PLEASE NOTE:
*
CCNet 110/2000 - 30 October 2000
--------------------------------
"As from 1 November countries
where a natural or technological
disaster has occurred will be able to enlist emergency
support from the
space facilities of the European Space Agency (ESA), the Centre
National
d'Etudes Spatiales (CNES, France) and the Canadian Space Agency
(CSA) by simply calling a confidential telephone number."
--
European Space Agency, 27 October 2000
(1) ASTEROID PORTFOLIO GETS A BOOST WITH NEW OPTICS
SpaceDaily, 26 October 2000
(2) SEARCH AND DESTROY
Frankfurter Allgemeine Zeitung, 26 October
2000
(3) ECHOES OF ATLANTIS
The Guardian, 25 October 2000
(4) INTERNATIONAL SPACE FACILITIES TO ASSIST DISASTER MANAGEMENT
European Space Agency <esaweb@esrin.esa.it>
(5) WHEN IS A PLANET NOT A PLANET?
Andrew Yee <ayee@nova.astro.utoronto.ca>
(6) LATE EOCENE IMPACT EJECTA
James Whitehead <jwhitehe@unb.ca>
(7) ASTEROID ARTICLE IN GERMAN NEWSPAPER (FAZ)
Phil Plait <badastro@badastronomy.com>
(8) NEW SCIENTIST FAILS TO CORRECT SENSATIONALIST SCARE STORY
Michael Paine <mpaine@tpgi.com.au>
(9) AND FINALLY: LEAKED DRAFT DOCUMENT CLAIMS GLOBAL WARMING
'WORSE THAN FEARED'
BBC Online News, 30 October 2000
=================
(1) ASTEROID PORTFOLIO GETS A BOOST WITH NEW OPTICS
From SpaceDaily, 26 October 2000
http://www.spacedaily.com/news/asteroid-00r.html
Boulder - Oct. 26, 2000
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.
CAPTION: 216
Kleopatra Rotation Movie This is a movie of the rotation of
asteroid 216
Kleopatra in Nov 1999, when radar data were also beign acquired,
that showed
the weird 'dog-bone' shape of this asteroid. These data are from
CFHT. The
asteroid rotates once every about 5 hours.
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.
Copyright 2000, SpaceDaily
================
(2) SEARCH AND DESTROY
From Frankfurter Allgemeine Zeitung, 26 October 2000
http://www.faz.com/IN/INtemplates/eFAZ/docmain.asp?rub={F1B72E2C-3783-11D4-A3AA-009027BA22E4}&doc={1104D9E7-AA5C-11D4-A3B2-009027BA22E4}
By Philip Plait
GREENBELT, Maryland. The scene is almost always the same. A lone
astronomer
(or perhaps a team of two or three), using a small telescope,
discovers a
moving object in the sky. With a swell of ominous music, the
object is
determined to be several kilometers across and headed straight
for Earth.
After some scrambling by the authorities, a team of intrepid
heroes launches
into space, plants a nuclear bomb on the rock, and gets away just
in time as
the asteroid explodes into a trillion pieces. The shattered
remnants fall
into the Earth's atmosphere, burning away into nothing more
harmful than a
spectacular fireworks show.
Does this sound familiar? It might, if you've watched any
Hollywood movies
in the past 20 years or so. The 1998 pair of movies,
"Armageddon" and "Deep
Impact," were both based on the idea that an object from
space had Earth in
its crosshairs. Both had similar plots, though very different
themes. "Deep
Impact" was a thoughtful movie, more about the emotions of
the people on
Earth as they watch the comet approach. "Armageddon"
was mostly about really
loud noises and gee-whiz special effects.
Still, the basic plotline has merit. Asteroids and comets do
exist, and
their paths do cross ours. An impact of even a small object --
perhaps 10 or
so kilometers (6.2 miles) across -- could in all practicality
wipe humans
off the face of the Earth. An impact like that, 65 million years
ago, did
just that for the dinosaurs. Smaller impacts can be just as
devastating. The
Tunguska impact had the force of about a 20 megaton bomb, yet the
rock that
caused it was only 100 to 200 meters across. A theory released
this past
month has it that the Dark Ages may have actually been caused by
a cometary
impact. Professor Mike Baillie of Queen's University in Belfast
says that
slow growth of tree rings in the year 540 indicates possible
environmental
changes, and 13th century texts hint at the near passage of a
comet in that
same year. Although this finding is highly speculative, it shows
that we
don't understand comet and asteroid impacts well, or the effects
they have
on the environment. If we don't want to suffer the same fate as
the
dinosaurs, we'd better do something about it.
