PLEASE NOTE:
*
CCNet SPECIAL: BRITISH ASTRONOMERS MAKE HISTORY: LEONIDS
PREDICTION
CONFIRMED - 11 November 1999
QUOTE OF THE DAY
"The observed peak time coincides
almost perfectly with the peak
time of 2:08 am Greenwich Mean Time
predicted by Asher and
McNaught, indicating that the activity
was due to the dust trail
created the Leonids' parent comet,
Tempel-Tuttle, about 100 years
ago (i.e., 3 revolutions ago of the
Comet around the Sun)."
-- Marc Gyssens,
International Meteor Organization
18 November 1999
(1) BRITISH ASTRONOMERS MAKE HISTORY: LEONIDS PREDICTION
CONFIRMED
Benny J Peiser <b.j.peiser@livjm.ac.uk>
(2) LEONID METEOR STORM MATERIALIZES AROUND EXPECTED TIME
Marc Gyssens <mg@splut.urania.be>
(3) HUGE FIREBALL DAZZLES MIDWEST
Ron Baalke <baalke@ssd.jpl.nasa.gov>
(4) FIRST NIGHT OF LEONID MISSION SUCCESSFUL FOR ASTROBIOLOGISTS
NASANEWS <nasanews@mail.arc.nasa.gov>
(5) JUPITER'S CHILLY PAST
NASANEWS <nasanews@mail.arc.nasa.gov>
=============
(1) BRITISH ASTRONOMERS MAKE HISTORY: LEONIDS PREDICTION
CONFIRMED
From Benny J Peiser <b.j.peiser@livjm.ac.uk>
Britain woke up this morning to the usual lamentation about the
weather. What made things worse, however, was the fact that most
people
in the country weren’t able to enjoy the display of the
Leonids meteor
storm. Bad weather had hampered the view. Yet instead of moaning,
we
should celebrate a remarkable accomplishment by two young British
astronomers.
David Asher, an English astronomer based at the Armagh
Observatory
(Northern Ireland) and Robert McNaught, a Scottish astronomer
based in
Siding Spring Observatory (Coonabarabran, Australia) have made
history
by solving a scientific puzzle that has bewildered the
astronomical
community for exactly one hundred years: How to forecast the
seemingly
irregular Leonids meteor storms.
Ever since the widely predicted Leonids failed to appear in the
morning
of November 16, 1899, their erratic behaviour has been viewed as
somewhat of an enigma that seemed difficult to elucidate. Looking
back,
the unsuccessful prediction of 1899 led to a public relations
fiasco
for the astronomical community: "... the failure of the
Leonids to
return in 1899 was the worst blow ever suffered by astronomy in
the
eyes of the public, and has indirectly done immense harm to the
spread
of the science among our citizens." (Charles Olivier,
Meteors, 1925)
After one hundred years of endeavours to get a grip on the
capricious
Leonids, Asher and McNaught have pulled off a major success!
Their
prediction for the 1999 Leonids, based on their "dust trail
theory" has
been confirmed - at least regarding the exact timing of the peak
activity. McNaught & Asher predicted (see CCNet 10 November
1999) the
peak activity of the Leonids to occur this morning at about 2.08
am UT.
"For the 3-rev trail encounter in 1999, the time of maximum
is
predicted to be at Nov 18, 02:08 UT in the Mediterranean region,
with
an uncertainty of around 5 minutes. The time of maximum is
dependent on
location, with the peak predicted at 01:58 in South Africa and
02:14 in
northern Scandinavia."
As Marc Gyssens from the International Meteor Organization points
out
in the IMO press release (see below), the observed peak time
coincides
almost perfectly with the peak time of 2:08 am Greenwich Mean
Time
predicted by Asher and McNaught, "indicating that the
activity was due
to the dust trail created the Leonids' parent comet,
Tempel-Tuttle,
about 100 years ago (i.e., 3 revolutions ago of the Comet around
the
Sun)."
