Wednesday, November 11, 2009


The 2009 Leonid Meteor Shower

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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

see caption

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!
The first stream crossing on Nov. 17th comes around 
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.
see caption
Above: This side of Earth will be facing the Leonid debris 
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 
Environment Office.
"Even if rates are only half that number, it would still be 
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


Laura in Paris said...

THank you for this instructive post! Didn;t know anything about this meteor shower!
I'd like you to check my blog, I have awarded you the Honest Scarp Award - and start thinking what ten truths you're going to tell!

RoyalTLady said...

Neither did I know about this shower.
I have just read it. But I hope it's useful to others...

Thanks for the award BUT please excuse me... I am going to be late in responding.... my thinking cap is missing... together with my cam... sob, sob, sob.

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