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(meteorobs) Excerpts from "CCNet 109/2000 - 27 October 2000"
------- Forwarded Message
From: Peiser Benny <B.J.Peiser@livjm.acdot uk>
To: cambridge-conference <cambridge-conference@livjm.acdot uk>
Subject: CCNet, 27 October 2000
Date: Fri, 27 Oct 2000 13:17:47 +0100
CCNet 109/2000 - 27 October 2000
--------------------------------
(1) NEW IMAGES OF DOUBLE ASTEROID & A NEW ASTEROID MOON
Andrew Yee <ayee@nova.astro.utorontodot ca>
(2) POST-MORTEM OF COMET LINEAR
Ron Baalke <baalke@jpl.nasadot gov>
(3) ASTRONOMER SEES RED
Andrew Yee <ayee@nova.astro.utorontodot ca>
[...]
(5) HOW LIFE CAN JUMP BETWEEN PLANETS
Andrew Yee <ayee@nova.astro.utorontodot ca>
(6) MICRO-ORGANISMS FROM THE MOON?
Brig Klyce <bklyce@panspermia.org>
(7) LEONIDS ON THE MOON
Rob McNaught <rmn@aaocbn.aaodot gov.au>
[...]
(9) NEW DEVELOPMENTS IN KANSAS FIREBALL STORY
Mark Kidger <mrk@ll.iac.es>
=============
(1) NEW IMAGES OF DOUBLE ASTEROID & A NEW ASTEROID MOON
>From Andrew Yee <ayee@nova.astro.utorontodot ca>
Southwest Research Institute
Technical Contact:
Dr. William J. Merline, (303) 546-0487, merline@boulder.swridot edu
Media Contact:
Maria Martinez, (210) 522-3305, mmartinez@swri.org
Embargoed for release until Thursday, October 26, 2000, at 3:00 PM EDT
ASTRONOMERS IMAGE DOUBLE ASTEROID AND A NEW ASTEROID MOON
Boulder, Colorado -- Large telescopes with deformable optics are allowing
astronomers to study distant asteroids with unprecedented clarity -- leading
to the discovery of new shapes and configurations and presenting scientists
with new puzzles to solve.
An international team of astronomers led by Dr. William Merline of the
Boulder office of Southwest Research Institute (SwRI) released today the
first-ever images of a large, double asteroid. Each asteroid in the pair is
the size of a large city (about 50 miles across), separated by about 100
miles, mutually orbiting the vacant point of interplanetary
space that lies midway between them. The discovery was made using the W.M.
Keck Observatory atop Mauna Kea, the tallest mountain in Hawaii. The
asteroid pair was once assumed to be a single body, called Antiope, orbiting
the sun in the outer parts of the asteroid belt between
the orbits of Mars and Jupiter.
The team also released a picture of a small moon orbiting the large asteroid
Pulcova. This moon was discovered in February 2000 using the
Canada-France-Hawaii Telescope (CFHT), also on Mauna Kea. It is only the
third asteroid discovered to have a small moon. Asteroid-moon pairs
had not been seen until 1993, when the Galileo spacecraft imaged the
one-mile-wide moonlet Dactyl, as it rushed past the 19-mile-diameter
asteroid Ida. The Merline team reported the second asteroidal moonlet a year
ago, circling the 135-mile-sized asteroid Eugenia. The team named
the companion Petit-Prince, officially accepted by the International
Astronomical Union in August.
"It's getting to be kind of bewildering," says Dr. Christophe Dumas of the
Jet Propulsion Laboratory (JPL), a team astronomer. "Asteroids were once
thought to be single, mountain-like chunks of material, perhaps smashed into
'flying rubble piles' by occasional collisions among
themselves."
Astronomers expect strange new configurations to provide still more
surprises as the survey continues. "Every new asteroidal companion we
discover seems to bring new configurations and new mysteries," says team
member Dr. Clark R. Chapman, also of the SwRI Boulder office.
The team's approach uses a new technology, called adaptive optics, which
enables telescopes to see asteroids and other small points of light in the
heavens with the same clarity as the Hubble Space Telescope. Until recently,
ground-based telescopes were hindered by distortions caused by Earth's
atmosphere, in much the same way water distorts the view of an underwater
object. The new technique passes light from the telescope through a
specialized "correction box" to instantaneously analyze the distorted light
and compute the amount of correction necessary to remove the blurring of the
atmosphere. The correction information is then fed to deformable mirrors in
the box that remove the distortion, providing a sharper image.
