PLEASE NOTE:
*
CCNet 114/2000 - 8 November 2000
--------------------------------
"I read few books, but I absorb many. They hurtle towards me
each
week like asteroids. They are dodged or read on impact, each one
disturbing my mental orbit. The book remains the most influential
means of communication. It is a book that recounts life in the
Blair court
or the Royal Family. A book is a politician's apologia and a
celebrity's
dread. The kiss- and-tell memoir, the cookery blockbuster or the
Spice Girl spin-off is always a book. Nothing else so changes
ideas or
religions. No website, newsclip or documentary beats the book.
This
noble manufacture is infinitely portable, infinitely accessible
and
infinitely enduring."
-- Simon Jenkins, The Times, 8 November 2000
"Last Saturday a syndicated sports-writer compared LA Lakers
center
Shaquille O'Neal to 2000 SG344, a newly-discovered near-Earth
object
(NEO). During Shaq's game the night before, O'Neal had barreled
into the
opposing center "like 2000 SG344 -- that object hurtling
toward
Earth." Fortunately for basketball fans, O'Neal is far more
likely to score
a free throw than 2000 SG344 is to crash land on our planet.
Although SG344
is nearby now, scientists say there is no appreciable chance of a
collision
for at least 70 years. (Shaq, on the other hand, should make
plenty of
baskets between now and then.)"
-- NASA News, 7 November 2000
(1) MUCH ADO ABOUT 2000 SG344
NASA Science News <snglist@lyris.msfc.nasa.gov>
(2) SHOEMAKER BY LEVY: THE MAN WHO MADE AN IMPACT
Larry Klaes <lklaes@BBN.COM>
(3) 1991 VG & 2000 SG344
Gonzalo Tancredi <gonzalo@fisica.edu.uy>
(4) IMPACT RISK DATA SHOULD NOT BE WITHHELD
Bev M Ewen-Smith <coaa@mail.telepac.pt>
(5) WHY THE IAU GUIDELINES SHOULD BE CHANGED
Benny J Peiser <b.j.peiser@livjm.ac.uk>
(6) MANAGING THE MEDIA TO OUR MUTUAL ADVANTAGE
Simon Mansfield <simon@spacer.com>
(7) ASTEROID SCARE IN THE GERMAN MEDIA
Christian Gritzner <christian.gritzner@mailbox.tu-dresden.de
(8) FEWER GLOBAL WARMING ITEMS ON CCNET, PLEASE
Mike Barlow <mjb@star.ucl.ac.uk>
==========
(1) MUCH ADO ABOUT 2000 SG344
From NASA Science News <snglist@lyris.msfc.nasa.gov>
http://science.nasa.gov/headlines/y2000/ast06nov_2.htm
In 2071 a relic of NASA's earliest space exploration efforts
might return to
Earth, if current estimates are confirmed. [NOW, that's
what I call a
classic! Which begs the question: 6hy wasn't this hillarious spin
put on the
initial 2030 announcement? BJP]
Much Ado ab7ut 2000 SG344
NASA Science News, 7 November 2000
November 7, 2000 -- Last Saturday a syndicated sports-writer
compared LA
Lakers center Shaquille O'Neal to 2000 SG344, a newly-discovered
near-Earth
object (NEO). During Shaq's game the night before, O'Neal had
barreled into
the opposing center "like 2000 SG344 -- that object hurtling
toward Earth."
Fortunately for basketball fans, O'Neal is far more likely to
score a free
throw than 2000 SG344 is to crash land on our planet.
Although SG344 is nearby now, scientists say there is no
appreciable chance
of a collision for at least 70 years. (Shaq, on the other hand,
should make
plenty of baskets between now and then.)
2000 SG344 was discovered by asteroid-hunters on Sept. 29th as it
was
gliding by Earth approximately 20 times farther away than the
Moon.
Astronomers quickly realized that the faint object was unusual.
Its 354 day
orbit is very much like Earth's, so much so that 2000 SG344 might
not be an
asteroid at all, but rather a piece of manmade rocket debris.
