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(meteorobs) "Leonid Meteor Shower Could Be One Of Best In History"; "Astronomers Anticipate Meteor 'Storm' On November 18th"
Apologies for this repost... The text was truncated in our Web archive, due to
heavy email volume on our server. (Imagine what NEXT weekend will be like!)
Lew Gramer
------- Forwarded Message
To: Meteor Observing Mailing List <meteorobs@atmob.org>
Cc: Ron Baalke <baalke@zagami.jpl.nasadot gov>
Subject: (meteorobs) "Leonid Meteor Shower Could Be One Of Best In History";
"Astronomers Anticipate Meteor 'Storm' On November 18th"
From: Lew Gramer <dedalus@alum.mitdot edu>
Here is some wonderful press on the upcoming Leonid meteor shower...
EDITOR'S NOTE: There is some concern that not ALL scientists actually
predict a storm visible over North America! Of course, we encourage all
interested members of the public to get out before dawn Sunday morning,
18 November. But keep in mind that the only CONSENSUS prediction right
now, is for a storm over Western Pacific / East Asia, 7-8 hours later.
Clear skies around the world that weekend!
Lew Gramer, North American Meteor Network
- ------- Forwarded Message #1
>From: Ron Baalke <baalke@zagami.jpl.nasadot gov>
Astronomical Society of the Pacific
San Francisco, California
November 1, 2001
Leonid Meteor Shower Could Be One Of Best In History
By Robert Naeye
In the wee morning hours of Sunday, November 18, the Leonid meteor shower
might intensify into a dazzling meteor storm, with "shooting stars"
continuously blazing trails across the night sky. Viewers across the
United States are perfectly positioned to take advantage of the storm,
which could be among the most spectacular sky events of the 21st century
according to the latest scientific predictions.
The peak in shower activity will occur between 4:00 and 6:00 a.m. EST, or
1:00 and 3:00 a.m. PST on Sunday morning, November 18. "During the peak,
people viewing under clear and dark skies could see meteors shooting
across the sky at a rate of 1,000 to 2,000 per hour, with flurries of one
meteor per second at the peak of the storm," says Robert Naeye, Editor of
Mercury magazine, which is published in San Francisco by the Astronomical
Society of the Pacific (ASP).
During the predicted storm, Earth will plow through a trail of tiny dust
particles left behind by Comet Tempel-Tuttle during its passage through
the inner solar system in the year 1767. This comet rounds the Sun every
33.25 years, shedding dust particles as it is warmed by sunlight. Meteor
showers occur when Earth passes through debris left behind by comets.
But meteor storms occur when Earth passes through particularly dense
ribbons of comet debris.
"During a typical Leonid meteor shower, an experienced observer might see
about 10 to 15 meteors per hour. But during a storm, that rate climbs to
1,000 or more meteors per hour," says Naeye. "This year's Leonid storm
might peak at a rate of up to 2,000 per hour, although it's difficult to
pin down a precise number. The rates will rise and fall over a period of
two hours."
"Of course, these numbers depend on the accuracy of our predictions. But
the predictions have been remarkably accurate in recent years," says ASP
member Dr. Peter Jenniskens, an astronomer and meteor researcher at the
SETI Institute in Mountain View, California, and author of an in-depth
article about meteor science in the November/December 2001 issue of
Mercury magazine.
This year's Leonid display has two added bonuses. The Moon will rise
during daylight and set six hours before the peak, so the Moon's glare
will not obscure fainter meteors. In addition, the peak will occur on
a Sunday morning, so many people can sleep in after a long night of
skygazing.
If one mentally traces back the trajectory of Leonid meteors, they
appear to originate in the constellation Leo (the Lion). Leo rises
around midnight, so the shower will be minimal in the hours immediately
after sunset. But it will pick up considerably as the night progresses.