A fascinating demonstration of the new telescope technology is in a movie of
the asteroid Kleopatra, also released today, observed during a seven-hour
period. Earlier this year, Steve Ostro of JPL published reconstructions of
Kleopatra's shape based on radar reflections obtained when that asteroid was
fairly close to the Earth in November 1999. During the same month, team
member Dr. Francois Menard, currently a visiting scientist at CFHT, obtained
adaptive optics images. "Excellent agreement of both optical and radar
pictures of Kleopatra's 'dog-bone' shape provides added confidence in the
reliability of adaptive optics images," says Menard.
"Radar works well for asteroids near the Earth, but adaptive optics is much
more powerful for studying asteroids in the middle of the asteroid belt and
beyond," says Dr. Laird Close of the European Southern Observatory and the
University of Arizona.
This week, Merline and his colleagues reported to an annual meeting of
international scientists specializing in solar system studies on two years
of asteroid surveys conducted at three observatories equipped with the new
adaptive optics systems.
"In fact, large asteroidal satellites and twin companions are rather rare,"
Merline told attendees of the 32nd annual meeting of the American
Astronomical Society's Division for Planetary Sciences, convened this week
in Pasadena, California. "Preliminary study of about 200 asteroids has
turned up only two asteroids with moons (Eugenia and Pulcova) and just one
double (Antiope)," he explains. "It is possible that a few more moonlets
might emerge from more sophisticated analysis of the data we have
collected."
Pulcova is an asteroid about 90 miles in diameter. Its small satellite,
roughly a 10th its size, orbits Pulcova every four days at a distance of
about 500 miles.
Asteroidal companions provide vital information about asteroids that has
been difficult to obtain. Until now, the best measurements of asteroid
masses -- their bulk densities, such as whether they are "light" like ice,
"dense" like metal, or in between like rocks -- came from deflections of
spacecraft flying past an asteroid. Such spacecraft encounters are rare, and
deflections of more distant objects (other asteroids or planets) by an
asteroid's gravity are weak and difficult to measure. But an asteroidal
satellite, or twin, is a body whose trajectory is so mightily deflected by
the asteroid's gravity that it is actually forced to orbit around it. The
revolution time provides a measure of the body's mass, hence density.
Using such techniques, Merline's team find that Eugenia, Pulcova, and
Antiope are all rather light bodies. They are much less dense than familiar
rocks, more like ice, but their surfaces appear very dark, like rock.
Interesting differences in the densities motivate further research on
asteroids with satellites.
NASA and the National Science Foundation are funding this research.
Observations are being conducted at the Keck Observatory and the CFHT
(operated by the National Research Council of Canada, the French Centre
National de la Recherche Scientifique, and the University of Hawaii).
Other team members are Dr. J. Chris Shelton (Mt. Wilson Observatory) and Dr.
David Slater (SwRI, San Antonio).
SwRI is an independent, nonprofit, applied research and development
organization based in San Antonio, Texas, with more than 2,700 employees and
an annual research volume of more than $300 million.
EDITORS: Images accompanying this press release will be available at 11:00
AM EDT at http://www.boulder.swridot edu/merline/press .
============
(2) POST-MORTEM OF COMET LINEAR
>From Ron Baalke <baalke@jpl.nasadot gov>
Office of News and Information
Johns Hopkins University
3003 N. Charles Street, Suite 100
Baltimore, Maryland 21218-3843
Phone: (410) 516-7160 | Fax (410) 516-5251
CONTACT:
Michael Purdy, mcp@jhudot edu, (410) 516-7906
EMBARGOED FOR RELEASE ON THURSDAY, OCT. 26, AT 11 A.M. EDT
Astronomers Conducting Post-Mortem on Comet LINEAR
New analysis of observations of Comet LINEAR, a comet whose breakup in late
July and early August made headlines worldwide, has shown that the comet
might have been starting to come apart as early as the second week of June.
"The first hint of trouble for Comet LINEAR came from ground-based
observations at the Lowell Observatory from June 10 to June 12, when
significant variations in the comet's brightness were first detected," says
Hal Weaver, a research scientist in the physics and astronomy at
The Johns Hopkins University.