Our planet and 2000 SG344 move through space like two runners
racing along a
track at nearly the same speed; it takes a long time for one to
lap the
other. The NEO, which is moving a bit faster than Earth, is
slowly drifting
away and won't return for 30 years.
As recently as last Friday astronomers were concerned that the
next
encounter might be too close for comfort. A panel convened by the
International Astronomical Union (IAU) announced on Nov. 3rd that
2000 SG344
might hit Earth in the year 2030. The chances of an impact were
slim, they
said, and new data to refine the object's orbit would likely rule
out a
collision altogether.
That's exactly what happened. Shortly after the IAU announcement,
astronomer
Carl Hergenrother found "pre-discovery" images of 2000
SG344 from May 1999
in archives from the Catalina Sky Survey.
"The pre-discovery images let us calculate a better orbit
that absolutely
rules out a collision in 2030," says Donald Yeomans, manager
of NASA's Near
Earth Object program at the Jet Propulsion Laboratory. "It
won't come any
closer to Earth than 11 lunar distances. However," he added,
"the new orbit
increases the chances of encounters in years after that. For
example, there
is a 1-in-1000 chance of a collision on Sept. 16, 2071."
Just as the possible 2030 encounter was excluded by better data,
Yeomans
anticipates the same will happen to the 2071 date.
"Additional observations
this year and in 2030 when SG344 comes back again will certainly
alter our
conclusions as we learn even more about its orbit."
If Earth and 2000 SG344 do cross paths in the future, what
happens will
depend on the nature of the near-Earth object. When the object
was first
discovered it appeared to be a small asteroid, but another
possibility is
gaining favor among researchers. "The orbit of SG344 is so
Earth-like, it
makes you wonder if came from our own planet," mused
Yeomans.
In 1971, the last time 2000 SG344 was in the vicinity of Earth,
NASA's
Apollo program was in full swing. 2000 SG344 may well be debris
from an
Apollo-era rocket masquerading as a space rock.
"Initially we thought it was too bright (and thus too large)
to be a rocket
fragment, but it's possible that this is the S-IVB stage from a
big Saturn
V," continued Yeomans. "S-IVBs" were booster
rockets that propelled Apollo
Command and Service Modules toward the Moon from their parking
orbits around
Earth. "Many of those boosters were targeted to hit the
Moon, but the S-IVBs
from Apollo 8 through 12 went into orbit."
If SG344 is a derelict rocket booster, it's probably no larger
than 15
meters and wouldn't pose much of a threat even if it did strike
Earth. An
incoming S-IVB would burn up in the atmosphere as a dazzling but
mostly-harmless fireball. Spectators in Texas and Oklahoma
witnessed just
such a display last month when the casing from a Russian Proton
rocket
disintegrated over North America.
On the other hand, if 2000 SG344 is a bona fide space rock, it's
likely to
be bigger and more dangerous. Typical near-Earth asteroids
reflect about 3%
to 20% of the sunlight that falls on them. The apparent
brightness of 2000
SG344 corresponds to such an asteroid 30 to 70 meters across.
"Whatever it is, 2000 SG344 is certainly no dinosaur
killer," Yeomans added,
referring to a 10 km space rock that may have triggered mass
extinctions
when it hit Earth 65 million years ago. A 70-meter asteroid (the
worst-case
scenario for 2000 SG344) could obliterate a city if it landed on
one, but it
would not trigger a global catastrophe.
At the lower end of the scale, around 30 meters, 2000 SG344 might
not even
reach the ground. "It depends on what it's made of,"
says Yeomans. "A
30-meter slab of iron could make it through the atmosphere and do
some local
damage." On the other hand, a fragile carbonaceous chondrite
like the
widely-publicized Yukon fireball of January 2000 would mostly
disintegrate
high overhead.
The September discovery of 2000 SG344 by astronomers David Tholen
(University of Hawaii) and Robert Whiteley (now with the Catalina
Sky
Survey) was no accident. Using the Canada-France-Hawaii telescope
atop Mauna
Kea, the pair were looking for unusual near-Earth asteroids in
orbits whose
greatest distance from the Sun coincides with the Earth's orbit.