FULL STORY at
http://www.faz.com/IN/INtemplates/eFAZ/docmain.asp?rub={F1B72E2C-3783-11D4-A3AA-009027BA22E4}&doc={1104D9E7-AA5C-11D4-A3B2-009027BA22E4}
=============
(3) ECHOES OF ATLANTIS
From The Guardian, 25 October 2000
http://www.guardianunlimited.co.uk
Echoes of Atlantis
The catastrophe that wiped out Helike may have inspired a legend,
reports
Iain Stewart
During the heyday of classical Greece, the city of Helike was the
renowned
cult centre for worship of Poseidon, the god of the sea and of
earthquakes.
Ironically, on a winter night in 373 BC, a violent earthquake and
seismic
sea-wave (tsunami) destroyed and submerged the city.
At the time of its destruction, Helike was capital of a con
federation of
city states on the southern shores of the Gulf of Corinth, and
was probably
located southeast of the modern city of Aigion, roughly 150
kilometres west
of Athens. Its precise location has long been the subject of
debate among
historians and archaeologists.
Ancient writers were insistent that the city lay off limits
beneath the
waters of the Corinthian gulf, but modern marine surveys had
repeatedly
failed to locate it there. Last week came the news that ruins of
ancient
Helike had been uncovered onshore, three to four metres beneath
the mud and
gravel of the Aigion coastal plain.
There was perhaps forewarning that an earthquake was about to
strike Helike,
but not of its scale. Writing in the 2nd-3rd century AD, Aelian
described
how five days before the earthquake, all the animals
had left the city en
masse, much to the puzzled amusement of the local people.
Ancient writers record that the earthquake which struck in the
night
destroyed every single building in the city and that with the
receding
waters of the tsunami, which came with the dawn, Helike was
dragged down
along with every living person, the foundations of the city lost
forever.
Until, that is, excavations this summer. The possible discovery
of Helike
was announced formally last week by Dr Dora Katsonopoulou, a
Greek
archaeologist, and Dr Steven Soter, an astrophysicist from the
American
Museum of Natural History. Their discovery was no accident. The
locations of
the excavations had been carefully targeted following 12 years of
subsurface
probing by boreholes and geophysical imaging (radar
and magnetometry) by
Soter and Katsonopoulou.
Nevertheless, the nature of the finds still took both by
surprise. In the
most important excavation, ruined walls and building foundations
were found
buried below thick deposits of black peat and lagoonal and marine
muds. The
discovery of these ruins entombed in a mixed blanket of
terrestrial,
brackish and marine sediments is certainly consistent with a
classical city
engulfed by a tsunami.
However, the excitement is tempered by the realisation that only
a few
square metres of the wide coastal plain has so far been
excavated.
For archaeologists, the prize is that, given the nature of
Helike's demise,
the resurrected city may provide an unplundered, unmodified
"time capsule"
from the classical era. Its shallow onshore location may allow
the greater
part of the city to be excavated, giving Greece its very own
Pompeii.
For earthquake geologists, Helike offers a different prize. For
us, the city
is fossilised result of a scale of seismic event that we know can
strike the
earthquake-prone shores of the Aegean region but for which we
have no modern
analogue.
Killer earthquakes struck the Aigion shores in 1861 and 1995, but
while they
caused widespread coastal submergence and some loss of life,
neither of them
were of the enormity of the 373 BC event.
So how often do such catastrophic sea-quakes occur in this
region?
In the early 1990s, I first went to the Helike area with that
question in
mind. As part of a Royal-Society-funded honeymoon I studied the
earthquake
fault that ruptured in 1861, and from raised shorelines along the
Helike
coast I suggested that the same fault probably moved violently
around the
time of the 373 BC event.
In 1995, I turned my attention 100 kilometres northwards to
another
earthquake-prone coast - the Gulf of Atalanti. Here, with two
research
students (Vik Buck and Thomas Dewez), and in collaboration with
Stella
Kortekaas (Coventry University) and Andy Cundy (now at the
University of
Sussex), we investigated the effects of coastal
flooding triggered by a
damaging earthquake and tsunami in 1894.