The entire United States should enjoy a good shower. Peak meteor rates
should occur around 5:00 a.m. EST, 4:00 a.m. CST, 3:00 a.m. MST, and
2:00 a.m. PST. Observers in eastern Asia and the Western Pacific will
also enjoy a storm approximately 8 hours later (in the morning hours
of November 19, local time), according to the forecasts. For the
latest predictions for your local area, visit this website from NASA's
Ames Research Center
http://www-space.arc.nasadot gov/~leonid/estimator.html
Earth will encounter another dense ribbon of Comet Tempel-Tuttle debris
in 2002, but under a full Moon. After that, it's over for nearly a
century. "It's now or never," stresses Naeye. "People should take
advantage of this year's Leonid storm, because astronomers don't think
we'll see another storm like this one until the year 2099. We will
probably never see a better meteor shower in our lifetimes."
When you see meteors, popularly known as "shooting stars," you're seeing
interplanetary dust particles burning up in the atmosphere at altitudes
of about 60 to 70 miles. A typical comet dust particle -- known as a
meteoroid -- is only about the size of a grain of sand or a pebble when
it enters the atmosphere. Larger chunks of comet debris, perhaps up to
the sizes of basketballs, sometimes light up the sky as they burn up,
which are events called fireballs or bolides. Leonids enter the
atmosphere at 160,000 miles per hour, making them the fastest meteors
of the year.
"Shooting stars are for every man, woman, and child to see, and it
doesn't take any special equipment to see them," says Jane Houston Jones,
a member of the ASP Board of Directors and an experienced meteor observer.
"Most Leonid meteors are faint, so you'll see more of them if you are far
away from city light pollution. If you can't get to a dark site, then
control your own light pollution by turning out as many lights as you
can control. Then sit back in a lawn chair, bundle up in a blanket,
and at a little before midnight local time, face east. You'll see the
backwards question-mark shape of Leo's mane rising, and that's where the
meteors will appear to radiate over the next few hours."
Meteors are beautiful sky events for skygazers. But for scientists,
meteors are fascinating in their own right. "Meteor science involves more
than just predicting storms. We also want to learn about the meteoroids
themselves, which in turn tell us a great deal about the parent comet,"
says Jenniskens. "We also want to learn more how meteors may have brought
critical organic material to Earth, perhaps leading to the origin and
prevalence of life on our planet."
Related Articles:
* Ready for the Storm, by Peter Jenniskens
http://www.astrosociety.org/pubs/mercury/1101pr/leonids.html
* How to Enjoy the Meteor Show, by Jane Houston Jones
http://www.astrosociety.org/pubs/mercury/1101pr/leonidsidebar.html
- ------- Forwarded Message #2
>From: Ron Baalke <baalke@zagami.jpl.nasadot gov>
>Subject: Astronomers Anticipate Meteor 'Storm' On November 18th
>Date: Fri, 9 Nov 2001 11:15:24 -0800 (PST)
Sky & Telescope Magazine
For immediate release: November 8, 2001
ASTRONOMERS ANTICIPATE METEOR "STORM" ON NOVEMBER 18TH
Most everyone has glimpsed an occasional "shooting star," or meteor. But
imagine what it would be like to see hundreds -- or even thousands -- of
them in a single night. Such a spectacle may occur in the hours before
dawn on Sunday, November 18th. In fact, if astronomers' predictions hold
up, skywatchers in North America can expect to see their most dramatic
meteor display in 35 years. "Earth is about to plow through a cloud of
space dust that could light up our skies with celestial fireworks," notes
Alan MacRobert, senior editor for SKY & TELESCOPE magazine.
These meteors, called Leonids because they appear to radiate from the
constellation Leo (the Lion), will signal the arrival of fast-moving dust
particles shed by Comet Tempel-Tuttle, which loops around the Sun every
33 years. Like a truck on a dirt road, the comet creates a dusty wake
that spreads along its orbit. When Earth crosses that orbit in mid-
November each year, skywatchers usually see a handful of shooting stars,
a weak meteor "shower." But three times each century Earth crosses the
dust stream where it's especially dense, and when that happens we
experience what astronomers call a meteor "storm."
