Sino-Dutch Leonid Expedition 1998

1. Latest news and prospects
2. IMC-97 poster-presentation
3. Promotional booklet
4. Articles on the Leonids 1998
5. Leonids in 1994, 1995, 1996, 1997
6. Information at the DMS FTP-site
7. Leonid 98 Outburst Homepage
8. Links to the 1998 Leonids

Casper ter Kuile

This page presents an overview on the
Leonids 1998 expedition of the
Dutch Meteor Society to China

Updated: October 21, 1998

Leonids 1998: Latest news and Prospects

DMS Leonids '98 meeting 980718 Public Observatory "Bussloo"

1. Leonid '98 Airborne Mission

Status of project as of July 27, 1998


We are working towards bringing the Leonid shower return of November 17 1998 to NASA-TV. The hart of the program will be live images of the night sky over Okinawa Japan taken from the Electra aircraft, interupted briefly by images from the activities inside the aircraft. At NASA Ames, experts in the fields of Astrobiology, Planetary Astronomy, and satellite operations will gather in a studio to discuss the images, the return of the shower, impact hazards, and the scope of the NASA Leonid MAC mission.

Preliminary time schedule:

Local time (Okinawa):      11 pm Nov. 17 (radiant rises) until 6 am Nov. 18 (twilight)

Eastern Standard Time:      7 am - 14 pm November 17

Pacific Standard Time:      9 am - 17 pm November 17

The sky images will show a 30 degree field of view directly above the Electra aircraft. The images will be provided by a Hi-Vision monochromatic HD-TV camera of the Japanese Broadcasting Company (NHK). The signal is transfered from aircraft to a ground-station in Okinawa in NTSC format by a microwave link provided by Wescam Troll of Los Angeles. NHK will collect the signal and provide the transfer to NHK Tokyo over satellite and from there over a satellite link to NASA/Ames Research Center.


The life feed can provide USAF and NASA satellite operators with the possibility to assess the Leonid flux and impact hazard in real-time at the time of the expected return. The HD-TV cameras are sensitive enough to be able to gauge the Leonid activity on a minute-by-minute basis. If no increased enhancement of rates occurs, there will be only about 2 meteors/minute. If the Leonid storm happens, that rate could go up to 2000 per minute (30 per second). The downlink will degrade the sensitivity somewhat, loosing the faintest of meteors, but rates should be high enough for flux assesment.
Hartwig Luthen and Sirko Molau of the International Meteor Organisation have conducted a study (WGN, Journal of IMO 26, 109-117) showing that a visual observer can reliably estimate the flux by watching a TV screen. They asked observers to watch a TV screen showing a realistic simulation of a meteor storm. Observers had no difficulty counting flurries of up to 5 meteors per second. At higher rates, the best procedure was found to be counting meteors in periods of 1 second. Accuracies were of order 20-30 percent for rates up to 90 meteors per second. Surprisingly, there was almost no difference between experienced meteor observers and inexperienced observers.


Hans Betlem and Marc de Lignie of the Dutch Meteor Society, participants in Leonid MAC, will provide ground-based support for flux measurements from locations near Beijing (Xilong Station) and near Delingha (Qinghai Radio Observatory) in a collaboration with Purple Mountain Observatory of Nanjing. This will allow us to extend the flux measurements taken from the aircraft by one or two hours, respectively, if the weather conditions provide clear skies at these locations.


The Canadian radar project received its first funding for deployment in Nov. '98. Unfortunately, the radar part of the airborne mission project may not materialise. Operation in Okinawa is complicated by licensing issues that can not be dealt with in time. Moreover, the radar to be deployed is of Australian making and deployment from Australia is suggested. Instead of renting the Raytheon radar used at Edwards AFB in November of 1997, instrument PI Peter Brown has opted to request the purchase of a new Australian radar of SkyMet. The Raytheon radar did not operate in a satisfactory manner. The SkyMet radar has been demonstrated to detect Leonids of up to +7 to +9 magnitude.


Video cameras with long focal length objectives were field tested on July 25th and found capable of imaging stars to +10 magnitude and meteors to +9th magnitude, complying with requirements. The number of such systems on the airborne mission have been increased to offset the potential loss of the radar.

One of the two lidars (and both telescopes) has been installed on the Electra aircraft and the system is ready for flight tests on August 4/5.