While this is an impressive confirmation of their theory, it is
interesting to note that their prediction of the highest hourly
rate
(Zenithal Hourly Rate, or ZHR), expected to be in the 500 range,
could not be validated: In fact, early reports suggest that the
peak
activity corresponded with an hourly rate up to ten times higher
than
the predicted number. Evidently, the Leonids never fail to
surprise us.
The historical achievement by Asher & McNaught should not be
depreciated by this minor drawback. What their success proves is
that
astronomical predictions are progressively improving. The time
will
come when we will be able to sufficiently understand, and
ultimately
yield control over, the dynamics of cometary and meteoric
activity that
affect our cosmic environment.
Well done, David and Rob!
Benny J Peiser
=================
(2) LEONID METEOR STORM MATERIALIZES AROUND EXPECTED TIME
From Marc Gyssens <mg@splut.urania.be>
I N T E R N A T I O N A L M E T E O R O R
G A N I Z A T I O N
Press release
Leonid meteor storm materializes around expected peak time
(UPDATE)
===================================================================
Experienced visual observers watching near Malaga and at the
Sierra
Nevada Observatory in Spain and near the Gorges du Verdon in the
French
Provence report that Leonid meteor activity peaked at up to 30
meteors
per minute shortly after 2 am Greenwich Mean Time. This activity
was
characterized by a lot of faint meteors and almost no fireballs.
Meteor astronomers reduce the actual numbers of meteors seen to a
standard value, called the Zenithal Hourly Rate (ZHR), which
takes
into account the quality of the sky as well as the direction from
which meteoroids enter the atmosphere. The peak activity reported
by
the abovementioned groups of observers corresponds with a ZHR
around
5000, which is considerably more than what most meteor observers
had
hoped for (around 1000).
Preliminary reports of other observing groups at Tenerife, Canary
Islands, near Valencia in Spain, and in Jordan confirm the
picture
sketched above.
Radio observations from Japan and the Czech Republic also
indicate a
peak time between 2:00 and 2:10 am Greenwich Mean Time.
The observed peak time coincides almost perfectly with the peak
time
of 2:08 am Greenwich Mean Time predicted by Asher and McNaught,
indicating that the activity was due to the dust trail created
the Leonids' parent comet, Tempel-Tuttle, about 100 years ago
(i.e., 3 revolutions ago of the Comet around the Sun).
Marc Gyssens
International Meteor Organization
Below is a more technical description of the observed Leonid peak
activity.
-------------------------------------
I M O S h o w e
r C i r c u l a r
-------------------------------------
LEONID Activity 1999
Visual observations of the 1999 Leonids revealed
a distinctive peak with a ZHR of about 5000 on
November 18, 2h05m +/-10m UT (solar longitude
235.287 +/- 0.007, eq. 2000.0). ZHR levels
were above 1000 from roughly 1h30m UT to 3h00m UT
corresponding to 235.26 to 235.32 degrees in solar
longitude.
All observers who were able to view the peak under good
sky conditions reported an abundance of faint meteors and
a relative absence of fireballs. Some observers noticed
a drop in the population index (i.e., a larger fraction of
brighter meteors) after the peak.
Reports from Mohammad Odeh (Jordanian Astronomical Society)
and Casper ter Kuile (Dutch Meteor Society, observing near
Valencia, Spain) are very consistent with the picture sketched
above.
In addition, radio data from K. Maegawa (Toyokawa Meteor
Observatory,
Aichi, Japan) reported by Kazuhiro Suzuki and the backscatter
radar data from Ondrejov Observatory (Czech Republic) reported by
Petr Pridal and Rosta Stork yield a peak time between 2h00m UT
and 2h10m UT.
It seems that the peak time of 2h08m UT predicted by
Asher/McNaught
is confirmed within a margin of at most a few minutes, although
the
observed activity is significantly higher. It is reasonable to
conclude that the peak activity has been caused by the
3-revolutions
old dust trail of 55P/Tempel-Tuttle.
