observers in extreme northwestern South America, Central
America and North America are likely to see meteors shooting across the
heavens around 5 a.m. EST (1000 GMT), when Earth gets near dust trail left
by the 1767 encounter.
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- Those in eastern Asia and Australia have two chances
for good viewing, with the first meteoric outburst, spawned by the 1699
debris trail, expected around 12:30 p.m. (1730 GMT) Sunday, or 1:30 a.m.
on Monday in Korea and 4:30 a.m. in eastern Australia.
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- METEOR-GAZING PARTIES
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- The 1866 debris path could send meteors streaming aloft
just 45 minutes later for Asian and Australian observers.
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- The American Meteor Society gives tips on best observing
times and conditions on its Web site, www.amsmeteors.org.
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- Meteor-watching parties are planned from New York state
to California to Hawaii and other events are slated for Taiwan and Australia,
according to the National Aeronautics and Space Administration site, www.leonid.arc.nasa.gov.
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- At NASA's Goddard Space Flight Center, where astronomers
work with many orbiting spacecraft, including the Hubble Space Telescope,
Bob Sodano is charged with cutting down the risk the Leonids pose.
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- Most Leonid meteors are about the size of a grain of
salt and vaporize high in the atmosphere, posing no threat to anything
on earth or even to aircraft, Sodano said in a telephone interview.
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- But though they are small, they are exceedingly fast,
moving at 44 miles per second, and impact with a Leonid might affect might
affect computers or power sources on satellites in low-earth orbit, Sodano
said.
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- This high speed means Leonids vaporize on impact, forming
a cloud of electrified gas called plasma, and this cloud might cause a
short circuit in a satellite, possibly damaging some of its electrical
components.
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- Sodano said the 20 or so NASA spacecraft at risk during
the storm will be pointed away from the direction of the Leonid stream,
and high-voltage components will be turned down.
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