- Peter Jenniskens


Peter Jenniskens
The SETI Institute e-mail: NASA Ames Research Center tel: (650) 604-3086 Mail Stop 239-4 fax: (650) 604-1088 Moffett Field, CA 94035-1000

4. The November Leonids: Will They Roar?

The November Leonids: Will They Roar?
Donald K. Yeomans
Jet Propulsion Laboratory/California Institute of Technology
August 7, 1998

Each November when the Earth runs into the dusty debris from periodic comet 55P/Tempel-Tuttle, some Leonid meteor shower activity is noted. These annual displays of meteors, or shooting stars, seem to originate in the constellation Leo so they are termed Leonid meteors. Normally, the observed rate of the Leonid meteors is about 15 per hour under ideal observing conditions. However, every 33 years or so when the parent comet Tempel-Tuttle returns to the Earth's neighborhood, there is a possibility that the Leonid meteors rates can get substantially higher. In some years such as 1799, 1833, and 1966, when the Earth passed particularly close to the tube of debris following in the comet's wake, there were Leonid meteor "storms" noted of up to 150,000 meteors per hour. Periodic comet Tempel-Tuttle passed closest to the sun (reached perihelion) most recently on Feb. 28, 1998 and a month later on March 5, the comet passed through the plane of the Earth's orbit about the sun.

Another way of saying the same thing is to note that the comet passed through the ecliptic plane from north to south or it passed through its descending node. We can expect the maximum Leonid meteor shower activity when the Earth arrives close to this nodal crossing point on November 17, 1998 at 19 hours 43 minutes Universal Time (UT). The peak Leonid meteor shower activity takes place within one hour but some activity can be observed for a few hours on either side of this peak. Unfortunately for observers located in the United States, the Nov. 1998 shower maximum will occur during daylight hours (2:43 pm local time on the east coast and 11:43 am on the west coast). While some enhanced 1998 Leonid activity may be visible just before dawn for U.S. observers, the Leonid shower maximum should be best observed by those located near the regions of Japan and eastern Asia. In November 1999, the Leonid shower will be best observed from the regions near Europe and North Africa.

Table 1. Predicted Leonid Shower Circumstances.
Although slightly enhanced meteor shower activity was evident in 1996 - 97, impressive meteor showers are most likely in 1998 and/or 1999.

Predicted time of   Observed time

Leonid shower peak  of shower peak     ZHR       Good observing

Date (UTC)  HH:MM      (Hours)      meteors/hr   Locations

------------------  --------------  -----------  --------------------

1996-Nov-17 07:20      05 - 10          60       Eastern U.S.

1997-Nov-17 13:34      12 - 14          40       Western U.S., Hawaii

1998-Nov-17 19:43                   200 - 5000?  Japan, Asia

1999-Nov-18 01:48                   200 - 5000?  Europe, North Africa

As noted in Table 1, the predictions for the times of the 1996 and 1997 maximum shower events were rather accurate and there is no obvious reason to doubt that the 1998 and 1999 predictions will be seriously in error. What sort of Leonid meteor rates can we expect in 1998 and 1999? Meteor shower rates are often expressed in terms of the so-called zenith hourly rate (ZHR) or the hourly rate of meteors an observer would witness under ideal conditions with the meteors appearing directly overhead (at the zenith). The geometric circumstances between the comet's orbit and that of the Earth for 1998 and 1999 are most similar to those circumstances during the Leonid showers in 1866-67 and 1931-32. Since the observed Leonid meteor rates in 1866-67 and 1931-32 were approximately 5000 and 200 per hour respectively, we might anticipate a zenith hourly rate in 1998 and 1999 bounded by the rates witnessed in the earlier events - between 200 and 5000 meteors per hour.

Like the weather, it is extremely difficult to predict the hourly rates of meteor showers. Table 1 is meant only as a rough guide. Peter Brown, a respected researcher of the Leonid meteor phenomena, has suggested a more optimistic prediction of between 1000 and 9000 meteors per hour in 1998 (zenith hourly rate). In any case, it is well worth the effort to observe the upcoming Leonid meteors since it will be another century after the 1998-1999 events before significant Leonid meteor displays are once again likely.

Suggestions for further reading:

  1. Meteor Streams (
  2. Kronk, G.W. 1988. Meteor showers, a descriptive catalog. Enslow Publishers, Hillside, N.J.
  3. Mason, J.W. 1995. "The Leonid meteors and comet 55P/Tempel-Tuttle". Journal of the British Astronomical Association 105(5):219-235.
  4. Rao, J. 1995. "The Leonids: king of the meteor showers". Sky and Telescope 90:24-31.
  5. Yeomans, D.K. 1991. Comets: A chronological history of observation, science, myth, and folklore. John Wiley and Sons, N.Y.
  6. Yeomans, D.K., K, K. Yau, and P.R. Weissman 1996. "The impending appearance of comet Tempel-Tuttle and the Leonid meteors". Icarus 124:407-413.

5. Satellites May Be Shattered By Invisible Meteors

THE Leonid meteor storm that may light up the sky in Asia when it strikes the Earth next month could pose a bigger threat to satellites than astronomers had feared.