The following observers have contributed data immediately
after the event, from which the ZHR profile given below
has been derived:
Per Aldrich, C.L. Chan, Asdai Diaz, Yuwei Fan, Fei Gao,
Lew Gramer, Andre Knoefel, Wen Kou, Alastair McBeath,
Tom Roelandts, Sirko Molau, Renke Song, Wanfang Song,
Honglin Tao, Dan Xia, Dongyan Zha, Jinghui Zhang, Yan
Zhang, Jin Zhu.
(For groups of observers, only the name of the contributing
observer has been mentioned.)
Date Period (UT) ZHR +-
---------------------------
Nov 17 0600-1000 16 2
Nov 17 1600-2010 30 5
Nov 17 1900-2200 53 14
Nov 18 0030-0100 130 90
Nov 18 0100-0115 490 230
Nov 18 0115-0130 770 160
Nov 18 0130-0145 1040 660
Nov 18 0145-0202 4100 840
Nov 18 0200-0215 5000 1100
Nov 18 0212-0230 2400 280
Nov 18 0243-0247 1100 160
Nov 18 0320-0330 470 70
Nov 18 0420-0430 180 40
---------------------------
ZHRs are computed with a population index of 2.0, zenithal
exponent of 1.0.
Marc Gyssens, 1999 November 18, 7h UT.
wgn@imo.net
=================
(3) HUGE FIREBALL DAZZLES MIDWEST
From Ron Baalke <baalke@ssd.jpl.nasa.gov>
Huge Fireball Dazzles Midwest
Marshall Space Flight Center
http://science.nasa.gov/newhome/headlines/ast17nov99_1.htm
November 17, 1999: Tuesday night, on an Illinois highway east of
Chicago,
traffic slowed to a crawl as motorists peered at an extraordinary
fireball
blazing overhead.
A brilliant fireball attracted stares across the eastern U.S.
Tuesday
night. It could be a taste of things to come when the Leonids
meteor
shower peaks late Wednesday night and Thursday morning.
"It was of the most beautiful meteors I have ever
seen," said Jamie
Dresser, who was driving home from work just after 6 pm CST.
"It was so
bright that it lit up the sky for quite a distance. There was a
blue
corona ... and it was actually trailing fire for quite a
distance. I
sincerely look forward to driving home the next few nights!"
Above: The above 533 KB QuickTime simulation illustrates the
relationship during the Leonids meteor shower between the earth,
comet
Tempel-Tuttle's dust field, and the constellation of Leo. The
size of
the earth and sun have been exaggerated for clarity. When the
earth
passes through Tempel-Tuttle's dust field every November 17-18,
the
dust particles stream into our atmosphere and burn up as meteors.
The
red arrow during the simulation indicates that a ground-based
observer
would perceive the meteors as coming from a point (called the
"radiant") within Leo, hence the name Leonids.
Hundreds of reports like this one are pouring in from all over
the mid
western United States. Thousands of commuters and star gazers saw
what
astronomers call an "Earth grazer" -- a meteoroid or
piece of space
debris that travels nearly parallel to Earth's surface as it
disintegrates in our atmosphere. Earth grazers are slow moving
and
feature vibrant colors in their long beautiful tails. This one
was
spotted between 5:50 and 6:05 CST as it sped over Wisconsin,
Michigan,
Illinois, Ohio, Kentucky, New York and several other states.
Tuesday night's fireball was so bright that it was first noticed
by
many observers while they were inside brightly lit buildings.
"I was sitting in a Wendy's facing outside and saw the
bright orange
light in the sky," recounts Wendi S. Abbott of Cincinnati,
OH. "I have
no idea how long it lasted, but I had time to jump up, race over
to the
window and ask the family sitting there if they were seeing what
I was
seeing. The father said it was just a reflection in the window,
but
quickly changed his mind. It finally broke apart in about 3 or 4
pieces
before it died out. What an incredible sight! If this is any
indication
of what's to come, this will definitely be a 'once in a lifetime
[experience]'."
