PLEASE NOTE:


*

CCNet 33/2002 - 11 March 2002
-----------------------------


"Amid the was it or wasn't it debate about the U.S. recession, a
senior Federal Reserve official has coined a new phrase for the economic
downturn that began last March, dubbing it: "the Pluto recession."
Speaking to a group of reporters on Friday, St. Louis Fed President
William Poole likened the controversy over how to describe the U.S.
economy's recent woes to the wrangles among astronomers about the
planet Pluto. "The astronomers argue about whether Pluto is or is not a
planet. It's a marginal object. Some astronomers say Pluto is a
planet and other astronomers say Pluto is not a planet...Any time you have
an event that is out on the borderline, by definition it's not so clear."
--Caren Bohan, Reuters


(1) US REMEMBERS 11 SEPTEMBER
BBC News Online, 11 March 2002

(2) THE DISCOVEY OF 2002 EA
Mark Kidger < mrk@ll.iac.es >

(3) THE DISCOVERY OF 2002 EA: THE FIRST SPANISH NEA DISCOVERY
Rafael Ferrando1 < Rferrand@terra.es >

(4) COMET IKEYA-ZHANG
Mark Bailey < meb@arm.ac.uk >

(5) COMET IKEYA-ZHANG CONTINUES TO BRIGHTEN
Sky & Telescope, 6 March 2002

(6) VIEWER'S GUIDE TO NEW COMET IKEYA-ZHANG
Space.com, 8 March 2002

(7) COMET IKEYA-ZHANG PHOTO GALLERY
Spaceweather.com

(8) EARTH SET FOR BRUSH WITH COMET
The Guardian, 11 March 2002

(9) EARTH TO ASH IN A FLASH
Sunday Herald Sun, 10 March 2002

(10) CHANCES OF DYING FROM AN IMPACT
Michael Paine < mpaine@tpgi.com.au >

(11) UNDERESTIMATING THE IMPACT HAZARD FROM SMALLER NEOs?
Jens Kieffer-Olsen < dstdba@post4.tele.dk >

(12) AND FINALLY: FED OFFICIAL DUBS US SLUMP THE "PLUTO RECESSION"
Reuters, 8 March 2002


============
(1) US REMEMBERS 11 SEPTEMBER

>From the BBC News Online, 11 March 2002
http://news.bbc.co.uk/hi/english/world/americas/newsid_1865000/1865988.stm

Three thousand people died in the attacks

The United States is preparing to mark six months since the 11 September
terror attacks with a series of events in New York and Washington.

In New York, firefighters, survivors and relatives of victims of the attacks
will gather at the remains of the World Trade Center as two memorials are
unveiled in remembrance of those who died.

The attacks shocked the world

In Washington, President George W Bush will lead ceremonies at the White
House, attended by foreign ambassadors and more than 1,000 guests.

Mr Bush will also deliver a speech, outlining the future shape of the US-led
war on terror.

The commemoration will get under way with a moment of silence in New York at
0846 local time (1346 GMT) - the exact time hijacked American Airlines
Flight 11 was deliberately crashed into the north tower of the trade centre.


A second silence will be held 17 minutes later, in memory of the moment
United Airlines Flight 175 ploughed into the south tower.

Bell ringing

About 3,000 people lost their lives when the twin towers collapsed. Many
more died in a similar attack on the Pentagon in Washington and in a further
hijacked airliner that crashed in rural Pennsylvania.

Despite the destruction, one structure - a 45,000lb (2,041 kg) sculpture
called The Sphere - survived and will be dedicated to the victims.

Mayor Giuliani will speak at the ceremony

The steel and bronze design, which had stood in the centre of the World
Trade Center plaza, will become part of a temporary memorial near the
remains of the building.

New York Mayor Michael Bloomberg, his predecessor Rudolph Giuliani, who led
the city through its darkest hour, and New York state Governor George Pataki
will lead the commemorations in the park, attended by families of the
victims.

The ceremony will close with the ringing of the bell from the New York Fire
Department, which lost 343 members who went to rescue people trapped in the
twin towers.

One of the main events will take place at dusk, when 12-year-old Valerie
Webb, who lost her father in the attack, will switch on two powerful beams
of light symbolising the twin towers.