We were able to detect signs of this seismic disturbance in the
modern marsh
sediments, so Soter and Katsonopoulou were interested in whether
we could
detect the older but much larger Helike inundation event.
This summer, funded by Brunel University and an EU project
investigating
long-term seismic hazard in the Gulf of Corinth, I returned to
Helike. I was
joined by Thomas, Andy and a new Brunel colleague Suzanne Leroy,
professor
in palaeoenvironmental reconstruction. Working alongside Soter
and
Katsonopoulou, our task was to drill shallow boreholes in a
suspected former
lake bed. For the archaeologists, the lake was potentially the
sacred grove
of Poseidon for which ancient Helike was famed.
For us, the site lay a few tens of metres from the Helike fault,
which we
suspected had ruptured during the 373 BC earthquake, and
therefore the lake
may preserve an archive of that past earthquake activity.
However, the
freshly recovered sediment cores have yet to reveal their
story.
Undoubtedly the most popular aspect of the Helike discovery will
be its
association with the Atlantis legend. The story of Atlantis is
first
recorded by the Athenian philosopher Plato, writing in the
mid-fourth
century BC.
Plato would have been in his early 50s when the 373 BC earthquake
obliterated the thriving city of Helike, and the tragedy would
have been
reminiscent of a similar catastrophic event that struck mainland
Greece
around the time of his birth.
In 426 BC, a major earthquake caused widespread seismic
destruction and
tsunami inundation around the Gulf of Evvia, including, in the
Gulf of
Atalanti, the reported separation of Atalanti Island from the
mainland.
In his "dialogue" Timaeus, Plato recounts how
"there occurred violent
earthquakes and floods" and then, in one awful day and night
"the island of
Atlantis _disappeared in the depths of the sea." The
parallels between
Plato's Atlantis and the 373 BC and 426 BC earthquakes are
enticing,
particularly given that even after two and a half millenia of
notable
historical seismicity in Greece, these two earthquakes stand out
as
particularly catastrophic events. Perhaps the Atlantis legend is
the real
legacy of Helike.
Iain Stewart is a senior lecturer in geography and earth sciences
at Brunel
University. His research is in earthquake geology, and he has
recently
co-edited books on The Archaeology Of Geological Catastrophes and
Coastal
Tectonics.
Copyright Guardian Newspapers Limited
==============
(4) INTERNATIONAL SPACE FACILITIES TO ASSIST DISASTER MANAGEMENT
From European Space Agency <esaweb@esrin.esa.it>
A SINGLE TELEPHONE LINE TO MOBILISIE SPACE FACILITIES FOR NATURAL
DISASTER
MANAGEMENT
As from 1 November countries where a natural or technological
disaster has
occurred will be able to enlist emergency support from the space
facilities
of the European Space Agency (ESA), the Centre National d'Etudes
Spatiales
(CNES, France) and the Canadian Space Agency (CSA) by simply
calling a
confidential telephone number.
The number will be notified to authorised users. As soon as a
natural
disaster occurs, they will be able to call an operator at ESRIN
(the ESA
establishment in Frascati, Italy), who will immediately contact
the duty
engineer at ESA, CNES or the CSA.
The engineer will then deploy various space facilities of the
three agencies
to assist the country where the disaster has struck: earth
observation data
from SPOT, Radarsat, ERS and soon Envisat, facilities for
telemedicine and
navigation (e.g. to track drifting buoys marking an oil slick),
ground
infrastructures and archive pictures. Once launched, the Artemis
and Stentor
communication satellites will also be available to relay data to
the country
concerned.
Whenever called upon in a crisis, the three agencies will
designate a
project manager to liaise with the country affected. Assistance
will not be
confined to supplying satellite data, but will include processing
and
interpretation as well.
The decision to set up this 24-hour hotline was taken on 25
October, at the
second meeting of the Board of the International Charter on Space
and Major
and Disasters. The Charter was signed on 20 June this year by ESA
and CNES,
with the CSA subscribing on 20 October. It is a far-reaching
initiative to
promote cooperation by space system operators in the event of
natural or
technological disasters. The Charter is open for signature by
satellite
operators anywhere in the world. All partners undertake to
cooperate on a
voluntary basis, with no exchange of funds between them.