Such
objects could hit our planet, but they would rarely be found by
search
programs that hunt for space rocks coming from the general
direction of the
main asteroid belt.
"We're not doing a full-fledged survey like LINEAR,
Spacewatch, or LONEOS,"
says Tholen. "We observe only a few nights each year."
Nonetheless, the pair
have discovered ten near-Earth objects since they began their
part-time hunt
in 1996. Their most celebrated find, 2000 SG344, is technically
classified
as an "Aten": an Earth-crossing object with an orbital
semi-major axis
smaller than one astronomical unit. Atens spend most of their
time inside
Earth's orbit, crossing over for brief intervals only.
But is 2000 SG344 an Aten asteroid or an Aten rocket shell?
That's the
10-megaton question.
Tholen thinks it may be an asteroid. "The only Apollo
launches in 1971 (the
last time 2000 SG344 was close to Earth) were Apollo 14 and 15.
But the
S-IVB stages from those missions crashed into the Moon."
"The wild card is Apollo 12," he continued. "Its
S-IVB stage apparently
wound up in an Earth-circling orbit. There is a possibility that
the Moon
perturbed Apollo 12's S-IVB into an orbit around the Sun."
In that case, the
important time is not when Apollo 12 launched in 1969, but
instead when the
Moon might have nudged the booster into its new orbit."
"Another problem [in assessing the rocket hypothesis] is
that we don't know
what happens to white paint after 30 years of micrometeoroid
bombardment,"
says Tholen. Does it remain white, or would the paint erode,
revealing a
less reflective surface beneath? "We have to guess at the
reflectivity to
convert the measured brightness into a diameter estimate and
those diameter
estimates seem too big to be an S-IVB. We do have evidence in the
images of
a rapidly rotating (about 10 minute period) elongated (maybe 2 to
1) object.
That sure sounds like the shape of a Saturn booster, but we've
also found
asteroids that match that description!"
Whatever it is, astronomers plan to track SG344 as it slowly
recedes from
Earth -- more data will reduce the uncertainties about SG344's
orbit and
naturally answer many of the questions about this mysterious NEO.
But there's not much time. The orbit of 2000 SG344 is carrying it
toward the
blinding glare of the Sun. By mid-2001, the object will be dimmer
than 25th
magnitude as its solar elongation dips below 90 degrees.
"That's a tough
combination for observers," noted Yeomans. "We might
find more pre-discovery
images," he added hopefully. "Pictures from 1971 would
really lock down the
orbit and probably tell us whether SG344 is a rocket or an
asteroid. We just
have to keep looking."
===============
(2) SHOEMAKER BY LEVY: THE MAN WHO MADE AN IMPACT
From Larry Klaes <lklaes@BBN.COM>
History of Science and Medicine, Philosophy of Science
Physics and Astroscience
Geological Science
We are pleased to send you the following information about this
newly
published book:
Shoemaker by Levy
The Man Who Made an Impact
David H. Levy
http://pup.pupress.princeton.edu/titles/6909.html
It was a lucky twist of fate when in the early 1980s David Levy,
a writer
and amateur astronomer, joined up with the famous scientist
Eugene Shoemaker
and his wife, Carolyn, to search for comets from an observation
post on
Palomar Mountain in Southern California. Their collaboration
would
lead to the 1993 discovery of the most remarkable comet ever
recorded,
Shoemaker-Levy 9, with its several nuclei, five tails, and two
sheets of
debris spread out in its orbit plane. A year later, Levy would be
by the
Shoemakers' side again when their comet ended its
four-billion-year-long
journey through the solar system and collided with Jupiter in the
most
stunning astronomical display of the century. Not only did this
collision
revolutionize our understanding of the history of the solar
system, but it
also offered a spectacular confirmation of one scientist's life
work. As a
close friend and colleague of Shoemaker (who died in 1997 at the
age of 69),
Levy offers a uniquely insightful account of his life and the way
it has
shaped our thinking about the universe. This biography shows what
Shoemaker's
legacy will be for our understanding of the story of the Earth
well into the
twenty-first century.