The trajectory of the fireball was similar in appearance to an
aircraft, flying low and level across the horizon from west to
east.
Many observers reported seeing the meteor fragment into many
iridescent
pieces that traveled in a line like a string of Christmas lights.
Could this be a taste of things to come in the next 24 hours?
Possibly.
The Leonid meteor shower is expected to peak this Thursday
morning when
the Earth slices through the debris stream of comet Tempel-Tuttle
around 0200 UT on November 18. Last year a shower of Leonid
fireballs
(meteors brighter than magnitude -3) dazzled observers in Europe
and
the Americas. In 1999 many experts anticipate an even better
show. No
matter where you live, the best time to watch will be between
midnight
and dawn on Thursday. On Wednesday evening, November 17, before
the
constellation Leo rises, star gazers could be treated to more
Earth
grazers as Leonid meteoroids arc over the horizon.
With the Leonids just around the corner, it may seem surprising
that
Tuesday's fireball was probably not a Leonid. Leonid meteors
emanate
from a point in the sky within the constellation Leo, which rises
above
the eastern horizon around midnight. At the time of the fireball
sighting Leo was about 35 degrees below the northern horizon,
which
means that Leonid Earth-skimmers appearing over the horizon would
travel roughly north to south. Most observers reported that the
November 16 fireball moved west to east. While it is possible
that this
meteoroid was a part of the debris stream of comet Tempel-Tuttle
(the
parent of the Leonids), it is far more likely to be an unrelated,
sporadic meteor or perhaps a piece of "space junk"
decaying from
low-Earth orbit.
Whatever this fireball was, observers around the world have been
seeing
genuine Leonids for over 24 hours. The Leonids Environment
Operations
Center at the NASA/Marshall Space Flight Center is managing data
from a
global network of observers coordinated by the US Air Force and
the
University of Western Ontario. Since early Tuesday morning
trained
spotters have filed reports of 8 to 86 meteors per hour (ZHR). In
most
years, 86 meteors per hour would be considered a substantial
shower,
but this could be the year for a full-fledged Leonids storm. Only
time
will tell if predictions of more than 1000 meteors per hour will
come
true. One thing is sure, the place to be before dawn on Thursday
morning, November 18, is outdoors and looking up!
=================
(4) FIRST NIGHT OF LEONID MISSION SUCCESSFUL FOR ASTROBIOLOGISTS
From NASANEWS <nasanews@mail.arc.nasa.gov>
Nov. 17, 1999
Kathleen Burton
NASA Ames Research Center, Moffett Field, CA
(Phone: 650/604-1731, 650/604-9000) kburton@mail.arc.nasa.gov
Laura Lewis
NASA Ames Research Center, Moffett Field, CA
(Phone: 650/604-2162, 650/604-9000) llewis@mail.arc.nasa.gov
RELEASE: 99-74
FIRST NIGHT OF LEONID MISSION SUCCESSFUL FOR ASTROBIOLOGISTS
Astrobiologists began their first airborne observation night to
study
the Leonid meteors on Nov. 16, as the Earth began to enter the
debris
train left by the periodic comet 55P/Tempel-Tuttle.
At 21:50 GMT, on Nov. 16, the ARIA and FISTA, two United States
Air
Force planes, departed from Mildenhall in the United Kingdom for
Tel
Aviv Israel. During the overnight flight to Israel, the two
aircraft
flew approximately 80-100 miles apart from each other and as high
as
38,000 feet.
The mission flight path took the scientists southwest of
Mildenhall,
over Lands End and out of the United Kingdom. The aircraft
then
turned south to fly over north central Spain, and then turned
east to
fly over Barcelona. The flight continued over Corsica, across the
boot of Italy, over central Greece, and across the Mediterranean
into
Israel. ARIA and FISTA landed in Tel Aviv at 04:20 GMT Nov.
