| The 2009 Leonid Meteor Shower ||11.10.2009 |
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November 10, 2009: This year's Leonid meteor shower
peaks on Tuesday, Nov. 17th. If forecasters are correct,
the shower should produce a mild but pretty sprinkling of
meteors over North America followed by a more intense
outburst over Asia. The phase of the Moon will be new,
setting the stage for what could be one of the best Leonid
showers in years.
"We're predicting 20 to 30 meteors per hour over the
Americas, and as many as 200 to 300 per hour over Asia,"
says Bill Cooke of NASA's Meteoroid Environment Office.
"Our forecast is in good accord with independent theoretical
work by other astronomers."1
Right: A Leonid meteor at dawn, photographed in 2002
by Simon Filiatrault of Quebec, Canada. [larger image]Leonids are bits of debris from Comet Tempel-Tuttle.
Every 33 years the comet visits the inner solar system
and leaves a stream of dusty debris in its wake. Many
of these streams have drifted across the November portion
of Earth's orbit. Whenever we hit one, meteors
come flying out of the constellation Leo.
"We can predict when Earth will cross a debris stream
with pretty good accuracy," says Cooke. "The intensity of
the display is less certain, though, because we don't know
how much debris is in each stream." Caveat observer!
0900 UT (4 a.m. EST, 1 a.m. PST). The debris is a diffuse
mix of particles from several old streams that should produce
a gentle display of two to three dozen meteors per hour
over North America. Dark skies are recommended for full
effect. "A remarkable feature of this year's shower is that
Leonids will appear to be shooting almost directly
out of the planet Mars," notes Cooke.
It's just a coincidence. This year, Mars happens to be
passing by the Leonid radiant at the time of the shower.
The Red Planet is almost twice as bright as a first magnitude
star, so it makes an eye-catching companion for the Leonids:
sky map.The next stream crossing straddles the hour
2100-2200 UT, shortly before dawn in Indonesia and China.
At that time, Earth will pass through a pair of streams laid
down by Comet Tempel-Tuttle in 1466 and 1533 AD. The
double crossing could yield as many as 300 Leonids per hour.
Above: This side of Earth will be facing the Leonid debris"Even if rates are only half that number, it would still be
stream at the time of the Nov. 17th outburst. Observers in
India, China and Indonesia are favored with dark, pre-dawn
skies. Image credit: Danielle Moser of the NASA Meteoroid
one of the best showers of the year," says Cooke.
The Leonids are famous for storming, most recently in
1999-2002 when deep crossings of Tempel-Tuttle's debris
streams produced outbursts of more than 1000 meteors
per hour. The Leonids of 2009 won't be like that, but it
only takes one bright Leonid streaking past Mars to make
the night worthwhile.
Enjoy the show.
Author: Dr. Tony Phillips | Credit: Science@NASA