David H. Levy has discovered twenty-one comets, eight of them
using his own
backyard telescope. Science Editor for Parade magazine, he also
writes the
monthly "Star Trails" column in Sky and Telescope. Levy
is the author of
many books relating to astronomy, from beginners' observing
guides to such
recent popular accounts as Comets: Creators and Destroyers. He
has written
two other scientific biographies: The Man Who Sold the Milky Way:
A
Biography of Bart Bok and Clyde Tombaugh: Discoverer of Planet
Pluto. Levy's
awards include an Emmy for his role in writing the 1997 Discovery
Channel
documentary Three Minutes to Impact.
0-691-00225-8 Cloth $27.95 U.S. and L17.50 UK
320 pages, 39 halftones, 2 tables, 6 x 9.
Visit our sale catalog on-line at:
http://pup.pupress.princeton.edu/sale.html
============================
* LETTERS TO THE MODERATOR *
============================
(3) 1991 VG & 2000 SG344
From Gonzalo Tancredi <gonzalo@fisica.edu.uy>
[as posted on mpml@egroups.com]
Regarding the origin of 1991VG, I would like to point out a paper
I
published a few years ago about the subject. In that paper I
discuss the
different possible origins: coming from the main belt, a man made
object and
ejecta from the Moon. I favor the last one.
The paper was published in Celesteial Mechanics v 69 p 119-132
The title is: "An Asteroid in a Earth-like Orbit" , G.
Tancredi.
The abstract reads as following:
"The dynamical evolution of an asteroid with orbital
elements strikingly
similar to the Earth is analysed. The object, 1991 VG, was
discovered by the
Spacewatch telescope during a particular encounter with the
planet. 1991 VG
experienced a temporary satellite capture by the Earth, a
phenomena that is recurrent in its dynamical history. The
possible origin of
this puzzling object is discussed, including the suggestion that
1991 VG
could be a piece of lunar ejecta after a great impact."
A preprint could be find in:
http://www.fisica.edu.uy/~gonzalo/listpub.html
A similar analysis could be done for 2000SG344. The problem is
that this
object seems to be 3 time bigger in diameter.
Gonzalo Tancredi
Dpto.
Astronomia
Tel : (598-2) 525 86 24/25/26 int. 319
Facultad
Ciencias
Fax : (598 2) 525 05 80
Igua
4225
Email : gonzalo@fisica.edu.uy
11400 Montevideo - URUGUAY http://www.fisica.edu.uy/~gonzalo
===============
(4) IMPACT RISK DATA SHOULD NOT BE WITHHELD
From Bev M Ewen-Smith <coaa@mail.telepac.pt>
Dear Dr Peiser
I have to say that I consider your remarks, quoted in the press,
to be part
of the problem, rather than part of the solution.
It would be a much better service to the NEO community to put the
record
straight when journalists go off the deep end, by saying that
"the risk is
x% on the basis of the information available today" and on
the following
day, "the risk is now y% on the basis of more
information"; where y is less
than x in this case. There is nothing inconsistent in those two
statements
and no need to talk of a 'volte-face' or 'changed their minds'.
It would
have been very much better for you to have said **that** in
print, than to
have taken the opportunity of self-aggrandisement by criticizing
others
working to an agreed methodology.
I am absolutely baffled that you are seriously talking about
withholding
information - be it from the press or the wider astronomical
community -
until .... what? The final 100% confirmation of an impact occurs
only after
the event - who knows what cosmic billiards might do for us at
the 11th
hour, for example. Any information of this sort **must** be
freely available
and serious political implications arise from any attempts to
suppress it.
What we need is **more** information, including a reasoned
explanation of
what it means and how the position is likely to evolve over time.
God forbid
that we do anything to feed the paranoia of conspiracy theorists.