The Tribute of Light will project two 50 foot (15 metre) squares of light
one mile (1.6 kilometres) skyward and be visible for a radius of about 20
miles (32km).

The memorials will remain until a final decision is made on a permanent
tribute to the victims.

'Rogue' states

At the White House, President Bush will reflect on the past six months and
the fight against terror in an address to victims' relatives, members of
Congress and other administration officials.

Bush will talk about the fight against terror

White House spokesman Gordon Johndroe said Mr Bush would offer "a broad
outline of what's been accomplished and where we are headed, the challenges
we face as the war on terrorism continues".

He said the president would also focus on the importance of the global
coalition against terror.

Mr Bush is also expected to highlight the danger of "rogue" nations which
are working to develop weapons of mass destruction.

At the Pentagon, US Defence Secretary Donald Rumsfeld will meet military
leaders from the coalition and tour reconstruction works six months after
the building came under attack.

US Vice President Dick Cheney, who is en route to the Middle East to shore
up support for America's campaign against international terrorism, will mark
the day of remembrance with UK Prime Minister Tony Blair in London.

Copyright 2002, BBC

=============
(2) THE DISCOVEY OF 2002 EA

>From Mark Kidger < mrk@ll.iac.es >

Dear Benny:

Attached is Rafael Ferrando's discovery notes for 2002 EA. Reading it, I
think that people will agree that it is a splendid demonstration of just how
well the system handles such discoveries and how astonishingly fast
everything worked even on a Saturday night.

Another point though is that raised by your correspondent on March 6th.
Despite the fact that there are astonishingly efficient programmes such as
LINEAR, NEAT and LONEOS in the northern hemisphere, some objects of
significant size still slip through the net. In this case the object has
been discovered only two weeks before a (fairly) close encounter - although
it is 20 times the distance of the Moon.

As readers will see, this was a pure chance discovery: the object just
happened to be there passing close to another asteroid that the astronomer
wanted to observe and Rafael Ferrando just happens to be one of the few
people who would both recognise a very faint trail (even when it is pointed
out on the discovery images I can barely see it on my terminal), realise
that it was a NEO in need of further observation, and be capable of getting
all the necessary results reduced on-line. This suggests that there may well
be other asteroids that slip through because they aren't recognised - maybe
one of your correspondents from the NEO community would like to comment on
the implications for discovery statistics.

Mark Kidger

=========
(3) THE DISCOVERY OF 2002 EA: THE FIRST SPANISH NEA DISCOVERY

Rafael Ferrando1 < Rferrand@terra.es >

Observatorio Pla D'Arguines
(IAU Site Code 941)
Castellón, Spain

On March 2nd 2002, as usual on observing nights I prepared to take exposures
of various comets, supernovae and asteroids with my 12-inch (30cm) LX-200
telescope and ST9-E CCD. After taking some images of various comets (P/2001
TU80 (LINEAR-NEAT), C/2002 C2 (LINEAR), and C/2001 C1 (Ikeya-Zhang) and the
supernova Sn 2002ap, I started to take recovery measurements of asteroids
that have just a few days of observing arc in their first opposition. This
work is very important because many of these asteroids would be lost if they
could not be recovered in their second opposition and thus their orbit would
not be well determined.

The first field that I observed was of 2000 QW65, a main belt object
observed over an arc of 2 months in 2000. This field also included two
numbered asteroids: the rather poorly observed 1912 (Annubis) and the
unnamed asteroid 5480 (1989 YK8).

In this field I noticed a faint trail. Although this might just have been
noise in the CCD, there was also the chance that it could be a NEO, so I
took another exposure. When this second exposure appeared I blinked the two
to see if the mystery object reappeared and if it moved between them. On
doing this it appeared possible that it could be a NEO, so I took two more
exposures.

While exposing, I checked the Minor Planet Center (MPC) computer and
discovered that there is no known NEO in this position. On finding this, my
heart leapt into my mouth and my pulse raced. Conscious of the potential
importance of the discovery I took astrometry of the exposures and sent it
to the MPC. Within seconds the MPC answers asking me to follow this object
as long as possible as it appears to be a NEO.