Every year, around mid-November, the Earth crosses the orbit of a comet called Tempel-Tuttle and passes through debris the comet has shed. This burns up in the upper atmosphere as a meteor shower. Every 32 to 33 years, the Earth runs into an especially dense cloud of debris, turning the shower into a storm. At the peak of the last storm, in 1966, the skies above North America were lit up by 5000 meteors in just 20 minutes.

Astronomers are now bracing themselves for the next Leonid storm, predicted to reach a peak around 17 November. Communications and other satellites could be threatened by the bombardment -- and both NASA and the Russian Space Agency have postponed launches until the danger has passed.

No one knows just how bad the damage will be. For example, astronomers can't predict with certainty exactly where the densest part of the debris cloud is. Now Duncan Steel, an astronomer with Spaceguard Australia in Adelaide, has thrown another variable into the equation. If his model of the chemical composition of the Leonid meteors is correct, attempts to observe the approaching meteors may detect only a few per cent of them.

Steel says that data gathered during the recent visits by comets Hale-Bopp and Hyakutake reveal that the dust these comets gave off was rich in volatile organic compounds. If the same is true of the cometary debris that forms the Leonids, most of the meteors may be invisible. This is because if they are made of highly volatile material, many will burn up at relatively low temperatures -- too low to leave behind glowing trails detectable from the ground. Cool-burning meteors will also emit relatively few electrons, and that will make them invisible to ground-based radars, which can only spot electron-dense trails.

"If small meteoroids in storms are largely composed of organics, then none of the data collected to date gives a realistic assessment of the hazard level," says Steel, whose conclusions are published this week in the journal Astronomy and Geophysics (vol 39, p 24).

Current estimates put the risk of a serious impact between a meteor and a large satellite at about one in a thousand. Steel says his study suggests that this "seriously underestimates" the hazard. "If I am right, the economic loss caused by the Leonids may be immense," he says.

Other astronomers agree that the reliability of the storm predictions depends crucially on the composition of the meteors. "Steel's paper is very interesting -- though whether it is actually correct is another matter," says Iwan Williams of Queen Mary and Westfield College, London. "We may know after the Leonids next month."

Steel's advice is not to rely too heavily on satellite communication and navigation systems in the coming month. "I would not depend for my life on the Global Positioning System being fully functional on 18 November," he says.

Author: Robert Matthews

New Scientist issue 3rd October 1998

9. 14th Air Force experts explain upcoming meteor storm

Air Force News Service

Released: 20 Oct 1998

14th Air Force experts explain upcoming meteor storm
By Capt. Robyn Chumley, 21st Space Wing Public Affairs

VANDENBERG AIR FORCE BASE, Calif. (AFPN) -- When the much-anticipated Leonids meteoroid storm strikes in mid-November, the Air Force will bank on a handful of experts to have prepared for the difficulties the service's space assets could face.

Experts like Capt. Bruce Bookout, who first watched Leonids' bright bolide meteors brighten the nighttime sky while growing up in Florida. A self-admitted astronomy junkie, Bookout jumped at the chance to work the first Leonids meteoroid storm in 32 years.

"My first reaction was, 'Oh, jeez, we've got a thousand questions to answer,'" he said of the initially mind-boggling task. Bookout, assigned to the 21st Space Wing at Peterson Air Force Base, Colo., was the chief of space surveillance analysis for the 21st Operations Support Squadron there. His charter was to examine what would happen to the wing's ground-based missile warning and space surveillance assets during the Leonids storm.

What are the Leonids?

It begins with the comet Temple-Tuttle -- a fairly "young" comet that is a couple hundred thousand years old. Comets -- essentially dirty snowballs -- start spewing off ice and dust as they near the sun's heat, creating streams of house-dust sized meteoroids behind them. The comet Temple-Tuttle is no different, except that its 33-year-long elliptical orbit around the sun -- which takes it almost to Uranus -- leaves clouds of meteoroids right in the Earth's annual orbital path.

This intersection with the comet's meteoroids produces a celestial fireworks display -- an annual meteor shower that appears to the casual observer to emanate from the constellation Leo. It's a fairly routine event, with these dust particles producing a show much like the summertime Perseids. Ordinary, that is, until the Earth's track around the sun crosses comet Temple-Tuttle's tail just months after the comet blew past the sun, something that will happen Nov. 17.

The result: The potential for one son-of-a-gun sandstorm in space for satellites. Thirty-two years ago, the Leonids produced an estimated 150,000 meteoroids per hour. Researchers place this year's storm count at anywhere from a stormy 10,000 per hour, to the relatively tame 200 per hour. In comparison, an average shower -- Earth encounters about 12 of them a year -- tends to be benign, with only 10-15 meteoroids an hour.