For further information, please contact:
ESA press service: Franco Bonacina, tel: +00.331.53.69.71.55, fax
+00.331.53.69.76.90
CNES press service: Julien Guillaume, tel: +00.331.44.76.76.87,
fax
+00.331.44.76.78.16
CSA press service: Anna Kapiniari, tel: +1.450.926.4350 - fax
+1.450.926.4352
=============
(5) WHEN IS A PLANET NOT A PLANET?
From Andrew Yee <ayee@nova.astro.utoronto.ca>
Office of News & Information
University of Pittsburgh
Pittsburgh, Pennsylvania
Contact:
John Fedele, fedele@univ-relations.pitt.edu,
412-624-4148
10/26/2000
When is a planet not a planet? Researchers see stars instead
PASADENA -- More than half of the recently detected extrasolar
planets
appear not to be planetary objects at all, according to a
preliminary
astrometric study conducted by researchers at the University of
Pittsburgh's
Allegheny Observatory, the Lunar and Planetary Institute, and the
Korea
Astronomy Observatory. The study is being presented at the
Division for
Planetary Sciences of the American Astronomical Society
meeting, October
23-27, in Pasadena, California.
The study suggests that the companions are not planets, but brown
dwarfs
(objects more massive than planets but smaller than stars),
double stars, or
low-mass stars. The confusion arises because of the inability of
the radial
velocity techniques, the basis of the original announcements, to
determine
the masses of the companions. Radial velocity observations
cannot distinguish between a planet in an orbit that is viewed
nearly edge
on from a brown dwarf or stellar companion in an orbit that is
nearly in the
plane of the sky.
George Gatewood of the University of Pittsburgh's Allegheny
Observatory,
Inwoo Han of the Korea Astronomy Observatory, and David C. Black
of the
Lunar and Planetary Institute used astrometric data from the
European Space
Agency (ESA) Hipparcos spacecraft, as well as radial velocity
data,
to determine the inclination of the companion orbital planes to
the
line-of-sight of the observer and thus to determine masses for
the proposed
extrasolar companions.
"A striking result is the finding that orbital inclinations
of the systems
studied are extremely low -- that is, the orbital planes of these
companions
appear to be oriented nearly face on to the observer," said
Black. "This
contradicts the assumption that the line-of-sight angle is
random in the radial velocity studies. It suggests that radial
velocity
studies that have reported detection of low-mass companions may
be biased
toward small inclinations in their selection of target
systems."
"Part of the problem arises because masses smaller than that
of Jupiter are
very difficult to detect, thus most of the objects that have been
detected
and are suspected to be planets have masses greater than that of
Jupiter,
the most massive planet in our solar system," said Gatewood.
"Until very recently, there were few known objects between
one Jupiter in
mass and 80 times as much, and those are small stars."
Now that some objects in this mass range have actually been
discovered,
astronomers are as confused as everyone else about what to call
them,
Gatewood said. "The answer has to do with how they form, but
that is
difficult to determine. Unfortunately, some astronomers have
started
calling objects less than 10 Jupiters in mass 'planets', a sort
of mystical
dividing line. To be scientifically correct, we should just call
these
objects 'substellar.' "
In reducing the data to determine the companion orbits, the
authors arrived
at four groupings of objects ordered by increasing value of the
ratio of the
estimated orbit's semi-major axis to its standard error.
Nine stars are estimated to have companions with true masses of
10-15
Jupiters or less. This is slightly higher than the minimum masses
given by
the radial velocity studies for these stars, but not excessively
so.
A second group of 11 stars appear to have companions in the range
of 15-80
Jupiters, masses substantially higher than the radial velocity
results,
which are thus likely to be brown dwarfs rather than planets.
A third group of four stars yields companion masses that are
clearly
stellar, probably M dwarf stars, although statistical artifacts
have not
been completely ruled out.
A final group of six will require additional astrometric
observations before
companion masses and inclinations can be determined with
certainty.
An independent study by Mayor and colleagues (Halbwachs et al.
2000, also
using Hipparcos data) of systems discovered by radial velocity
searches with
minimum masses in the brown dwarf range, shows a similar strong
tendency (7
of 11 objects) toward systems with very low inclination
angles.