The NEO confirmation page at the MPC automatically generated an announcement
with the positions that I had supplied, requesting other observatories to
confirm it. At the same time, I contacted my colleague, Pepe Manteca at
Begues (IAU Site Code 170), and we sent an urgent notification to the
Spanish language comet observers mailing list called "Cometas_Obs"
(Cometas_Obs@yahoogroups.com) in the hope that another Spanish observatory
could confirm it, although bad weather in much of Spain made this seem
unlikely.

I was able to follow the object from my observatory for almost 5 hours,
although fog and cloud started to appear and made the object difficult to
observe. As each exposure came off the CCD it was measured and sent to the
MPC.

The first exposure that showed the object was taken at 21:46UT and the MPC
was alerted just after 21:51UT. When I had stopped observing - the last
usable exposure came down from the CCD at 01:12UT - and had sent off the
last set of measures I could check the NEO Confirmation Page and saw that
Ondrejov Observatory in the Czech Republic had reported four measurements
starting at 00:32UT, less than 3 hours after my initial report. The object
was confirmed. This allowed me to sleep easier because I was in need of a
few hours rest!

I went to be hoping that the weather would improve and that, on the Sunday
night I could recover it. However, luck was not with me - it was cloudy and
I could not observe. That night though observers from all round the world
could observe, amongst them the Observatorio Astronómico de Mallorca (OAM),
on the Mediterranean island of Majorca, quite close to my own observatory
and one of the teams alerted by the mailing the previous night.

With two nights of observations, a provisional orbit could be calculated and
a designation (2002 EA) assigned. 2002 EA was found to be an Apollo
asteroid, one that crosses the Earth's orbit and thus one of the potentially
most dangerous class of NEAs. Given a 15% albedo it would be about 130
meters across and will pass just behind the Earth in its orbit at about 8.5
million kilometers distance on March 15th.

1 Aclaratory Note: This text is basically a translation of Rafael Ferrando's
comments on the discovery. However, I have received full authorisation from
him to make such changes as seen necessary. These have mostly involved
adding additional background and details to make the text more readable
(Mark Kidger).

================
(4) COMET IKEYA-ZHANG

>From Mark Bailey < meb@arm.ac.uk >

Dear Benny,

Readers of CCNet might be interested to know that we have put a short
information sheet on the new comet C/2002 C1 (Ikeya-Zhang) on the Armagh
Observatory web-site ( http://star.arm.ac.uk/ikeya-zhang ). It is now an easy
object with binoculars (at least for those with a good western horizon),
about magnitude 5.0 when I observed it on Saturday evening. In
other words brightening roughly according to predictions.

Best wishes,

Mark

==============
(5) COMET IKEYA-ZHANG CONTINUES TO BRIGHTEN

>From Sky & Telescope, 6 March 2002
http://skyandtelescope.com/observing/objects/comets/article_477_1.asp

By John E. Bortle

The comet discovered on February 1st by Kaoru Ikeya and Daqing Zhang not
only seems to have a bright future but possibly a most interesting past.
Just two days after the comet was first spotted, a similarity was noticed
between Comet Ikeya-Zhang's preliminary orbital elements and those of a pair
of much earlier objects (C/1532 R1 and C/1661 C1). Finally, on February
25th, with 309 astrometric observations in hand, Brian G. Marsden
(Smithsonian Astrophysical Observatory) concluded that this is, in fact, a
likely return of the comet of 1661.

Ikeya-Zhang's photometric behavior was a topic of much conversation among
comet observers during mid-February. C/2002 C1 is brightening rather more
rapidly than expected. The comet's coma appears small, bright, and tightly
condensed, while the comet itself exhibits a very high gas to dust ratio.
Such "gas" comets typically brighten more quickly with their approach to the
Sun than do those with a large dust component.

Because of this, C/2002 C1 could put on a much better show than most expect;
a peak of magnitude 3.0 would not be at all surprising. The comet could
potentially unfurl an ion tail 10° to 15° in length as it sweeps by Earth.
However, the decidedly bluish color of this tail will make it far more
prominent to the camera than to the eye.