But in 1966, there were only 100 active satellites in space; now there are more than 500. With grains of sand averaging the diameter of a human hair traveling at 43 miles per second, an impact on a satellite might put a hole in it -- or, of more significance, create an electrostatic discharge that could potentially cripple a satellite's electronics.

That's where Bookout and others like Capt. Joel McCray come into play. Two years ago, McCray's commander sent him to a University of Western Ontario conference led by noted Leonids expert, Peter Brown. He left the conference cautiously concerned about what the 1998 or 1999 storms could do to the Air Force's space assets.

For 18 months, the chief of the requirements element in the 55th Space Weather Squadron, 50th Space Wing, Schriever AFB, Colo., immersed himself in Leonids. McCray's early pivotal role was gathering experts from each Air Force satellite system together to explore the storms potential.

As early research unfolded, anxiety amplified -- particularly anxiety with the speed of those pencil-tip size particles. Meteoroids normally travel at about 12 miles per second; but because of the relationship of the Earth's orbit to Temple-Tuttle's orbit, Leonids meteoroids rocket past at the speed of a 22-caliber bullet.

The collision causes a "plasma discharge," which is when a particle impact creates an electrostatic discharge that gives a voltage spike on the surface.

If an impact occurs; if the resulting impact causes a discharge; if the discharge gets inside the satellite vs. escaping into the space environment; if the path of that discharge hits an electrical component, then the result could be a fried satellite. But that's a lot of "ifs."

Regardless of the uncertainty, the Air Force's Leonids Tiger Team -- a team of space operations experts -- is considering and preparing for each potential "worst-case" scenario, said Capt. David Hembroff, a space environment operations officer at 14th Air Force, Vandenberg AFB, Calif.

To minimize the storm's damage, the Tiger Team determined a comprehensive series of mitigation strategies to protect space assets and allow the Air Force to continue its vital missions. These strategies include normal precautions such as powering down unnecessary onboard electronics and reducing a satellite's cross-section.

"Plan for the worst, hope for the best," Hembroff said of the Tiger Team's approach.

Bookout likened it to classic military strategy. "We gathered intel on the 'enemy,' and prepared for the 'enemy,'" he said. "We could be preparing for the biggest nothing -- but we will be fully prepared for something and hope for nothing."

Before the storm, satellite anomaly resolution teams [SART] will stand by to quickly resolve any problem that arises. A SART comprises a satellite system's contractors, engineers and operations personnel, and it usually forms to analyze what happened to a satellite after a problem occurs. Maj. John Kress, operations officer with the 821st Space Group at Buckley Air National Guard Base, Colo., expects to be part of a SART during the Nov. 17 storm.

Kress is the Tiger Team's Defense Support Program satellite expert. Though he initially thought Leonids "a big deal," as his analysis increased his pucker-factor with the storm decreased.

"Although there is such a difference in analysis, it all comes down to probabilities," he said.

An unfortunate reality, Lt. Col. Doug Hine said of the probability factor. "That's why we've done such a thorough analysis across-the-board with our satellite systems, because you don't know exactly how things will play out," the chief of current operations for 14th AF said. "We have to be prepared for every contingency."

While most of the key players on the Tiger Team were "subject matter experts" already -- and astronomy hobbyists to boot -- Master Sgt. Terry Rich joined the team with barely a surface understanding of the difference between a meteoroid and a meteorite. A weather forecaster by trade, and 13 years of computer programming under his belt, Rich's role was to develop a 3-D computer modeling product to look at potential places a satellite could be hit. His information helped satellite operators compile a 245-page contingency plan.

Building that contingency plan was a tremendous learning curve for Rich, noncommissioned officer in charge of the weapons and tactics flight for the 50th Operations Squadron at Schriever AFB.

"I knew nothing about Leonids before this," he said. "Now I'm considered one of the 50th Space Wing's experts."

He found it fascinating from day one.

"Consider the speed (of the meteoroids) and the damage it can cause," he said. "A grain of table salt could punch a hole in a satellite. It amazes me that something that small and that light could do that kind of damage."

Bookout considers the Leonids storm "a good thing."

"The more we're out in space, the more we need to learn about this," he said. "It will help us realize how many 'threats' in space will make it tough to do our job. It's a learning process that we need to go through."

It is an important learning process because the Earth will cross comet Temple-Tuttle's path again in 1999 and some predict next year's storm will be worse than this year's.

"People can debate all day long about which year will be worse," Hembroff said. "Let the scientists debate the scientists. We know the what and when about the storm. We have to consider the worst-case scenario -- that we're going to get hit -- then prepare for that, wait and see what happens."

Two years of work for this Tiger Team, and it all boils down to one nail-biting day. The chance that one of the Air Force's satellites will be hit Nov. 17 is relatively small, Hembroff said. "But the fact there is a chance means we have to be prepared."