Suggesting that a limited mailing of confirmation observatories
would keep
such things from the press. This surely is nonsense - many
journalists are
mind-bogglingly stupid but there are so many paths out for such
information
that a full and detailed disclosure *must* be better than
leaks.
I suppose by the same token you would advoke not mentioning a
hurrican in
Florida, or even the possibility of gales in the South of
England, in a
weather forecast just in case subsequent synoptic observations
suggested it
might turn out to be just a breeze.
To use *authority* to attempt to control what appears in the
press, even in
the name of accuracy (according to an assumed authority) is,
frankly,
totalitarianism. I think we are better off with press nonsense
than with
that.
Bev
=============
(5) WHY THE IAU GUIDELINES SHOULD NOW BE CHANGED
From Benny J Peiser <b.j.peiser@livjm.ac.uk>
Bev,
Why should I support flawed IAU guidelines which have caused yet
another
embarrassment to all of us involved in the NEO research
community? Please
note that I did draw the attention of the WGNEO to mistakes made
with past
impact announcements months ago. I also suggested a number of
changes which
I thought were needed in order to avoid future fiascos. Here is
what I wrote
in a report sent to the members of the IAU WGNEO on 24 March
2000:
"As early as June 1999, in the context of the OX4
announcement,
Brian Marsden already warned [impact risk] announcements
[...] might soon
become counterproductive (see: CCNet, 14 June 1999,
http://abob.libs.uga.edu/bobk/ccc/cc061499.html).
"If we direct our
attention to intrinsically fainter objects, more and more cases
of
noticeable impact probabilities will surely be found. [...] While
there is
clearly merit to following up PHAs, as well as other NEOs, both
astrometrically and physically, with too many computations of
non-zero
impact probabilities from short-arc orbits, there is the danger
of going on
too many wild-goose chases, with unnecessarily large efforts
(including
"peer review" recomputations of the impact
probabilities by others) expended
on objects that turn out, not only not to be any threat to the
earth during
the foreseeable future, but not even to be particularly
interesting."
These warnings went largely unheaded. No wonder then that more of
Marsden's
predicted "wild-goose chases" and premature
announcements were to follow.
[...] The problems with the handling of BF19 have made clear,
once again,
that there is still a major problem with regard to the
dissemination
of information about such PHAs. Clearly, the important thing is
to ensure
that the information is available to astronomers who are in a
position to
confirm or deny the calculation, by means of new,
post-announcement
observations, through the recognition of images on archival
photographs, or
both. The question is how this can be best achieved. Regrettably,
the WGNEO
has failed to tackle this problem for much of the last two years.
Some members of the IAU WGNEO instead believe that the underlying
problem is
that of "peer review". In other words, other
astronomers should verify the
*mathematical calculations* of such cases. But this is quite
clearly a red
herring, given that none of the five cases of "virtual
impactors" resulted
from computational flaws. The real mistake that has been made, in
every(!)
single case, was in the way information about essentially correct
computations was either inappropriately worded or wrongly
circulated or
both.
For better or for worse, and mainly for the latter, this failure
in properly
communicating with astronomers has resulted in unnecessary
involvement of
the public, on each of the five occasions. This is where the
author of this
report, in his role as CCNet moderator, accepts his own mistakes
and
responsibility.
As a direct consequence of the BF19 events, I have decided that I
will no
longer forward hypothetical impact probability calculations on
CCNet as long
as the object in question can be eliminated as a potential threat
by further
observations of a still visible object.
From a positive perspective one could legitimately argue that the
past
mistakes, nevertheless, have to some degree helped to 'educate'
and
enlighten astronomers, science journalists and the interested
public about
the inherent problems of dealing with such objects. However, in
three of the
five cases, the potential hazard could be eliminated from the
list of
worries within days, if not hours, of the announcements.