Keep in mind that Comet Ikeya-Zhang will be difficult to locate low in the
western evening sky after sunset in mid-March. Nevertheless, the comet is
now visible to the naked eye. Michael Begbie of Zimbabwe writes that he and
other observers in Poland and Italy spied the comet without optical aid on
the evening of February 28th. I saw the comet on March 1st (UT) in 10 x 50
binoculars and, at magnitude 5.5, its brightness was consistent with
previous observations made over the preceding week. I still believe the
comet will brighten beyond current predictions.

During the first week of April, the comet skirts north of the Sun and enters
the morning sky. Skywatchers in the Northern Hemisphere will likely get
their best views in late April, when the comet makes a slow trek from
Cassiopeia into Cepheus and then Draco.

The comet reaches its closest point to the Sun (perihelion) on March 18th.
At that time it will be midway between the orbits of Venus and Mercury, at
0.51 astronomical unit (76 million kilometers) from the Sun.

The object's dual name recognizes the two comet hunters who first found it
on February 1st: Kaoru Ikeya of Shizuoka prefecture, Japan, and Daqing Zhang
in Henan province, China. Zhang described the comet as a small,
8.5-magnitude glow 3 arcminutes across in his 20-cm (8-inch) reflector.

If the name "Ikeya" rings a bell, it should. Between 1963 and 1967, Kaoru
Ikeya discovered or codiscovered five comets. One of them, Comet Ikeya-Seki,
was the famous naked-eye Sungrazer of 1965. But little had been heard from
Ikeya (at least outside Japan) until he made his sixth comet discovery last
week. "He is the phoenix!" says astrophotographer Shigemi Numazawa of
Niigata, who adds that Ikeya, now age 58, manages the Ikeya Optical Lab, a
supplier of telescope mirrors to Japan's discriminating observers.

- - - - - - -
John Bortle is a well-known comet expert and an authority on comet observing
throughout history. His Web article "The Bright Comet Chronicles" provides
brief accounts of all those comets seen between 1800 and 1997 which attained
an observed maximum brightness of +2 or greater.

Copyright 2002 Sky Publishing Corp.

==============
(6) VIEWER'S GUIDE TO NEW COMET IKEYA-ZHANG

>From Space.com, 8 March 2002
http://www.space.com/spacewatch/spacewatch_comet_020309.html

By Joe Rao

A big question for skywatchers during the next couple of months is how
bright the newly discovered comet, Ikeya-Zhang, will become. The answer
can't be accurately predicted, but this much is nearly certain: The comet
will provide an opportunity that comes along just once or twice per decade.

Comet Ikeya-Zhang will make its closest approach to the Sun on March 18,
when it will be roughly 47 million miles away or midway between the orbits
of Mercury and Venus. Shortly after it was discovered on Feb. 1, it appeared
there was a chance that Ikeya-Zhang might evolve into the comet of the
decade, judging by an initial rapid brightening and its possible link to a
spectacular 16th Century comet.

Observations of the comet in recent days however, have tempered those
initial high expectations.

Currently, Ikeya-Zhang appears in binoculars and small telescopes with a
faint and somewhat distorted bluish gas tail about 5 degrees long
accompanying a sharp, well-condensed head of about fifth magnitude.

Dimly visible

Ikeya-Zhang might eventually get as bright as third magnitude, meaning that
it should be at least dimly visible to the naked eye in dark skies, though
better seen in binoculars or telescopes. That kind of brightness would still
make Ikeya-Zhang a very fine comet from the viewpoint of an amateur
astronomer, especially in April, when it will be approaching the Earth and
become well placed high in a dark sky.

But at the time of this article's publication, it doesn't appear that this
comet will become the kind of spectacle that comet Hale-Bopp was in grabbing
the public's attention in 1997.

However, regardless of what script we write here for Ikeya-Zhang's
performance, be advised that comets are notoriously bad actors. Few
celestial events have greater false-alarm potential than the interplanetary
vagabonds we call comets.

Earlier this winter, for example, comet LINEAR WM1 briefly and unexpectedly
flared-up, becoming as bright as third magnitude, though visible only from
the Southern Hemisphere. Comet Ikeya-Zhang could brighten similarly and
provide a real surprise.

Ancient visitor returns

Soon after a preliminary orbit was calculated for Ikeya-Zhang, some orbital
experts, lead by Syuichi Nakano of Japan, noticed a similarity to a pair of
much earlier comets that appeared in 1532 and 1661.