17.
The scientists and crew members aboard the FISTA and ARIA had a
very
successful first night of their Astrobiology mission. In addition
to
observing meteors, the team took measurements of air glow,
observed
and recorded lightning over Spain, and saw Jupiter and Saturn
clearly
in the night sky. They also successfully demonstrated that live
images of the meteors could be sent from the plane, over the TDRS
satellite, to the Internet.
The science team on the FISTA was thrilled with the collected
data.
"By the end of this first mission night we have already
exceeded the
number of meteors we observed with our mid-infrared instruments
during the entire 1998 mission over Japan," said Peter
Jenniskens,
Leonid mission chief scientist.
The mid-infrared spectrographs, contributed by the Aerospace
Corporation, are being used to detect the unique fingerprint of
complex organic matter - like that required for life - in
meteors.
The instruments are also expected to provide information on the
formation of solid particles and the heat of the meteors as they
enter the atmosphere.
"A total of 10 meteors crossed the field of view of our
spectrograph," reported George Rossano, a researcher on the
FISTA
aircraft. "I'm hopeful that these meteors will result
in the first
successful mid-infrared fingerprint of a meteor."
On ARIA, the flux measurement team counted meteors without
actually
looking out the window to see them; researchers wore goggles that
displayed images from cameras that were pointed out of the
airplane's
windows. The number of Leonid meteors and sporadic meteors
counted
by each team member was entered into a laptop computer.
Jane Houston, a member of the flux measurement team and one of
several amateur astronomers on the mission, explained how the
team
differentiated between Leonid and sporadic meteors. "The
Leonid
meteors radiate from the constellation Leo, while sporadic
meteors
fall randomly across the sky."
Each of the team members' laptop computers was linked to a
central
laptop computer, and near real-time data indicating the total
number
of meteors counted was provided. "The methods developed to
count
meteors for this mission could revolutionize the way future
meteor
showers are monitored," claimed Kelly Beatty, another
amateur
astronomer on the flux measurement team.
At the end of the night, the flux team reported observing
approximately 14 sporadic meteors per hour and a Leonid zenith
hourly
rate of approximately 15 meteors per hour. The zenith hourly rate
is
the number of meteors an observer on the ground would see under
perfect observing conditions.
"These rates for Leonids are almost twice as high as those
we would
normally see the night before the expected peak," explained
Dr.
Jenneskins, "I'm optimistic this is an indication that we
will see a
good storm tomorrow night."
The peak of the Leonid storm is expected at 02:00 GMT Nov. 18
over
Europe and the Middle East. The international science team
studying
the Leonids will be flying from Tel Aviv to Lajes Airbase during
the
storm peak. It may be possible to see the Leonid meteor storm in
the
United States on the night of Nov. 17 (9:00 p.m. EST).
However, best
viewing may actually be in the predawn hours of Nov. 18.
The Leonid Multi-instrument Airborne Campaign is an Astrobiology
mission from NASA Ames Research Center at Moffett Field,
CA. The
campaign is jointly funded by the United States Air Force and the
National Aeronautics and Space Administration. Astrobiology is an
interdisciplinary field that studies the origin, evolution,
distribution and destiny of life in the universe.
For current information about the Leonid Multi-instrument
Airborne
Campaign, and to watch live Leonid coverage on the Internet,
visit:
http://leonid.arc.nasa.gov/
================
(5) JUPITER'S CHILLY PAST
From NASANEWS <nasanews@mail.arc.nasa.gov>
Nov. 17, 1999
Kathleen Burton
NASA Ames Research Center, Moffett Field, CA
(Phone: 650/604-1731, 650/604-9000) kburton@mail.arc.nasa.gov
Jane Platt
Jet Propulsion Laboratory, Pasadena, CA
(Phone: 818/354-0880) jane.platt@jpl.nasa.gov
RELEASE: 99-75
GALILEO PROBE RESULTS SUGGEST JUPITER HAD AN ANCIENT, CHILLY PAST
Jupiter's history may be much older and colder than previously
believed, according to newly released findings from the descent
probe
of NASA's Galileo spacecraft published in the Nov. 18 edition of
the
journal Nature.