IMC-97 poster-presentation

Planning a scientific expedition to observe the Leonids of 1998 from a location in East Asia.

Carl Johannink, Marc de Lignie and Casper ter Kuile (Dutch meteor Society)


From early 1997 onward, plans started to be developed within the Dutch Meteor Society to organize an expedition to east Asia in order to observe the Leonid storm of 1998. Active members in the discussion are: Carl Johannink, Marc de Lignie, Marco Langbroek, Peter Bus, Robert Haas, Koen Miskotte, Jos Nijland and Casper ter Kuile. In this poster we will describe our efforts until now and our plans for the near future.


According to Yeomans {ref}, the 1998 storm will most likely occur near 19:45 UT on November 17. With this in mind, Carl Johannink and Casper ter Kuile have investigated possible locations suitable to observe the event. Primary criteria on which locations were judged were connected to a suitable observing window: amongst others the rise of the radiant and the start of twilight. Another important aspect is climatology. After gathering information for several regions and having compared these against each other we concluded that an observing location in central China would best fit our needs, other regions providing problems on the climatic or astronomical side of the issue. The upcoming 1997 apparition could possibly lead to some changes in prefered region if peak times show to be dramatically different, but currently China scores by far best on several selection criteria.

This graph shows the elevation of the Leonid radiant and the sun at various locations in China. The best observing window is between 18:00 UT and 21:30 UT.


This expedition will be a 'serious' expedition, aimed at gathering data of scientific value using visual, multistation photographic and video-observations and radio observations. Determining high accuracy photographic orbits of meteoroids and establishing influx-data with video- and visual techniques will be primary goals. Other observations considered are a.o. spectral photography. It is critical that photographic and video-observations be carried out from three locations about 50-100 kilometers apart. Visual and radio-observations could be done from one location, yet it is always better to spread the risk of bad weather and thus set up at least two stations. For the same reason it is best to set up three instead of two stations for accurate multistation photographic and videowork.


A very important aspect in the setup of this expedition is the local organisational structure required. One cannot setup an expedition as intended without a Chinese counterpart and logistic support provided by a local organisation. As explained above we intend to mount a network of three separate stations to perform multistation photographic and video orbital determinations. This invokes problems with transport, permits, manning and equiping all stations etcetera. This is why we think international cooperation will be needed and could be the only sure guide to succes.


Besides mounting this 'on land' expedition to Asia, DMS is involved in the plans for a coordinated airborne mission lead by Dr. Peter Jenniskens of NASA/Ames. DMS is an official co-investigator in this project.
More information regarding the airborne mission of Peter Jenniskens can be found at:


D.K. Yeomans, K.K. Yau, P.R. Weissman: The impending appearance of comet Temple-Tuttle and the Leonid meteors. Icarus 124 (1996), 407-413.


8. MAP

This map shows the region where the Leonids 1998 are best observed. From Mongolia in the North to Thailand in the south and from Tibet in the west to Korea in the east.
The Gobi desert provides the best climatological conditions but will be difficult to travel while the coastal areas of China are well reached by plane but clouds are more likely to interfere observations. Members of the Dutch Meteor Society are investigating locations in this region to find out which one will best fit their requirements.

Sino-Dutch Leonid Expedition 1998
Investigating a Unique Meteor Storm in China

This information booklet is published by the Dutch Meteor Society (DMS)

and is available in Adobe Acrobat
PDF-format too from our
DMS FTP-site. (608 kB)

Groupphoto of team-members of the
Sino-Dutch Leonid Expedition 1998

1. Introduction

In November of 1998, astronomers are awaiting a unique opportunity to observe a very rare celestial phenomenon. 33 Years after that last happened, comet P/Tempel-Tuttle has returned into the inner parts of our solar system, thereby passing close to the orbit of the Earth. From such previous returns, e.g. that of 1965/66, it is known that the Earth will traverse through the dense trail of dust released by the comet into space. During this traverse, which takes a few hours, the dust particles will enter our atmosphere and will become incandescent; the friction developed when the dust particles pass trhrough the dense atmosphere with the astronomic speed of 71 km/sec causes the particles to burn and illuminate. The high numbers of dust particles entering our atmosphere will result in the appearance of tenthousands of shooting stars (meteors) in the sky; this is the rare and unique phenomenon of a 'meteor storm', one of the most astonishing events that can take place in the night sky. This century, such intense 'meteor storms' (not to be confused with the much more modest, and much more common 'meteor showers') have only been observed in 1933, 1946, and 1966 so far.