The 1532 comet, in particular, was a strikingly bright comet, according to
Oriental records. Curiously, during the first week or two that Ikeya-Zhang
was under careful scrutiny by observers worldwide it appeared to be
brightening at an unusually rapid pace. Perhaps, some thought, this was
going to be the return of the great comet of 1532.

Excitement began to build with the prospects of a potentially spectacular
comet gracing the late winter and early spring skies.

But then, during late February, Ikeya-Zhang's brightening noticeably slowed.

A more recent orbital computation by Brian Marsden of the Smithsonian
Astrophysical Observatory in Cambridge, Massachusetts, now suggests
Ikeya-Zhang may be a return of the 1661 comet, not the one from 1532. This
is a come-down of sorts for skywatchers, since historical records suggest
the 1661 was a middle-of-the-road performer.

Interestingly, this is not the first time that these same two comets were
embroiled in an identity crisis. In the late 17th Century, Sir Edmond Halley
-- the same man for whom the most famous comet is named -- compared the
apparent similarities of the orbits of the comets of 1532 and 1661 as part
of his own comet studies. He became convinced that they were one in the
same, even implying that there would be a return of the comet in 1790.

What Ikeya-Zhang might look like

Joannes Hevelius of Gdansk, Poland, observed and wrote extensively about the
1661 comet in his 1668 tome, "Cometographia." He went on to report that the
nucleus, or head, of the 1661 comet displayed "multiple structure," as seen
in his crude telescope. Rather than seeing the break-up of the comet
nucleus, which can cause a comet to brighten suddenly, Hevelius might have
been observing a series of bright jets of material being expelled from the
comet head.

The 1661 comet also displayed a tail that measured 6 degrees in length (for
comparison, 10 degrees is roughly equal to the width of your fist held at
arm's length).

These descriptions may help to provide clues as to how comet Ikeya-Zhang may
appear to us in the coming weeks. One important difference, however, is that
the 1661 comet headed directly away from the Earth after sweeping closest to
the Sun (a point called "perihelion") and quickly faded away. But
Ikeya-Zhang will be approaching the Earth for a number of weeks following
its perihelion and thus should remain visible for a much longer stretch of
time.

If the 1661 comet and Ikeya-Zhang are indeed the same, it would set a record
of sorts: the longest amount of time that has elapsed between the discovery
of a comet and a definitive sighting upon its return to the inner solar
system.

The current record is held by comet Herschel-Rigollet, discovered by
Caroline Herschel in 1788 and rediscovered 151 years later by Roger
Rigollet, in 1939. Comets with orbital periods of 200 years or less are
considered "short period" comets. If Ikeya Zhang is the 1661 comet, this
would be the very first time that the return of a "long period" comet, with
an orbital period greater than 200 years, has ever been observed and noted
as such.

The 1661 comet might have reached the far end of its cigar-shaped elliptical
orbit around the year 1830, when it was probably more than 9 billion miles
from the Sun -- more than twice as far away as Pluto. If so, then ever since
it has been on a slow, steady course taking it back toward the Sun, finally
to reach its closest point again on March 18.

Copyright 2002, Space.com

=============
(7) COMET IKEYA-ZHANG PHOTO GALLERY

Spaceweather.com
http://www.spaceweather.com/comets/gallery_iz.html

=========
(8) EARTH SET FOR BRUSH WITH COMET

>From The Guardian, 11 March 2002
http://www.guardian.co.uk/uk_news/story/0,3604,665361,00.html

A comet discovered by astronomers this year and heading past the Earth will
be bright enough to see with the naked eye later this month.

Comet Ikeya-Zhang, named after the Japanese and Chinese astronomers who
first spotted it on February 1, will be the brightest comet to make an
appearance since Hale-Bopp in 1997.

During the second half of this month and the first half of April it will
brighten rapidly to a point where, under good conditions, it should be
visible to the naked eye as a faint smudge in the western sky.

Town dwellers will have a harder job seeing it than people in the
countryside, but a low-powered pair of binoculars should provide a much
clearer view.

Robin Scagell, from the Society for Popular Astronomy, said the comet, which
looks like a slightly hazy star with a bright tail, was already visible. "I
was looking at it last night. It's not amazingly bright at the moment. Some
people have seen it with the naked eye. But it should get brighter over the
next few weeks.