Meteors are created when sand- or pebble-size grains strike Earth's
atmosphere at high speed and create streaks of superheated air along
their paths. The Leonids, which are one of a dozen or so annual meteor
showers caused by streams of cometary debris, arrive at a blistering
44 miles (71 kilometers) per second -- the fastest known. Two years ago
the Leonids briefly peppered the skies over Europe and the Middle East
with 3,000 meteors per hour (nearly one every second). In 1966 lucky
observers in the southwestern United States gaped in awe for 20 minutes
as Leonid meteors fell at the rate of 40 per second!
In the November 2001 issue of SKY & TELESCOPE, meteorologist Joe Rao
assesses the predictions provided by three teams of specialists, who
agree that two dramatic storms appear likely this month.
A burst lasting perhaps two hours is expected in the predawn hours of
November 18th for observers throughout most of North and Central America.
The maximum rates should occur near 5:00 a.m. EST (corresponding to
4:00 a.m. CST, 3:00 a.m. MST, 2:00 a.m. PST). With no moonlight spoiling
the view, the storm may briefly spawn anywhere from several hundred to
1,000 or 2,000 meteors per hour for observers with clear, very dark
skies. A fourth prediction, issued recently by NASA researcher Peter
Jenniskens, argues that the hourly rate could top 4,000.
An even bigger storm is expected 8 hours later for viewers rimming the
far-western Pacific Ocean. Because these locations lie on the other side
of the International Date Line, this peak occurs before dawn on November
19th. Several thousand meteors may streak across the sky for an hour or
so starting about 3:00 or 4:00 a.m. in eastern Australia (depending on
location); 2:00 a.m. in Japan; and 1:00 a.m. in western Australia, the
Philippines, and eastern China.
"If Earth manages to pass through a thick concentration of material,"
Rao notes, "the upper atmosphere can blaze with meteors storming like a
fiery rain from the Sickle of Leo."
THE PUNDITS' PREDICTIONS
Peak Activity in North America (morning of November 18th)
Hourly Rate Midpoint time Midpoint time
(EST) (PST)
Asher & McNaught 800 4:55 a.m. 1:55 a.m.
Brown & Cooke 1300 8:00 a.m. 5:00 a.m.
Lyytinen & Van Flandern 2000 5:28 a.m. 2:28 a.m.
Jenniskens 4200 5:09 a.m. 2:09 a.m.
(These meteors will be dominated by dust particles shed by Comet Tempel-
Tuttle in 1767, though Brown & Cooke believe the dominant source will be
dust shed in 1799.)
Peak Activity in Asia and Australia (morning of November 19th)
Hourly Rate Midpoint time Midpoint time
(Toyko) (Sydney)
Asher & McNaught 2000 2:24 a.m. 4:24 a.m.
8000 3:13 a.m. 5:13 a.m.
Brown & Cooke 800 2:00 a.m. 4:00 a.m.
Lyytinen & Van Flandern 8500 3:15 a.m. 5:15 a.m.
Jenniskens 1800 2:08 a.m. 4:08 a.m.
2700 2:55 a.m. 4:55 a.m.
(These meteors, which may arrive in two distinct bursts, will be dominated
by particles shed by Comet Tempel-Tuttle in 1699 and 1866, respectively)
IMAGE CAPTION:
[http://www.skypub.com/news/images2001/pr_leonids2001_leonidglobes_big.jpg
(276KB)]
Left: This "meteor's-eye view" shows how Earth will be oriented for the
first expected peak of the Leonid shower on November 18, 2001, at about
5 a.m Eastern time. This is when the various experts predict that Earth
will encounter particles released by Comet Tempel-Tuttle in 1766. While
this entire hemisphere will experience the shower, meteors will only be
visible in the nighttime region to the left. Right: About 8 hours later,
a second and perhaps stronger burst of meteors is expected over the
Pacific Ocean, favoring observers in Australia and eastern Asia. Sky &
Telescope diagram.
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