2. The 1998 Leonid Meteor Expedition to China

The Dutch Meteor Society (DMS), in cooperation with the Chinese Purple Mountain Observatory (PMO) of Nanjing, is organizing a scientific observational expedition in order to study this rare astronomic event. Some 17 members of DMS will travel to China, the part of the World which will have the best view on the event. They will bring with them special photographic- and video- equipment, in order to record the expected meteor storm with scientific precision. Including test-runs of the equipment and the travel to remote observing locations, the whole expedition will take some two weeks, with the expected meteor storm (which is called the 'Leonids', after the constellation from which they appear in the sky) during the night of November 17-18 as the ultimate goal. In order to eliminate the risk of failure due to bad weather to the highest possible degree, separate observational networks will be established by two geographically well-separated teams. One team will take position in the vicinity of Beijing at the Astronomical Observatory of Xinglong, the other team will travel to remote Delingha in the Qinghai Province of central China. Both locations have the advantage of favourable climatologic conditions in this time of the year, and by their geographic locations offer the best possibilities to observe the meteor storm. During several nights around the date of the expected meteor storm, the observers will challenge the nighttime cold -night-time temperatures go down to -15m C at 3000m altitude in Delingha- in order to sample the meteor activity. Special clothing and equipment are necessary to keep technical equipment and observers alike running under these conditions. Needless to say, the expedition will take all efforts to ensure succesfull observations on the meteor storm. And such a joint success of international importance will be a good base to further cooperation between Dutch and Chinese scientists.

3. Scientific importance

The observations conducted by the expedition are designed to result in a better understanding of how dust particles are ejected from their parent comet, how they behave as part of the interplanetary matter, what their size distributions and orbits through the solar system are. Answers to these kind of research questions, of which still little is known, can add considerably to the results obtained by spacecraft missions such as the Giotto mission to comet Halley in 1986. In addition, more kowledge is gained about objects and events that can be a threath to Earth and artificial satellites. For this purpose, the observational results obtained have to be of high accuracy. Exact timings of their appearance and high precision photographic observations will enable computation of highly accurate orbits of the meteors, video-observations and counts will provide accurate data on their rate of appearance and size distribution. Employed for this purpose is photographic and video equipment specially developed for this task: arrays of computer-controlled photographic cameras including devices to measure speeds; video cameras equiped with image-intensifying technology that are able to film low light level phenomenon; and equipment that makes use of scattered radio waves to detect meteor activity.

4. Cooperation with Chinese investigators

China has a long standing and rich astronomical tradition that started centuries ago. Ancient records written in Chinese, some dating back to several centuries before the birth of Christ, provide some of this worlds earliest historic sources about celestial phenomenon. In more modern times, Chinese astronomy suffered from limited resources, the cultural revolution and limited communications with the international community. That is now changing, and the predicted occurence of the unique Leonid meteor storm over China in November of 1998 might provide a boost to further international cooperation.
The Chinese Academy of Sciences wants to take this opportunity to intensify its contacts with foreign scientists. They choose to enter a joint programm with the Dutch Meteor Society (DMS), who has an established expertise in this type of observations. The Dutch Meteor Society hopes to be able to encourage Chinese efforts in meteor astronomy by offering to share some of its expertise during the Leonid meteor storm of 1998. Over the past 15 years, the Dutch Meteor Society has succesfully organized a number of observational expeditions of this type that have yielded significant results. Currently, DMS is the worlds primary contributor of high accuracy observational data on meteors (Acrobat-PDF via ftp-download: 260kB).

5. Media attention

An impressive celestial event like the Leonid meteor storm of 1998 is expected to attract some media attention: when the whole sky is being filled with meteors, it looks like the Earth is moving through the stars at high speed. This offers some prospects for media attention for our expedition too. The event and the expedition are expected to have news-value most notably around November 1998 and possibly also November 1999, when we expect a smaller 're-run' of the event to take place over Europe. In recent history much more modest events of this kind and some of our earlier expeditions have been target of media attention. For the upcoming event and expedition, we plan to intensify our media contacts by offering press releases and pictures. One topic that is expected to arrouse some interest is the possible threath of this event to artificial satellites, e.g. communications satellites. These must do without the protective cover supplied by our atmosphere to the inhabitants of the Earth, and can be damaged when hit by one of the dust particles in the meteor storm. During a much smaller meteor display in 1993, a launch of the Space-Shuttle was postponed for that reason.