These variations were originally attributed to rotation of the comet's
nucleus, a common phenomenon known to change the brightness of comets. But
when Weaver recently looked back at the data he began to suspect the change
had links to the comet's eventual demise.
"Although no fragments were detected near the comet at that time, we now
believe that this was the first indication that the comet was coming apart,"
says Weaver, who is reviewing the results on the recently deceased Comet
LINEAR at the Division of Planetary Sciences
Meeting in Pasadena, Calif., on October 26.
Comet LINEAR had been eagerly anticipated by astronomers, who were
predicting that it might become visible to the naked eye in the night skies
during July. While the comet's brightness never lived up to its advance
billing, LINEAR nevertheless thrilled observers by its erratic
behavior and eventual demise.
Observations early in July had suggested the comet was growing less stable.
On July 7, Weaver and his collaborators used the Hubble Space Telescope to
study the comet and captured pictures of a large chunk of the comet breaking
away and moving down its tail, presumably being
pushed away by jets of gas emanating from its surface. These jets are
produced as sunlight boils ice on the comet directly into water vapor. The
gas jets also eject small particles of dust into the coma, or atmosphere of
the comet. Radiation pressure from the sun then sends
this dust streaming behind the comet to form the comet's tail.
Extreme variations in the comet's brightness were detected by optical and
radio telescopes during July 20-24, and astronomers observing the comet over
the next 12 days complained that it looked like little more than a cloud of
dust. Puzzled by what appeared to be a rapid disintegration of the nucleus,
Weaver and colleagues decided to look more carefully at the comet using the
Hubble Space Telescope. The Hubble images revealed a spectacular field of
about a dozen mini-comets near the edge of the broad tail of dust seen in
the earlier ground-based images. Each of the fragments had its own
comet-like tail.
After a scramble to arrange time for follow-up observations, Weaver and his
team observed the comet again on Aug, 6 using the Very Large Telescope in
Chile. Although its resolution was not quite as good as Hubble's, the VLT's
mirror has 10 times the collecting area, and it was
able to detect about 17 mini-comets.
When they went back to the comet on Aug. 9 with the VLT, they were surprised
to find that the mini-comets had virtually disappeared. Poor atmospheric
conditions made it difficult to determine if a real change had taken place,
or if atmospheric turbulence was hindering their view.
But observations on Aug. 14 under excellent conditions confirmed that the
mini-comets had faded dramatically.
Weaver and his colleagues are continuing to analyze the data they gathered
to see if they can find clues to how LINEAR came apart. A better
understanding of the comet's breakup could lead to a better understanding of
how it came together 4.6 billion years ago in the early days of the solar
system.
"If the comet broke up by shedding small pieces, then it's possible that the
most massive object remaining in the field of mini-comets could be
identified as its original nucleus," Weaver says. "On the other hand, it may
be that the destruction of the comet was so complete that it's pointless to
search for the 'original' object, much like you wouldn't call any particular
piece of a badly shattered glass the 'original glass.'"
Astronomers have seen many other comets fragment, Weaver says, but very few
have done so as dramatically as LINEAR. Current cometary theory suggests a
range of forces that could have torn the comet apart, most of which should
manifest more strongly as the comet gets closer and closer to the sun. These
may include sharp temperature and pressure differences between the sunward
and dark sides of the comet, and sudden vaporization of internal pockets of
ice.
"We still do not understand what caused this comet to come apart, and don't
generally understand what causes fragments to break off comets," says
Weaver. "By continuing to investigate the data from Comet LINEAR, and
folding in everything we know about other comets as well, maybe somewhere
downstream we can explain what happened with a detailed physical model."