"The comet has a pronounced tail extending over five to 10 degrees, which is
about 10 times as long as the width of the moon."

Ikeya-Zhang is a periodic comet, which means it returns to the inner solar
system on a regular basis.

It would have been visible in 1661 and may also have been seen in 1273 and
877. Some calculations suggest that on a previous occasion it might have
split in two, with the larger fragment returning in 1532.

The comet can be found by looking low in the western sky between about
7.15pm in early March and as late as 9pm by the first week of April.

It will travel in an arc through the faint constellation of Pisces, and can
best be seen by looking to the left of the easier-to-identify Pegasus star
pattern. By March 16 it will be below the constellation of Aries.

In ideal conditions looking through binoculars it may be possible to see two
separate tails, a bright one caused by dust from the comet and a fainter
bluer one created by gas.

Mr Scagell said there was no need to worry about Ikeya-Zhang hitting the
Earth - it will miss us by a comfortable 37m miles.

Copyright 2002, The Guardian

==============
(9) EARTH TO ASH IN A FLASH

>From Sunday Herald Sun, 10 March 2002
http://www.sun-herald.com/

GRAEME O'NEILL

COMETS and asteroids are making a splash, with news emerging of plans to
land a probe on a celestial rock in 2011 and research projects throwing
light on a catastrophic collision 64.8 million years ago.

Chicxulub, on Mexico's Yucatan peninsula, was Ground Zero for the greatest
cataclysm of the past 200 million years.

At literally astronomical odds, an asteroid or comet looping around the Sun
intersected the Earth's orbit at a velocity of 110,000 km/h.

The mountain-sized object would have taken only four seconds to punch
through the stratosphere.

The Hollywood special effects sequences of enormous, fiery rocks tearing
across the sky seen in the Deep Impact blockbuster did not quite convey the
speed and magnitude of the spectacle.

Too small, too slow, and the Big One probably came in near-vertically, not
at a shallow angle.

It slammed into the shallow Caribbean Sea, vaporising the water and the
limestone sea bed, then melting or pulverising the underlying oceanic rocks
to a depth of 7km.

A tidal wave, initially about 5km high, spread out at supersonic speed from
the impact zone, and surged 200km inland.

It pulverised the nearby coastal zones of North and South America, and
traversed the then-narrow Atlantic seaway to devastate the western coast of
Europe and Africa.

A 2000km/h shock wave ripped through the lower atmosphere, momentarily
heating it to 2500C, and causing gaseous nitrogen to react with the hydrogen
and oxygen in water vapour, forming nitric acid.

For months afterwards the Earth's surface was deluged by a hard, acid rain
that changed the chemistry of lakes and waterways, caused marine food chains
to collapse.

The blast spawned an environmental holocaust that extinguished at least 70
per cent of the world's animal and plant species, including the dinosaurs.

It left a huge circular scar centred on Chicxulub.

The initial crater was probably no more than 100km in diameter, but it
widened as its steep edges collapsed.

Beyond the crater, fracture lines radiated out to a diameter of almost
300km. It remains a mystery as to whether the extraterrestrial assassin was
a large, icy comet about 15-17km in diameter, or a smaller, rocky asteroid
7km to 10km wide.

A drilling project near the village of Merida, on the Yucatan peninsula, may
resolve the issue.

The $3 million Chicxulub Scientific Drilling Project is a joint Mexican-US
operation, led by the geologists from the National Autonomous University of
Mexico, and involving researchers from the University of Arizona.

Late last month, the drilling project was proceeding at a rate of almost 50
metres a day and was rapidly approaching its target depth of 1.8km.

Things have come full circle at Chicxulub. It was during a routine an
oil-drilling survey in the 1930s that geologists first encountered strange
minerals and structures in the rocks.

The anomalies remained a mystery until 1991, more than a decade after Nobel
laureate physicist Luis Alvarez and his geologist son Walter proposed that a
thin layer of clay found in rocks in a mountainous area near Gubbio, Italy,
represented the global fallout from an extraterrestrial impact that wiped
out the dinosaurs.