"This new information might shake up our view of how the
solar system
formed," said Dr. Tobias Owen, astronomy professor at the
Institute for
Astronomy of the University of Hawaii, Honolulu, HI, and a
scientist on
the Galileo probe neutral mass spectrometer instrument
team. When
Galileo arrived at Jupiter on Dec. 7, 1995, and dropped a probe
into
the atmosphere of the huge, gaseous planet, the mass spectrometer
measured the chemical composition of Jupiter's atmosphere.
The spectrometer detected in Jupiter's atmosphere higher than
expected
concentrations of argon, krypton and xenon, three chemical
elements
called noble gases because they are very independent and don't
combine
with other chemicals. Tiny traces of these gases are found in
Earth's
atmosphere, and argon is sometimes used like neon in advertising
signs.
The discovery of these gases in such high quantities at Jupiter
raises
questions about how they got there. "In order to catch
these gases,
Jupiter had to trap them physically by condensation or
freezing," Owen
said. This process, he said, requires extremely cold
temperatures of
about -240 degrees Celsius (-400 degrees Fahrenheit), colder than
the
surface of Pluto, the planet farthest from the Sun. Planetesimals
(small objects orbiting the Sun) in the Kuiper Belt beyond Pluto
would
be this cold, but Jupiter is more than six times closer to the
Sun and
thus is much warmer. For this reason, Jupiter could not
have been the
site where the three noble gases were originally trapped.
"This raises some intriguing possibilities," Owen said.
"One
explanation suggests that Jupiter was formed out in the area
around the
Kuiper Belt and dragged inward to its present location. Another
possibility is that the solar nebula, a huge cloud of gas and
dust from
which our solar system formed, was much colder than scientists
believe," he said. -more-
"A third hypothesis proposes that the solid materials that
brought
these noble gases to Jupiter began forming in the original huge,
interstellar cloud of gas and dust even before it collapsed to
form the
solar nebula. That would make these icy materials older and more
primitive than we had expected," he said.
"If either of the last two hypotheses proves to be correct,
it would
suggest that giant planets can form closer to their stars than
current
theories predict," Owen said. "This could help
explain the new
observations of planetary systems around other stars, in which
such
close-in giant planets are relatively common."
"These new Galileo probe results provide new insights into
how planets
form in the solar system and around other stars," said
Galileo project
scientist Dr. Torrence Johnson of NASA's Jet Propulsion
Laboratory,
Pasadena, CA.
"Measuring the composition of Jupiter's atmosphere was a
primary
scientific objective of the probe, because we knew it could
change our
understanding of Jupiter's formation and evolution," said
Galileo probe
project scientist Dr. Richard Young of NASA Ames Research Center,
Moffett Field, CA. "These latest probe results have done
exactly that,
and the measurements are the sort that could only have been
obtained by
in-situ measurements from an entry probe."
Owen's co-authors on the Nature article are: Drs. Paul Mahaffy
and
Hasso Niemann of NASA's Goddard Space Flight Center, Greenbelt,
MD;
Drs. Sushil Atreya and Thomas Donahue of the University of
Michigan,
Ann Arbor, MI; Dr. Akiva Bar-Nun of the University of Tel Aviv,
Israel;
and Dr. Imke de Pater of the University of California, Berkeley,
CA.
Although the data were collected by the Galileo probe in December
1995,
careful and thorough analysis was necessary in Earth laboratories
to
verify the findings.