The HST and VLT Observing Team
* H. Weaver and P. Feldman (Johns Hopkins University)
* M. A'Hearn (University of Maryland)
* C. Arpigny (Liege University)
* J. Bauer (University of Hawaii)
* M. Combi (University of Michigan)
* J. Davies (Joint Astronomy Centre)
* C. Delahodde (European Southern Observatory)
* M. Festou (Observatoire Midi-Pyrenees)
* O. Hainaut (European Southern Observatory)
* R. Hook (European Southern Observatory)
* L. Jorda (Max Planck Institute)
* M. Keesey (Jet Propulsion Laboratory)
* P. Lamy (Laboratoire d'Astronomie Spatiale)
* C. Lisse (Space Telescope Science Institute)
* B. Marsden (Smithsonian Astrophysical Observatory)
* K. Meech (University of Hawaii)
* Z. Sekanina (Jet Propulsion Laboratory)
* I. Toth (Konkoly Observatory)
* G.-P. Tozzi (Arcetri Observatory)
* R. West (European Southern Observatory)
Related Web Sites
* Hal Weaver's Homepage
http://www.pha.jhudot edu/~weaver/
============
(3) ASTRONOMER SEES RED
>From Andrew Yee <ayee@nova.astro.utorontodot ca>
Northern Arizona University
Flagstaff, Arizona
October 25, 2000
NAU astronomer sees red
A mystery among giant comets in the outer solar system
Astronomers from Northern Arizona University and the University of Oklahoma
have made a startling find on the ragged edge of the solar system that may
provide an important clue to the origin and evolution of the solar system.
This discovery is published in the Oct. 26 issue of "Nature."
Stephen Tegler, associate professor of physics and astronomy at NAU, and
William Romanishin, associate professor of physics and astronomy at
Oklahoma, have been using the largest telescope in the world, the Keck 10-m
telescope in Hawaii to measure the surface colors of Kuiper belt objects, an
ancient reservoir of giant comet-like objects at and beyond the orbits of
the most distant planets, Neptune and Pluto.
Tegler and Romanishin find the surface colors of the icy objects to come in
only two colors, red and gray, and the objects that stay the farthest from
the Sun come only in red.
"Our findings are controversial because they are so unexpected,"Tegler said.
"Most astronomers expected the colors of Kuiper belt objects to be the
same."
Kuiper belt objects are thought to have all formed at about the same
extremely large distance from the Sun, about four billion miles away, and
therefore should be made of the same stuff and have the same colors, Tegler
said.
Much closer to the Sun, the asteroid belt marks the boundary between rocky,
inner planets like Earth, and gaseous, outer planets, like Jupiter.
A change in the surface colors between the rocky asteroids in the inner and
outer belt is easier to explain.
Why red and gray surface colors?
In the darkness of the Kuiper belt where temperatures reach a chilly minus
380 F, the surfaces of some objects are rich in a material that strongly
absorbs blue sunlight.
Upon reflection, the lack of blue sunlight gives the objects very red
colors. The gray objects contain little or none of the material that
strongly absorbs blue sunlight. Upon reflection, the material on the surface
of these objects does not change the colors in sunlight, and
astronomers refer to the material as gray in color.
Two different surface types is a puzzle.
Romanishin said, "The existence of two surface colors suggests to us that
something important and unexpected happened long ago in the outer solar
system."
The objects are named after the Dutch-expatriate and Arizona astronomer,
Gerald P. Kuiper. In 1950, Kuiper theorized that the Solar System extended
beyond Pluto. In 1992, David Jewitt and Lane Luu, astronomers at the
University of Hawaii, discovered the first Kuiper belt object. Today there
are nearly 400 known Kuiper belt objects that range in size from small
cities to the planet Pluto which is smaller than the Moon.
Tegler said, "We found patterns that we did not know existed four or five
years ago. Once we understand the patterns, they will give us additional
insight into history of the solar system. What we have now is the ability to
ask more questions."
[NOTE: Images supporting this release are available at
http://www.naudot edu/paffairs/tegler_mystery.html]
=============
(5) HOW LIFE CAN JUMP BETWEEN PLANETS
>From Andrew Yee <ayee@nova.astro.utorontodot ca>
Media Relations
Caltech
Contact: Robert Tindol (626) 395-3631
10/26/2000
New results on Martian meteorite support hypothesis that life can jump
between planets
According to one version of the "panspermia" theory, life on Earth could
originally have arrived here by way of meteorites from Mars, where
conditions early in the history of the solar system are thought to have been
more favorable for the creation of life from nonliving ingredients.
The only problem has been how a meteorite could get blasted off of Mars
without frying any microbial life hitching a ride.
But new research on the celebrated Martian meteorite ALH84001 shows that the
rock never got hotter than 105 degrees Fahrenheit during its journey from
the Red Planet to Earth, even during the impact that ejected it from Mars,
or while plunging through Earth's atmosphere before landing on Antarctic ice
thousands of years ago.