Most of their peers dismissed the theory as outrageous, but satellite images
confirmed the presence of an enormous, circular structure beneath the
Yucatan peninsula. It is betrayed by the presence of a huge, circular
arrangement of wells, locally called cenotes, formed when limestone caves
collapsed and were filled by rain.

The immediate cause of the extinctions at the end of the Cretaceous period
is now known beyond reasonable doubt: an asteroid or comet impact.

But what happened after the impact to cause the global wave of plant and
animal extinctions has been the subject of much debate. Some scientists
think the extinctions were caused by an "asteroid winter", as fine dust
pulverised by the impact spread through the stratosphere, blocking out
sunlight.

In the resulting deep-freeze conditions, plant photosynthesis would have
halted, severely disrupting food chains.

But there may have been few plants left to photosynthsise.

Black, sooty fallout mixed with the fine, greenish clay that marks the end
of the so-called Cretaceous-Tertiary (K-T) period at sites such as Stevns
Klint in Denmark, attests to a firestorm, ignited by the intense heat of the
passing shock wave, and a rain of incandescent droplets of glassy material
that condensed from vaporised minerals.

Rounded, glassy particles called spherules are abundant in the K-T layer.
Soot deposits have been found in the K-T layer at sites across the world,
including in New Zealand, which is almost as far away from from Stevn's
Klint and Chicxulub as it is possible to be.

The conflagration was clearly global in extent, and caused most of the
world's forests to burn down.

A paper published in the February 22 edition of Science chills the "asteroid
winter" theory with an analysis of the pulverised rock thrown into the
atmosphere by the Chicxulub impact.

US geologist Kevin Pope has studied the size of particles thrown up when the
comet or asteroid hit Earth.

The heaviest were great boulders weighing 40 tonnes that rained down several
hundred kilometres from the crater.

They formed a geological feature called the Big Boulder Bed, exposed on
eroded hillsides on the Caribbean island of Haiti.

The finest particles, and the last to rain down out of the atmosphere,
formed a layer about 3mm thick on top of the K-T layer.

The largest particles in this thin layer are shattered quartz grains about
0.005mm in diameter.

DR Pope's analysis showed that the number of larger particles dropped off
sharply as the distance from the crater increased. It was as if they had
dropped from relatively nearby clouds, rather than being blasted into the
stratosphere and spread around the globe.

Dr Pope also found that there were not enough of the smallest particles to
have blocked out sunlight.

The light level would have been similar to that seen on a dull winter's day
in Seattle rather than that experienced in the depths of a Scandinavian
winter.

The concentration of atmospheric dust, in short, would have been 100 to 1000
times less than that needed to halt photosynthesis.

Undoubtedly, it reduced photosynthesis, but the real culprit is more likely
to have been the sudden loss of most of the world's vegetation in the
firestorm that immediately followed the impact, and the effect of the global
pall of dense smoke on light levels at the Earth's surface.

Further insights into the chemistry and structure of comets should be gained
when a European spacecraft attempts to land a probe on one in 2011.

The European Space Agency's Rosetta probe will chase the 1km-wide Comet
Wirtanen as it accelerates towards the Sun, and will release a probe that,
with luck, will land on the surface.

Comet Wirtanen is a pipsqueak compared with the source of the K-T impact.

It is a sobering thought that the impact of a 1km-wide comet anywhere on
Earth today would bring civilisation to its knees.

Try to imagine, then, the destructive power of the object that came down in
the Caribbean 64.8 million years ago.