This result obtained from combining astrometric data with the
radial
velocity findings is consistent with earlier studies that have
noted that
the orbital periods and eccentricities of so-called
"extrasolar planets" are
distributed in a way that is statistically indistinguishable from
binary
stars. This suggests that many, perhaps most, of the systems that
have been
identified as having planetary companions are indeed stellar or
brown dwarf
binaries.
Han, Black, and Gatewood stress that this is a preliminary
result. Its
intent is to guide future observers in their attempt to provide
better data
for the study of the origins of our own planetary system. Their
decision to
publish the initial results is based upon the surprising trend
discovered by
the study, not by the result for any individual system. They have
already
begun follow up studies with astrometric telescopic equipment at
the
University of Pittsburgh's Allegheny Observatory.
============================
* LETTERS TO THE MODERATOR *
============================
(6) LATE EOCENE IMPACT EJECTA
From James Whitehead <jwhitehe@unb.ca>
Dear Benny,
Apparently the link to the EPSL paper I referred to in a recent
CCNet
posting re: determining the provenance of minute quantities of
upper Eocene
impact ejecta using isotopes, will not work for most of your
readers who do
not subscribe to the Elsevier journals through the University of
Toronto. My
apologies.
Interested viewers can read the article from my homepage instead,
at:
http://www.unb.ca/web/geology/pdf.htm
Whitehead, J., Papanastassiou, D.A., Spray, J.G., Grieve, R.A.F.
and
Wasserburg, G.J. 2000. Late Eocene impact ejecta: geochemical and
isotopic
connections with the Popigai impact structure, Earth and
Planetary Science
Letters 181, p.473-487.
---------------------------------------------
Dr. James Whitehead
Impact Geology Group
Planetary and Space Science Centre
Department of Geology
University of New Brunswick
=====================
(7) ASTEROID ARTICLE IN GERMAN NEWSPAPER (FAZ)
From Phil Plait <badastro@badastronomy.com>
Hi Benny--
I wanted to give you a head's-up: I have a semi-weekly astronomy
column that
has just started in the German newspaper Die Frankfurter
Allgemeine Zeitung.
The column will focus on the impact of astronomy on culture. The
first two
articles I wrote are about searching for asteroids and what to do
if we find
one headed our way. The first article was published on the
25th, and a link
to the English version of the column can be found through my own
website at
http://www.badastronomy.com/zeitung/index.html.
The second part will be out
November 9 or so.
Note that an editing error in the 8th paragraph changed my intent
somewhat;
I said originally that we know of 100 or NEAs which is only a
fraction of
the total out there, but this was changed to imply that there are
only 100
and we have seen a fraction of *those*. To a layman this may not
make much
difference, but of course it's inaccurate. The mistake has been
noted and
the staff there will fix it soon. The link to my site at
the bottom of the
article has a typo as well. The link I give above is correct.
Note that I did *not* write the
bio of me! ;-)
I wrote a third article about asteroids discussing the role of
scientists
and journalists when we a PHO is found. The column will not
usually be about
asteroids (a fourth is about black holes, and I have others
planned about
extrasolar planets, nomenclature in astronomy, etc), but this
seemed like a
good topic with which to start.
I will link to the articles from my Zeitung webpage as they go
live.
Thanks,
Phil Plait
* * *
* * The Bad
Astronomer *
* * *
==================
(8) NEW SCIENTIST FAILS TO CORRECT SENSATIONALIST SCARE STORY
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
The cover story for the 7 October issue of New Scientist was
called 'The
Drowning Wave'. It claimed the US east coast was under threat
from a huge
tsunami generated by an undersea landslide that might occur in
the Canary
Islands. I noted concerns about these claims in a CCNet posting
on 6 October - two scientists approached by BBC had expressed
doubts about
the tsunami range estimates. I also wrote to the editor of New
Scientist on
6 October pointing out those concerns. I had hoped it would be
published
prior to the airing of the sensational(ised) Horizon program. I
am
disappointed that New Scientist has not published my letter. You
might wish
to publish it on CCNet.