6. Sponsoring opportunities

It is clear that a project as described above demands a lot of organizational efforts and financial support. All DMS members are non-paid volunteers who do this work besides their regular work and the DMS activities are usually employed without permanent financial support. Members of the Dutch Meteor Society have invested considerably into their equipment over the last few years, and for this expedition both this equipment and a considerable number of people have to be moved over a large distance. The China Committee of the Royal Dutch Academy of Sciences (KNAW) is supporting the current 1998 Leonid Expedition. Funding proposals have been submitted to a number of other non-commercial funds who have supported special DMS activities in the past.
The Dutch Meteor Society is actively solliciting support and sponsorship for the 1998 Leonid meteor storm Expedition to China. Most notably, we are solliciting support from Dutch and international companies that are active on the Chinese market and are positive towards the idea of promoting scientific cooperation between China and other countries. Sponsorship and other gifts are under the care of the Foundation Euregio Public Center for Astronomy and are therefore tax-deducable. The Foundation has ample experience with sponsor-ships, and will guarantee a good representation of sponsors in the project. In close cooperation with the commercial sponsors, DMS will try to convert media attention for the project into high visibility of the project and its sponsors. This includes posibilities for depiction of company emblems on photo- and video-materials, and mentioning sponsorships in newspapers, astronomical magazines, scientific articles and if possible radio- and tv-items. Supplying photographic and video materials of the expedition for promotion activities is also one of the possibilities.

7. Information contact

For more information with regard to possible sponsorships and donations, please contact:

Dutch Meteor Society,
"project Sino-Dutch Leonid Expedition 1998"

  1. Hans Betlem, Lederkarper 4, NL-2318 NB Leiden, The Netherlands, Phone: +31-71-5223187
  2. Carl Johannink, Schiefestrasse 36, D-48599 Gronau, Germany, Phone: +49-2562-22345
  3. Ben Kokkeler, Otto Klempererstraat 111, NL-7558 EN Hengelo, The Netherlands, Phone: +31-74-2772199
  4. Casper ter Kuile, Akker 145, NL-3732 XD De Bilt, The Netherlands, Phone: +31-30-2203170
  5. Marc de Lignie, Prins Hendrikplein 42, NL-2264 SN Leidschendam, The Netherlands, Phone: +31-70-3205673

Intermezzo 1: The Dutch Meteor Society (DMS)

The Dutch Meteor Society, founded in 1979 by Hans Betlem, is a Society that promotes the observation of meteors ('shooting stars'). About twenty active members regularly conduct visual, photographic, video and radio-MS observations on meteors. These observations are analysed and reported on in the Societies' own bimonthly Journal 'Radiant'. In close cooperation with a number of respected foreign scientists, further analysis and reports are being published in international Scientific Journals like the Astrophysical Journal, Astronomy & Astrophysics, Meteoritics & Planetary Science etc.

DMS has organized a number of observational expeditions, including campaigns to observe the annual Geminid meteor stream in 1990 and the Perseid meteor outburst of 1993 from Southern France; The Leonids and the unique and important alfa Monocerotid outburst from Southeast Spain in the highly successfull expedition of 1995; and the Leonids of 1997 from the USA. The Society has its own website with timely news and results:

Intermezzo 2: What are 'meteors'?

Meteors (or: 'shooting stars') are small dust particles with an origin in space. They are released from the nuclei of comets (e.g. like recent comet Hale-Bopp), that loose the dust when evapora-ting the outer layers of their nuclei while passing close to the Sun. Some comets move in orbits that cross very close to the orbit of the Earth: the result is that the Earth traverses through the trail of dust left by the comet in its wake. The dust particles enter the atmosphere surrounding our planet: the high speeds and air density causes friction and heat release, which makes the dust particle burn and the air around it incandescent. For a fraction of a second, this results in a streak of light shooting accross the sky: 'shooting stars'. The dust trails that cause the meteor activity are encountered each year around the same date. For example, conspicuous numbers of meteors are visible each year around January 4, August 13, November 17 and December 13. This are the so called 'annual meteor streams' or 'annual meteor showers'. The streams are called after the point in the sky from which they (due to perspective) seem to emerge: e.g. the November 17 meteors seem to emerge from the constellation Lion (Leo in Latin) and hence are called the 'Leonids'. When looking into the direction of the Lion, we are looking into the direction of the orbit of comet Tempel-Tuttle from which the dust particles originate.

Intermezzo 3: Comets, Meteor Storms, and the Leonids

Comets move in very wide orbits. Most of their time, they are at far distance from both the Sun and Earth. But when they do come close to Earth occasionally, the Earth can encounter the very dense dust cloud immediately surrounding the comet. This is the rare occasion when there is prospect for a true 'storm' or 'rain' of meteors. On an average night only 10 meteors per hour appear: during an annual meteor stream disply this can go up to several tens per hour. But on the occasion of a true 'meteor storm', thousands of meteors can appear in one hour time! The sky then becomes filled with meteors (often several per second!), a phenomenon which, according to the descriptions, must be an astonishing sight. Ancient Chinese wrote: 'At midnight, stars fell like rain'. These kind of phenomena last only short: 2-3 hours at best.