In the October 27 issue of the journal Science, Caltech graduate student
Benjamin Weiss, undergraduate student Francis Macdonald, geobiology
professor Joseph Kirschvink, and their collaborators at Vanderbilt and
McGill universities explain results they obtained when testing several thin
slices of the meteorite with a new state-of-the-art device known as an
Ultra-High Resolution Scanning Superconducting Quantum Interference Device
Microscope (UHRSSM). The machine, developed by Franz Baudenbacher and other
researchers at Vanderbilt, is designed to detect microscopic differences in
the orientation of magnetic lines in rock samples, with a sensitivity up to
10,000 times greater than existing machines.
"What's exciting about this study is that it shows the Martian meteorite
made it from the surface of Mars to the surface of Earth without ever
getting hot enough to destroy bacteria, or even plant seeds or fungi," says
Weiss, the lead author of the Science paper. "Other studies have suggested
that rocks can make it from Mars to Earth in a year, and that some living
organisms can live in space for several years. So the transfer of life is
quite feasible."
The meteorite ALH84001 has been the focus of numerous scientific studies in
the last few years because some scientists think there is tantalizing
evidence of fossilized life within the rock. The issue has never been
conclusively resolved, but Weiss says the matter is not important to the
present result.
"In fact, we don't think that this particular meteorite brought life here,"
says Weiss. "But computer simulations of ejected Martian meteorites
demonstrate that about one billion tons of rocks have been brought to Earth
from Mars since the two planets formed." Many of these rocks make the
transit in less than one year, although ALH84001 took about 15 million
years.
"The fact that at least one out of the 16 known Martian rocks made it here
without heating tells us that this must be a fairly common process," says
Kirschvink.
The sample the Kirschvink team worked with is about 1 mm thick and 2 cm in
length and somewhat resembles the African continent, with one side
containing a portion of the original surface of the meteorite. Using the
UHRSSM, the team found that the sample has a highly aligned and intense
magnetic field near the surface, which is to be expected because the surface
reached a high temperature when it entered Earth's atmosphere.
The reason this is important is that any weakly magnetized rock will
reorient its magnetization to be aligned with the local field direction
after it has been heated to high temperatures and cooled. This critical
temperature for any magnetic material is known as the blocking temperature.
Thus, the outer surface layer of meteorite ALH84001 reached a high
temperature well above the blocking temperatures of its magnetic materials,
which caused the materials at the surface to realign with Earth's magnetic
field.
However, the interior portions of the slice were found to have randomly
oriented magnetization, which means that some of the materials inside the
meteorite never reached their blocking temperatures since sometime before
they left the Martian surface. Further, when the researchers gently heated
another slice taken from the interior of the meteorite, they discovered that
the interior of the rock started to demagnetize at temperatures as low as 40
degrees Celsius -- or 105 degrees Fahrenheit -- thus demonstrating that it
had never been heated even to that level.
Thus, a radiation-resistant organism able to survive without energy and
water for a year could have made the journey from Mars to Earth. Examples of
such hardy organisms, like the bacteria bacillus subtilis and deinococcus
radiodurans, are already well known.
"Realistically, we don't think any life forms more complicated than
single-celled bacterial spores, very tough fungal spores, or well-protected
seeds could have made it," Kirschvink says. "They would also have had to go
into some kind of dormant stage."
Though the study does not directly address the issue of life in meteorites,
the authors say the results eliminate a major objection to the panspermia
theory -- that any life form reaching Earth by meteorite would have been
heat-sterilized during the violent ejection of the rock from its parent
planet, or entry into the atmosphere. Prior studies have already shown that
a meteorite can enter Earth's atmosphere without its inner material becoming
hot.
"ALH 84001 has stimulated a remarkable amount of research to test the
hypothesis that life exists elsewhere than on Earth. The present study
indicates that the temperature inside the meteorite could have allowed life
to persist and possibly travel to Earth from Mars," says Nobel Prize-winning
biologist Baruch Blumberg, who is director of NASA's Astrobiology Institute.
The results also demonstrate that critical information could be lost if
rocks brought back from Mars by a sample return mission were
heat-sterilized, as has been proposed. Thermal sterilization would destroy
valuable magnetic, biological, and petrological information contained in the
samples.