regards
Michael Paine
The Editor, New Scientist
Sorry to spoil a sensational story but... The feature article
'The Drowning
Wave' greatly exaggerates the threat to the U.S. East Coast from
a tsunami
generated near the Canary Islands. In July last year the Tsunami
Society
held a conference on the subject of
"mega-tsunami" (conference proceedings
are available from http://epubs.lanl.gov/tsunami/
, including my paper on
tsunami from asteroid impacts). Although there is much work to be
done on
modeling these giant waves it is evident that many of the
predictions from
the 1980s and early 90s overstated the long-range damage
potential of
tsunami. Firstly many studies used an unusually high
amplification
factor for calculating the height of the wave as it moved from
deep to
shallow water. Factors of 40 have been quoted but these only
occur in very
unusual locations such as parts of Hawaii and Japan. A more
typical factor
is three. In other words, the run-up height of the tsunami onto
the shore is usually no more than about 3 times the height of the
wave in
deep water. The second issue is the rate of dissipation of the
tsunami over
the first few hundred kilometres. Multiple complex waves are
usually
generated by the mega-tsunami event (such as an asteroid
striking the ocean or a large undersea landslide) and these tend
to travel
at different speeds so the wave energy becomes dissipated. I have
been in
touch with Charles Mader, a tsunami expert from Hawaii and
Hermann Fritz,
who did some of the brilliant modeling work for the potential
volcano
collapse mentioned in your article. They are both concerned that
the
modeling only covered the initial wave characteristics - the
first few
minutes. Fritz told the BBC that the
waves would decrease and transform massively as they moved into
the deep
water of the Atlantic. He said he did not make any statements
regarding the
transoceanic wave characteristics. Mader confirmed the doubts
about large
waves crossing the Atlantic -- he told Horizon that a La Palama
landslide would not be a threat to the U.S. -- but it appears
that the BBC
ignored the advice of both scientists. The latest research
suggests that it
would require an asteroid at least a kilometre in diameter to
generate
tsunami that would be highly destructive across an entire ocean.
An impact
that size would, of course, give the human race other problems
beside
tsunami to think about. For smaller asteroids, and undersea
landslides, the
waves become small by the time they cross an ocean and they only
pose a
threat to highly vulnerable locations such as parts of Hawaii.
The situation
is quite different for shorelines close to the event, such as
occurred in
New Guinea in 1998. Here the waves did not have time to dissipate
and water
reached more than 10 metres in height as it swept through the
coastal
villages. There are concerns about tsunami generated by undersea
landslides
off the U.S. continental shelf (for example see
http://www.nsf.gov/od/lpa/news/press/00/pr0038.htm
) and I have concerns
about a similar threat to Sydney's coastline, but destructive
tsunami from
the other side of the ocean are highly unlikely.
Michael Paine
My research on "mega-tsunami" is described at
http://www1.tpgi.com.au/users/tps-seti/spacegd7.html
===============
(9) AND FINALLY: LEAKED DRAFT DOCUMENT CLAIMS GLOBAL WARMING
'WORSE THAN
FEARED'
From the BBC Online News, 30 October 2000
http://news.bbc.co.uk/hi/english/sci/tech/newsid_996000/996115.stm
By environment correspondent Alex Kirby
A draft report prepared for the world's governments says that the
Earth may
heat up much more than current forecasts suggest.
The report, by scientists from the Intergovernmental Panel on
Climate Change
(IPCC), says average global temperatures could rise twice as much
as they
thought earlier.
It foresees a possible rise of 6C above 1990 levels. Five years
ago, the
IPCC was predicting a probable maximum increase of 3C.
Scientists believe the level of carbon dioxide emissions being
forecast in
the report could trigger the mass death of forests and
significant rises in
sea levels, as well as crop failures and extreme weather.
Fossil fuels
The report is only a draft, and it is liable to be altered before
publication next May.
But it is bound to loom large at next month's meeting in the
Netherlands of
the countries which have signed the Kyoto Protocol, the
international
agreement on tackling climate change.
That commits signatories to collective cuts in greenhouse gas
emissions of
5.2% below their 1990 levels by some time between 2008 and 2012.
Many scientists say Kyoto is only a modest start, and that cuts
in emissions
of the main greenhouse gas, carbon dioxide (CO2), will have to
reach 60% or
more in the next half-century to keep climate change within
tolerable
bounds.
Climate science
The draft IPCC report concludes that the burning of fossil fuels
and other
forms of pollution caused by human activities have
"contributed
substantially to the observed warming over the last 50
years".
FULL STORY at
http://news.bbc.co.uk/hi/english/sci/tech/newsid_996000/996115.stm
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