----- Original Message -----
From: "Ron Baalke" <info@...>
To: <mok14@...>
Sent: Friday, October 10, 2003 6:15 PM
Subject: The 2003 Leonid Meteor Shower


> http://science.nasa.gov/headlines/y2003/10oct_doubleleonids.htm
>
> The 2003 Leonid Meteor Shower
> NASA Science News
> October 10, 2003
>
> An unusual double Leonid meteor shower is going to peak next
> onth over parts of Asia and North America.
>
> The Leonid meteor shower is coming. Twice.
>
> Bill Cooke of the Space Environments Group at the NASA Marshall Space
> Flight Center explains: "Normally there's just one Leonid meteor shower
> each year, but this year we're going to have two: one on Nov. 13th and
> another on Nov. 19th."
>
> Both are caused by comet Tempel-Tuttle, which swings through the inner
> solar system every 33 years. With each visit the comet leaves behind a
> trail of dusty debris--the stuff of meteor showers. Lots of the comet's
> old dusty trails litter the mid-November part of Earth's orbit.
>
> "Our planet glides through the debris zone every
> year," says Cooke. "It's like a minefield.
> Sometimes we hit a dust trail, sometimes we don't."
> Direct hits can spark a meteor storm, which is
> defined as more than 1000 shooting stars per hour.
> "That's what happened in, for example, 1966 and
> 2001," says Cooke. "Those were great years for
> Leonids."
>
> "This year we're going to brush past two of the trails--no direct hits,"
> he says. Even so, "we might have a nice display."
>
> The first shower is expected on Nov. 13th around 17:17 UT. For about
> three hours centered on that time Earth will be close to some dust shed
> by Tempel-Tuttle in the year 1499. Sky watchers in Alaska, Hawaii and
> along the Pacific rim of Asia are favored. They'll see anywhere from a
> few to 40 meteors per hour--"if they can avoid the glare from that
> night's gibbous Moon," cautions Cooke. A good strategy for moonlit meteor
> observing: travel to high altitudes where the air is clear or stand in
> the shade of a tall building or hillside.
>
> Leonid meteor rates for selected cities: Nov. 13-14, 2003
>
> City Local Time Maximum number of
> Leonids in 15 min.
>
> Los Angeles, CA 5:15 a.m. (Nov. < 3
> 13th)
>
> Seattle, WA 5:45 a.m. (Nov. 3
> 13th)
>
> Fairbanks, AK 7:00 a.m. (Nov. 10
> 13th)
>
> Honolulu, HI 5:30 a.m. (Nov. 9
> 13th)
>
> Tahiti 5:00 a.m. (Nov. 6
> 13th)
>
> Tokyo, Japan 2:30 a.m. (Nov. 18
> 14th)
> Christchurch, New 3:30 a.m. (Nov.
> Zealand 14th) 1
>
> Sydney, Australia 3:30 a.m. (Nov. 9
> 14th)
>
> Hong Kong 2:00 a.m. (Nov. 8
> 14th)
>
> Beijing, China 1:45 a.m. (Nov. 10
> 14th)
> Manila, the 1:45 a.m. (Nov.
> Philippines 14th) 9
>
> Table notes: Values listed in the 3rd column are the maximum number of
> meteors an observer with perfectly clear dark skies might see in a
> 15-min. interval.
>
> Curiously the Moon will be much closer to the 1499 trail than Earth will
> be. "If the Moon had an atmosphere to catch the comet dust, there would
> be about 1400 meteors per hour in lunar skies--a real storm," notes
> Cooke. Instead, the Leonids will simply hit the ground.
>
> Most Leonid meteoroids are microscopic, and when they hit the Moon they
> do little more than raise a puff of moon dust. But a few will be bigger:
> the size of golf balls or grapefruits. Traveling about 160,000 mph, these
> impactors can cause explosions visible from Earth. (For more information
> about this, read the Science@NASA story Explosions on the Moon.)
>
> "This year we won't be able to see any lunar impacts," notes Cooke,
> "because most of the Leonids will strike the far side of the Moon. Some
> will hit the Earth-facing side, but the ground where they hit will be
> sunlit. That makes it very hard to see the explosions."
>
> The second and more impressive shower arrives almost a week later on Nov.
> 19th when Earth approaches a trail shed in 1533. "Sky watchers up and
> down the US east coast will have the best view," says Cooke. "For a while
> around 07:28 UT (2:28 a.m. EST), they could see more than one meteor per
> minute." The Moon, a thin crescent on Nov. 19th, won't be bright enough
> to interfere with the display. (Nor will it be close to the cometary dust
> stream, so once again there will be no visible lunar explosions.)
>
> Leonid meteor rates for selected cities: Nov. 19, 2003
>
> City Local Time Maximum number of
> Leonids in 15 min.
>
> New York, NY 2:30 a.m. (Nov. 17
> 19th)
>
> Miami, FL 2:30 a.m. (Nov. 14
> 19th)
>
> Chicago, IL 1:30 a.m. (Nov. 13
> 19th)
>
> Dallas, TX 1:45 a.m. (Nov. 9
> 19th)
>
> Denver, CO 0:45 a.m. (Nov. 7
> 19th)
>
> Los Angeles, CA 0:00 a.m. (Nov. 3
> 19th)
>
> Caracas, Venezuela 3:30 a.m. (Nov. 17
> 19th)
> San Juan, Puerto 3:30 a.m. (Nov.
> Rico 19th) 18
>
> Bermuda 3:30 a.m. (Nov. 19
> 19th)
>
> London, England 5:45 a.m. (Nov. 7
> 19th)
>
> Paris, France 6:30 a.m. (Nov. 6
> 19th)
>
> Cooke assembled these forecasts using data from several researchers who
> have done a good job predicting Leonid storms in recent years: Peter
> Jenniskens at NASA's Ames Research Center, Jeremy Vaubaillon of the
> Institut de Mecanique Celeste et de Calcul des Ephemerides in France, and
> Esko Lyytinen. They mostly agree that Earth will encounter dust streams
> on Nov. 13th and 19th, but there is less consensus about how intense the
> resulting showers will be. Lyytinen, for instance, predicts a maximum of
> just 30 meteors per hour on Nov. 19th. Vaubaillon says 100.
>
> Who's right? See for yourself. Be outside when the time comes, looking
> up.
>
>
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