Scott Murrell at New Mexico State
University Observatory

This century, such intense 'meteor storms' have only been observed with certainty in October of 1933 and 1946 (the Draconid stream) and November of 1966 (the Leonids), and none of these events has been recorded and studied with modern observing equipment so far. Comet P/Tempel-Tuttle (discovered in 1865/66) has an orbit that brings it close to Earth each 32-33 years. It was dust released by this comet that was responsible for the impressive meteor storm that was observed from the USA on November 17 1966. In the early spring of 1998, 33 years after its last apparition, the comet passed close to Earth again. This year and next year on November 17-18, the Earth will traverse through the dense dust clouds in the wake of the comet. From former apparitions (e.g. 1966, 1866 and 1833) it is known that the dusttrail near the comet is that dense that an astonishing meteor storm can appear with on past occasions more than 10 000 meteors having been counted in one hour. It takes the Earth only 2 hours to traverse through this dense dust trail, but the trail is long enough to produce spectacular meteor activity up to two years after the passage of the comet. That makes very good prospects for a meteor storm in 1998 and possibly also 1999. When and where we will see the storm is determined by the actual moment that the Earth meets the trail. In 1998 that will be favourable for central Asia (China), in 1999 for east Europe.

Articles on the Leonids 1998

Prospects on the Leonids 1998

E.P.Bus, Eerste Spoorstraat 16, NL-9718 PB Groningen

It appears there is a relation between the distance in the orbits of the Earth and comet 55P/Tempel-Tuttle and the time of outbursts after the comet's perihelion passage when the Earth has crossed the comet's orbital plane.
An extrapolation departing from the 1833, 1866 and 1966 peak positions, the time of the outburst in 1998 was calculated for November 17 at about 21h38m UT.
However, because the latest orbital elements of comet 55P/Tempel-Tuttle (Epoch July 6.0 TT, 1998 and for Epoch Jan. 22.0 TT, 1999) it appears that the calculated time of maximum is now about 25-minutes later at about 22h03m UT (± 36m), around solar longitude lo 235°.373 (± 0°.024).
In principle the window of opportunity stretches from about 21h25m until 22h40m UT.
A first peak close before the comet's node at 19h43m UT is still very likely.
However, because the extrapolations there is considerable room for deviations from the values given as a 'best estimate' above.

Figure 1. The activity of the Leonids as given in de literature [7,8,9] around two days before and after the Earth crosses the comet's orbitplane. Most of the given times are, according to the authors, estimations and is probably the course of the high scatter and the very low correlation. "Storms" are marked by diamonds and "showers" or "high activity" by triangles. The dot represents the expected position of 1998. The trend of higher activity after the comet's node than before is clearly noticeable in the figure. The data of 1097, 1399 and 1800 are missing because the day of maximum is very uncertain and the date of 1582 is missing because the given day is 11,5 days after the node. This day is probably wrong because of the Gregorian calendar reform in that year, 4 October 1582 is followed by 15 October 1582.

Figure 2. This diagram is equal to figure 1 except only data after the comet's perihelion passage is taken into account.

Figure 3. Correlation between the comet and the Earth orbital distance and the time of maximum activity of the Leonids after the comet's node within a year after perihelion passage of the comet. The red line represents the mean result between the different analyses: Squares represent the analysis of Kresák and open circles represent the analysis of Jenniskens and triangles the analysis in this paper.

Figure 4. Relation between the number of Leonids per second at peak activity and the orbital distance between the Earth and the comet. The line represents the results of the model (open circles). The squares represent the analysis of Kresák, dots represent the analysis of Jenniskens, diamonds represent the analysis of Langbroek and triangles represent the analysis in this paper.


  1. Jenniskens, P., Meteoritics & Planetary Science, 31, 177-184 (1996)
  2. Jenniskens, P., in "1996-98 Leonid Outburst Event Summary",, (1998)
  3. Yeomans, D.K., K.K.Yau and P.R.Weisman, Icarus 124, 407-413 (1996)
  4. Langbroek, M., "Leonid outburst activity 1996", poster IMC (1998)
  5. Hasegawa, I., in "Meteoroids and their parent bodies", J. Stohl and I.P.Williams (eds.), 177-180, (1993)
  6. Curry, P.A., Mon. Not. R. Astron. 93, 3, 190-192 (1933)
  7. Yeomans, D.K., Icarus, 47, 492-499, (1981)
  8. Kresák, L., Astron.Astrophys. 279, 646-660 (1993)
  9. Mason, J.W., J. Br. Astron. Assoc. 105, 5 (1995)
  10. Jenniskens, P., Astron. Astrophys, 295, 206-235 (1995)
  11. Milon, D., J. Br. Astron. Assoc. 77, 2 (1967)
  12. Maanders, E.J., Hemel en Dampkring, 65, 6, 149-160 (1967)
  13. Heath, T., Atlas of Popular Astronomy, Plate X, (1922).
  14. Marco Langbroek, Privé communicatie, (juni 1998)

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