If life ever evolved on Mars, it is likely to have jumped repeatedly to
Earth over geological times. Because the reverse process -- the transfer of
Earth life to Mars -- is dynamically much more difficult, it may be more
important to instead protect any Martian biosphere from Earthly microbes.
According to Kirschvink, "The Martian biosphere, if it ever evolved, would
most likely have been brought to Earth billions of years ago, and could have
participated in the evolution and diversification of bacterial life here.
"So there is at least a chance that we are in part descended from Martian
microbes," Kirschvink says.
The ALH84001 research was funded in part by NASA's Astrobiology Institute,
an international research consortium involving academic, non-profit and NASA
field centers, whose central administrative office is located at NASA's Ames
Research Center in California's Silicon Valley. A group from the Jet
Propulsion Laboratory in Pasadena, CA, which sponsored the Caltech research,
is one of the 11 lead teams of the institute.
Related Links
* Dr. Joseph Kirschvink
http://www.gpsdot caltechdot edu/faculty/kirschvink/
* The Division of Geological and Planetary Sciences at Caltech
http://www.gpsdot caltechdot edu/
* Martian Meteorite ALH84001
http://www.gpsdot caltechdot edu/tempfiles/magnetic_microscopy/
* NASA Ames Research Center
http://nai.arc.nasadot gov
[NOTE: Images supporting this release are available at
http://www.gpsdot caltechdot edu/tempfiles/magnetic_microscopy/]
==========
(6) MICRO-ORGANISMS FROM THE MOON?
>From Brig Klyce <bklyce@panspermia.org>
Russian biologists examining returned samples of lunar regolith have noticed
that some particles are fossilized microorganisms. Stanislav Zhmur and
Lyudmila Gerasimenko made the discovery when they took a careful new look at
Moon material returned in the 1970s by missions of the Soviet
Union's unmanned Luna program. The analysis was first published in December
1999, in the preceedings of an astrobiology conference (1).
At the same conference, these biologists reported fossilized microorganisms
in carbonaceous meteorites, and on 27 January, we publicized that finding
(3). Today, no one doubts that the meteoritic fossils are biological. But it
turns out that meteorites can easily become contaminated after contact with
the ground, so mainstream science now suspects that all fossilized
microorganisms in meteorites are the remains of recent contaminants. The
fossilized microorganisms from the Moon, however, were delivered to Earth in
sealed containers that were opened only in laboratories. They can hardly be
contaminants.
One striking circular fossil collected by Luna 16 bears an unmistakable
resemblance to modern spiral filamentous microorganisms like Phormidium
frigidum. Other particles returned by Luna 20 plainly resemble fossils of
modern coccoidal species like Siderococcus or Sulfolobus. These fossils are
solid evidence for ancient life beyond planet Earth.
References:
1. Stanislav I. Zhmur and Lyudmila M. Gerasimenko. "Biomorphic forms in
carbonaceous meteorite Alliende and possible ecological system - producer of
organic matter chondrites" in _Instruments, Methods and Missions for
Astrobiology II_, Richard B. Hoover, Editor, Proceedings of SPIE Vol. 3755
p. 48-58 (December 1999).
2. O.D. Rode, A.V. Ivanov, M.A. Nazarov, A. Cimbalnikova, K. Jurek and V.
Hejl. _Atlas of Photomicrographs of the Surface Structures of Lunar Regolith
Particles_, Prague, 1979.
3. "Fossilized Bacteria in Murchison and Efremovka," the Cosmic Ancestry
website, 27 January 2000.
* For the full story with three photos and links to references, see
"Microorganisms from the Moon," at http://www.panspermia.org/zhmur2.htm
(webpage not public until embargo expires)
Brig Klyce / Acorn Enterprises LLC
1503 Union Ave suite 200 / Memphis, TN 38104-3739
(901) 726-1111 / fax -0120
Cosmic Ancestry: http://www.panspermia.org
==========
(7) LEONIDS ON THE MOON
>From Rob McNaught <rmn@aaocbn.aaodot gov.au>
[as posted on the IMO mailing list]
I was too late to get the following note to Tony Phillips for his excellent
Science@NASA article at
http://www.spacescience.com/headlines/y2000/ast26oct_1.htm
Lunar Leonids: encounters of the Moon with Leonid dust trails.
