The Leonids are coming, The Leonids are coming!

The Leonids are the debris of Comet 55P/Tempel-Tuttle. Every 33 years or so, the comet returns to the inner solar system and releases material that forms into a new dust trail. In 2001 November the Earth will pass near the trails released at the 1866, 1767 and 1699 returns, i.e. 4 revolutions, 7 revolutions and 9 revolutions of the comet ago. The Earth's passage right through the centre of trails is associated with the most spectacular meteor displays (studies show that, as well as how close to the centre of the trail you are, the strength of the display also depends on how far along a trail's length you are). Here are world maps with storm predictions:



Northern California Leonid Observing Programs

(check frequently for updates)

OAKLAND -- Join astronomers at Chabot Space & Science Center for a special meteor shower observing session. Telescopes will be set up and astronomers will interpret the eveninnng's events. Time is from 10:00 p.m. on Saturday, November 17 until dawn on Sunday, November 18. Chabot telescopes will be open for viewing before 10:00 p.m.as they are every clear Friday and Saturday night. Tickets $5 (includes hot beverage and snack) Buy tickets online http://www.ticketweb.com/user/?region=sfbay&query=detail&event=282092 or call the box office at (510) 336-7373. Maps and more here http://www.cosc.org/visit/observatories.asp

BERKELEY -- Lawrence Hall of Science holds Saturday Night Stargazing first and third Saturday nights on the plaza. Join astronomers on November 17th Telephone: (510) 642-5132 and select #7, maps and more here http://www.lhs.berkeley.edu/planetarium/SatNightStars.html

SONOMA -- The Robert Ferguson Observatory at Sugarloaf Ridge State Park in Sonoma County has public observing on November 17 through RFO telescopes. Viewing through telescopes 9:00 p.m. to midnight, and at noon that day for solar viewing. Telephone: (707) 833-6979. Maps and more here http://www.rfo.org.

FREMONT PEAK -- The Fremont Peak Observatory in Fremont Peak State Park near San Juan Bautista will offer Leonid Meteor Storm observing (and researchers will be there to visially and photographically count and image the meteors) on November 17th. Telephone: (831) 623-2465. Maps and more here http://www.fpoa.net

SAN MATEO -- The San Mateo County Astronomical Society plans a starshow at the College of San Mateo on November 17th, Leonid Storm night. Activities include include displays, exhibits, slide show, featured speaker, continuous videos, free handouts, kids activities, computer with astronomy software, Internet connection, planetarium shows, and, of course, stargazing with telescopes. It will, of course, be free, and open to the public. Telephone: 650/579-3586. Directions and more here: http://www.homestead.com/SMCAS/index.html

SAN JOSE -- Join astronomers from the San Jose Astronomical Assocation at Henry Coe State Park near Morgan Hill for Star gazing and Leonids in November 17/18. Henry Coe State Park is located east of Morgan Hill in the Hamilton Range. Telephone: (408 559-1221) Map and more: http://www.sjaa.net/coe.html

SAN FRANCISCO/MT. TAMALPAIS -- Join the San Francisco Amateur Astronomers at the Rock Springs Parking Lot at Mount Tamalpais State Park for the Leonids on November 17/18. Mount Tamalpais is located in Central Marin County. Telephone hotline (415) 566-2357 Map and more: http://www.sfaa-astronomy.org/sfaa/starparties/tammap.shtml

Radio Meteor tutorial:


Want to Photograph meteors?


History of the Leonids


Background facts about the Leonids:


Storm Fever: Where are the meteor observers going around the world:


Estimate the 2001 shower rates from your location:


Encounter rates for November 18, 2001


The All-Purpose Meteor Observing Guide:


--Jane Houston Jones

San Rafael, CA



Date: Mon, 29 Oct 2001


San Francisco, Calif. -- 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.nasa.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."

The November/December 2001 issue of Mercury contains a feature article by Dr. Jenniskens chock full of fascinating information about meteor science. Jane Houston Jones contributed an informative sidebar about how best to observe the Leonids. You can read these articles by visiting http://www.astrosociety.org/pubs/mercury/1101pr/leonids.html.

The non-profit Astronomical Society of the Pacific was founded in 1889 in San Francisco, and is still headquartered there today. The ASP has since grown into an international society. Its membership is spread over all 50 states and 70 countries and includes professional and amateur astronomers, science educators of all levels, and people in the general public. The ASP publishes the bimonthly Mercury magazine (now published in full color) for its members. It publishes a technical journal for professional astronomers, and it coordinates Project ASTRO, a national astronomy education program. The Society also produces a catalog of extensive astronomy-related products for educators and the public.

Astronomical Society of the Pacific 390 Ashton Avenue San Francisco, CA 94112 http://www.astrosociety.org (415) 337-1100

Contact: Robert Naeye, Publisher/Editor, Mercury magazine (415) 869-2913 rnaeye@astrosociety.org

Page web-posted by Alan Gould--Lawrence Hall of Science