On 18 February, in addition, Andrea Boattini and colleagues
identified an
image of 2000 BF19 on a Palomar photograph taken on 4 October
1991. This
image was even more useful in determining the orbit than the
later
observations. Of course, one can never be sure that old images
will
resurface, but this has happened now for three of the five
"impact" cases of
the the past two years. Clearly it's a problem more for the
intrinsically
fainter objects, like 1998 OX4, although with the postdiscovery
orbit so
weak in that case, it would be difficult to find old
prediscoveries even if
they existed.
The BF19 asteroid scare, based on an object with an extremely
short-arc
orbit, and its retraction less than 24 hours later has
demonstrated again
that we have still not learned any lessons from past mistakes and
embarrassments. It is time that these blunders are not repeated
again."
--------
Now this was back in March. Regrettably, my attempt was to no
avail.
Nevertheless, I still hope that common sense will prevail and
effective
changes to the IAU procedures will now be implemented.
As I made clear in no uncertain terms yesterday, I do *not*
advocate
withholding any information about potential impact risks. Quite
the
opposite! This data needs to be published quickly and wide in the
open so
that everyone has access to it. In fact, it was exactly this
failure to
*inform* observers widely and early on that caused the latest
mishap. If
observers know nothing about a potential impactor they simply
cannot provide
additional data which, in almost all cases, will eliminate the
threat.
Instead, under the current guidelines, the IAU and its technical
team of NEO
experts are forces to keep potential impact risks that score
above level 1
on the Torino Scale *secret* from the public for 72 hours.
According to the
guidelines, a public IAU statement will follow automatically if,
after this
period of time, no additional data has come forward to eliminates
or reduce
the impact probability. This is what happened with SG344.
HOWEVER: There is absolutely no need to stage a news conference
or issue an
international press release every time we find another potential
impactor
that cannot be eliminated within 72 hours! Instead, both
the observational
data and additional explanatory information should be immediately
published
on a website (or websites) that are mainly addressed at the NEO
search
community. As long as observers can add data to the orbital
certainty of a
potential impactor, i.e. as long as the object can be observed,
nobody
should be forced to make an public announcement. Only in those
cases, which
I suppose will be rare, that a newly discovered "virtual
impactor" is lost
for years to come, an IAU statement might be required.
These are, of course, only suggestions for the current discussion
that is
taking place within the IAU and its WGNEO. It might be helpful, I
feel, if
some of these debates and proposals which are aimed at improving
IAU
procedures would also take place in the open.
Benny J Peiser
===============
(6) MANAGING THE MEDIA TO OUR MUTUAL ADVANTAGE
From Simon Mansfield <simon@spacer.com>
Benny,
Despite all the criticism - name one person on the planet who is
disappointed that the astronomers got it wrong and that there
will be no
impact this time around.
The danger of impacts is now firmly etched on the media's
runsheet of good
story ideas. Meanwhile, the public is becoming more and more
aware that
these things exist and do occasionally impact us.
It's up to scientists in individual countries to grab hold of
opportunities
like this to further educate the media.
For example, in Australia, the real issue is the lack of support
by our
government for the Southern Sky Survey program, and that what
money is
available has come from NASA as part of a small joint program
with one of
the main observatories here.
Given that Australia is the richest, most advanced nation in the
Southern
Hemisphere we should surely be able to come up with several
million dollars
a year to fund a thorough search of the Southern Hemisphere sky -
it been
50% of the sky and all that.
This is the issue our local astronomers should be getting out to
the media
at times like this, and the same is true for South America, where
collectively the bigger nations could pool funds of 2 million or
so to fund
a new program at ESO and the other fabulous observatories in
Chile etc.
In regards to the issuing of warnings etc, the process maybe
should involve
an advisory sent to a very tight list of centers that maintain
substantial
records that can be used in the initial pre discovery search
phase.
If after an initial pass no pre discovery data is found, a second
advisory
could be issued requesting a high priority search be done of any
and all
records that could be used to find pre discovery data.
Depending on whether the object in question will orbit safely
before a
dangerous encounter occurs could be used to decide our public
this high
priority search be made.
The Torrino scale may need a sibling scale that determines the
priority of a
warning being issued based on the number of years and orbits to a
dangerous
encounter.