Robert H. McNaught, Siding Spring Observatory
Last update 2000/10/27
The following table lists all encounters of the Moon with dust trails within
0.0010 AU during the current epoch. Only the trails discussed in ref [1]
are considered. The calculations are based on the formulae given in [2]. In
every year, a test date was used to derive the approximate magnitude of the
Moon's distance towards (-ve) or away from (+ve) the Sun in relation to the
Earth (rE-rM). This was then directly compared with values for dust trail
encounters with
the Earth given in [1] and close approaches were further investigated.
An iterative process is necessary, as the motion of the Moon during the tens
of minutes between Earth and Moon encounters with dust trails must be taken
into account.
The resulting time correction (dt) from the Earth encounter time in [1] is
given along with the distance of the nominal trail center from the Moon
(rM-rD).
Finally, an approximate ZHR indicates the relative activity of these
encounters. This is derived using the same form of analysis as in [1] and
can be compared with the predicted values for the Earth [3]. It seems clear
that 1999 was the year for lunar Leonids but the years 2000 and 2001 could
have some substantial activity.
It is notable that several of these encounters are unlikely to produce
meteor showers on the Earth, but as the Earth-Moon system is passing through
the midst of the comet 55P/Temple-Tuttle dust trail complex in 2000 and
2001, several encounters occur in each year for both the Earth and Moon.
The circumstance of resonant Leonids striking the Moon in 1998 may require
further examination. The 1333 trail is at a distance rE-rM = +0.0026 AU, so
it may not have been the culprit of the enchanced sodium tail. However,
another resonant trail may have passed closer to the Moon and I've asked
David Asher about this. David has noted that these old resonant trails are
broader than the young trails, so perhaps this greater miss distance is less
relevant. It is also the case that the greater mass of the particles in
these resonant trails could result in substantially more mass impacting the
Moon in 1998 despite this greater miss distance than the probable lunar
Leonid storm in 1999.
re-rm rm-rd dt Time of
AU trails AU min lunar max. "ZHR"
1997 Nov. 18.0 -0.0018 none
1998 Nov. 17.013 +0.0025 none
(20-rev +0.0026 -31)
1999 Nov. 18.089 -0.0009 3-rev +0.0002 +163 Nov. 18 04:51 UT 50,000
2000 Nov. 17.327 -0.0006 2-rev -0.0006 -175 Nov. 17 04:58 UT 1,000
18.156 -0.0002 8-rev +0.0010 -172 18 03:52 UT 10
18.327 -0.0001 4-rev +0.0009 -170 18 05:01 UT 50
2001 Nov. 17.595 +0.0022 1-rev 0.0000 +106 Nov. 17 16:03 UT 500
18.505 +0.0020 6-rev -0.0006 +128 18 14:16 UT 1,000
18.595 +0.0020 5-rev -0.0003 +130 18 16:28 UT 5,000
2002 Nov. 19.44 -0.0027 none
2003 Nov. 18.1 +0.0006 none
2004 Nov. 19.0 +0.0002 none
2005 Nov. 19.0 -0.0021 none
2006 Nov. 19.2 +0.0025 none
References
[1] R.H. McNaught, D.J. Asher, "Leonid dust trails and meteor storms",
WGN 27, 1999, pp. 85-102.
[2] R.H. McNaught, D.J. Asher, "Variation of Leonid maximum times with
location of observer", Meteorit. Planet. Sci. 34, 1999, pp. 975-978
[3] D.J. Asher, R.H. McNaught, "Expectations for the 2000 Leonids",
WGN 28, 2000, pp. 134-139
============================
* LETTERS TO THE MODERATOR *
============================
(9) NEW DEVELOPMENTS IN KANSAS FIREBALL STORY
>From Mark Kidger <mrk@ll.iac.es>
Benny:
Nice to see you back on the air again.
The Kansas fireball of October 13th hits the news again... You may remember
that NORAD were denying that it was space junk, despite ever-increasing
evidence that it was the Russian Proton booster of a Glonass (GPS) satellite
launch. Well, a surprised Kansas farmer has found the battered remains of
the rocket on his farm. I spoke to the WichitaEagle reporter who has been
covering this "UFO" story, she says that she is going to try and get a
comment from NORAD on the find.
Readers may find the following report interesting. This seems to settle the
case for once and for all.
http://meteors.com/cometlinear/locals_report_mysterious.html
Mark
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