When it dropped 156 kilometers (97 miles) through Jupiter's
atmosphere,
the Galileo probe relayed data back to the main Galileo
spacecraft more
than 209,215 kilometers (130,000 miles) overhead for storage and
transmission to Earth. The probe descended deeper into the
atmosphere
than expected, but was finally overcome by Jupiter's high
temperatures
and pressures.
The Galileo spacecraft, meanwhile, has been orbiting Jupiter and
its
moons for nearly four years, beaming back to Earth thousands of
pictures and a wealth of scientific data. Its two-year, primary
mission
ended in December 1997, but it was followed by the current,
two-year
extended mission. The Galileo Project is managed by the Jet
Propulsion
Laboratory, Pasadena, CA; the Galileo atmospheric probe is
managed by
NASA Ames Research Center, Moffett Field, CA. Further
information and
images about the Galileo mission to Jupiter are available on the
Internet at:
http://www.jpl.nasa.gov/galileo
----------------------------------------
THE CAMBRIDGE-CONFERENCE NETWORK (CCNet)
----------------------------------------
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subscribe/unsubscribe,
please contact the moderator Benny J Peiser <b.j.peiser@livjm.ac.uk>.
Information circulated on this network is for scholarly and
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or
reproduced for any other purposes without prior permission of the
copyright holders. The fully indexed archive of the CCNet, from
February 1997 on, can be found at http://abob.libs.uga.edu/bobk/cccmenu.html
*
THE "TORINO SCALE" AND THE IAU
From Johannes Andersen <ja@astro.ku.dk>
The character and purpose of the so-called "Torino
Scale" and its
"adoption" by the IAU has been the subject of some
recent discussion on
CCNet. While we cannot endeavour to correct every
misunderstanding
arising in the grey literature, it seems useful to provide a
clarification here.
From our point of view, the Torino Scale is a useful concept in
dealing
with the public and the media for two reasons. First, it
highlights the
vast range of consequences associated with impacts of different
magnitude, all of which are possible at equally different, if all
microscopic levels of probability. And second, it immediately
makes the
point that no known NEO presents any measurable danger to Earth
in the
foreseeable future.
As such, it is a great improvement over the concept of
"Potentially
Hazardous Asteroids" (PHAs), which was useful when orbit
computation
methods were less refined and anything approaching was
potentially
dangerous. At the current state of the art all PHAs are Perfectly
Harmless Asteroids, and the old interpretation of the acronym is
misleading to the public.
In a semi-scientific context, the Torino Scale is also useful in
conveying the message to the public that the offer of IAU peer
review
extends to any discovery of an NEO that is not patently harmless.
Exactly how the experts decide what is what is a concern for
those
experts. As a package, the review mechanism and the Scale are a
real
contribution to the professional handling of both the scientific
and
political aspects of NEO discoveries by the international
community,
negotiated by the IAU Working Group on NEOs. We find this result
to be
a credit to the IAU, and the public deserves to know that the
Union is
acting responsibly on this sensitive issue.
In a purely scientific context, a classification scheme that
places all
known objects in Category 0 is, of course, not exactly a
breakthrough.
As knowledge progresses, we shall no doubt see either a revision
(or
several) of the Torino Scale, or the development of more refined
schemes, based on the rich variety of orbital data that are now
becoming available. This will go on happily within the IAU NEO
community as a continuing process as scientific frontiers expand.
Attempts to interpret the IAU "adoption" of the Scale
as explained
above as a sanctification of every technical aspect of its first
incarnation or as an iron rule on its use in scientific studies
of NEOs
is, first, misguided, and second, doomed to failure in the real
world
of science - the home territory of the IAU.
Johannes
Andersen
Hans Rickman
General Secretary,
IAU
Assistant General Secretary, IAU
==============================================================
IAU/UAI Secretariat
Institut
d'Astrophysique
Tel: +33 1 4325 8358
98bis, Bld.
Arago
Fax: +33 1 4325 2616
F - 75014
Paris
E-mail: iau@iap.fr
France
WWW: http://www.iau.org/
==============================================================