Moreover, with a better media management strategy the whole pre
discovery
search process could be the media event itself. The actual
process of sky
cataloguing, pre discovery searches etc involves a lot of people
throughout
the world, with the added dose of big number crunching and other
gee wiz
stuff that makes the process of science interesting to people.
The race to be the first data center to find the critical pre
discovery data
set is also a good media angle - SpaceWatch or one of the
coordinating
groups could award prizes etc to whoever finds the clinching data
first.
Make it a three-day media event that can be used to draw the
media in.
Most of the TV networks around the world use no more than 2-3
three main
global distribution networks and SpaceWatch could simply work
very closely
with just these main media centers (CNN, BBC, etc) to feed the
story out to
as the search for that elusive dataset continues. This way you
can be
assured that our various lazy local media networks pull down from
the
satellites the best media managed stories we can ever hope for.
This is obviously a topic for one of the next NEO conferences.
Cheers,
Simon Mansfield
Publisher
SpaceDaily.com
===============
(7) ASTEROID SCARE IN THE GERMAN MEDIA
From Christian Gritzner <christian.gritzner@mailbox.tu-dresden.de
Hi Benny,
In the "Sächsische Zeitung" (6. Nov. 2000), which is
located in Dresden
there was a small note on the 2000 SG 344 object (nearly the same
as in the
Yahoo news, which is from AP):
Los Angeles (AP) Amerikanische Wissenschaftler haben im Weltall
ein Objekt
entdeckt, dessen Flugbahn der Erde viel näher kommt als alle
bislang
vergleichbaren Gegenstände. Die Chance, dass der kleine Asteroid
oder das
Stück Weltraumschrott auf der Erde aufschlägt, liege bei 1 zu
500, erklärte Donald Yeomans von der US-Weltraumbehörde NASA in
Los Angeles.
Das Objekt sei etwa 30 bis 70 Meter lang und werde den
Berechnungen zufolge
die Erde in 30 Jahren treffen oder passieren. Sollte es sich um
einen
Asteroiden handeln, käme ein Aufschlag «einer beträchtlichen
Atomexplosion
ziemlich nahe», sagte er am Donnerstag weiter. Zunächst müsse
man sich aber
keine großen Sorgen machen.
Have you seen this one:
http://www.flatoday.com/space/explore/stories/2000b/110800e.htm
Cheers,
Christian
==============
(8) FEWER GLOBAL WARMING ITEMS ON CCNET, PLEASE
From Mike Barlow <mjb@star.ucl.ac.uk>
Dear Benny,
I've been subscribing for nearly two years now to the CCNet. I
find it full
of interesting material and am extremely grateful for the amount
of time
that you put into moderating this series, which has played an
important role
in helping to raise awareness of Near Earth Object risks.
As far as I remember (from the January 1999 survey), NEOs are the
principal
subject of the CCNet. However, in the past year an increasing
number of
items on global warming have been finding their way into the
missives. While
one can point to possible links between the effects of NEOs and
many other
phenomena, it's not clear to me why global warming items have
become so
prevalent recently. The literature on global warming is vast
compared to
that on NEO's, and so would overwhelm the NEO material if the
CCNet coverage
of global warming was to be made similarly comprehensive.
It would seem better to have a separate CCNet series devoted to
global
warming, for those who may be interested in that subject.
Otherwise the
original NEO focus of the CCNet is in danger of being lost. So,
can we have
fewer items on global warming please?
Best wishes,
Mike Barlow
MODERATOR'S NOTE: Thanks, Mike, for your suggestion. I think I
will follow
your advice and will no longer include global warming issues in
regular
CCNet issues. However, given that CCNet has, since its beginning
back in
1997, always tried to keep subscribers updated on developments in
paleo-environmental and climatological research, as well as on
the social
problems of apocalyptic science scares, I intend to post a weekly
CCNet
special on these and related issues.
Subscribers not interested in these additional can simply delete
this
additional posting without much bother. I hope that's OK with
subscribers.
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