Copyright 2002, Sunday Herald Sun

============================
* LETTERS TO THE MODERATOR *
============================

(10) CHANCES OF DYING FROM AN IMPACT

>From Michael Paine < mpaine@tpgi.com.au >

Dear Benny

I am puzzled by the apparent quote from Al Harris that the chances of dying
from an asteroid impact are about one in a million. In the early 1990s,
Morrison and Chapman estimated 1 in 20,000 (~3,000 fatalities per year) and
estimates of risk have changed little since then. The estimated number of
1km+ NEAs (note A for asteroid - comets are not included) has reduced by
perhaps half and the number of undetected 1km+ NEAs is now perhaps one
quarter of the M and C estimates (assuming the US Spaceguard program is at
the halfway point). This suggests the chances have "improved" to about 1 in
80,000. One the other hand, this assumes that all of the risk is due to 1km+
asteroids. More recent work has highlighted the risk from smaller objects
and from comets.
For example a one million year simulation that I conducted with John Lewis's
HAZARDS software
( http://www4.tpg.com.au/users/tps-seti/sta1046.htm ) came up with an average
annual death toll of 7500. Of these only about 3000 were due to 1km+
asteroids that are targetted by US Spaceguard.
3000 were due to one (unlucky) comet impact and the remaining 1500 were due
to sub-1km impactors. That simulation assumed there was no Spaceguard
program. We can (very roughly) estimate the benefits of a US-style
Spaceguard program by applying the estimated "completeness" after 10 years:

Impactor Annual Completeness Revised
Fatalities after 10 yrs
Annual Fatalities
Asteroid <200m 500 2% 500
Asteroid 200m to 500m 500 30% 300
Asteroid 500m to 1km 600 50% 300
Asteroid 1km+ 3000 90% 300
Comet (usually 1km+) 3000? <1%? 3000
----
----
7600
4400

This is on the basis that the Spaceguard program does not actually find a
NEA that will impact the Earth but simply reduces the magnitude of the
threat through elimination of 90% of 1km+ NEAs and a minor proportion of
smaller NEAs as potential impactors.

For comparison, the worldwide fatalities from earthquakes, averaged over
many decades, is about 10,000 per year and that from commerical airliner
crashes is about 700 per year (but, of course, a typical US citizen is
exposed to greater risk of dying in a plane crash than most of the rest
of the world).

Based on Ted Bryant's book, the death toll from from tsunami (probably NOT
impact generated) works out at about 300 per year over the past 2000 years.

These are interesting statistics that rank that NEO threat against other
causes of death. However, they don't get across the point that NEO impacts
are probably the only natural disaster that could bring down our global
civilisation. Since they are predictable and, to some extent,
preventable, it would be grossly negligent for our generation to not take
steps to try and reduce the risk.

regards
Michael Paine

=====================
(11) UNDERESTIMATING THE IMPACT HAZARD FROM SMALLER NEOs?

>From Jens Kieffer-Olsen < dstdba@post4.tele.dk >

"My real worry is that too many people will get frantic about the
impact hazard. ... I actually think we're doing about as much as we
should."
--Alan Harris, 27 February 2002

Dear Benny Peiser

You probably highlighted THE sentence from the Williams article.

The suspicion that one could be forgiven for harbouring is that the
medium-size NEO impact risk is a hush-hush area, which is being addressed in
Keyhole-context rather than in the public domain.

Let's consider the three categories of impact from a US point of view:

1. The larger-than-1km objects have a global impact. The world MUST react if
at all possible, and there will be unanimous backing in the UN to any
undertaking the USA might offer. The discovery
of an asteroid due to impact half a century or so from now will be a boost
to American industry and morale. Go get it!

2. The smaller-than-300m objects cause severe damage locally. Odds are that
the US will not be hit first time, and even if the impact DID take place in
the United States the country will preserve its international position and recover.
Business as usual!

3. The regional disasters caused by medium-sized objects NEED to be avoided
at all costs, if North America is the target area. - But would it justify
the gigantic cost and efforts, if bound to destroy say Australia?
Top-secret!

Let's be optimistic and work hard to ensure that the 10,000 or so category 3
objects will be mapped in an OPEN program, which must be initiated well
before the mapping of category 1 objects is deemed complete and funds correspondingly
reduced.

Subscribers to CCNet will undoubtedly agree that it is also cost-justified
to keep tabs on category 2 objects, but let's face the sad fact that it will
take several decades at least to build up the political will for funding
such an endeavour.

Yours sincerely
Jens Kieffer-Olsen, M.Sc.(Elec.Eng.)
Slagelse, Denmark

=================
(12) AND FINALLY: FED OFFICIAL DUBS US SLUMP THE "PLUTO RECESSION"

>From Reuters, 8 March 2002
http://biz.yahoo.com/rf/020308/n08133388_1.html

By Caren Bohan

ST. LOUIS, March 8 (Reuters) - Amid the was it or wasn't it debate about the
U.S. recession, a senior Federal Reserve official has coined a new phrase
for the economic downturn that began last March, dubbing it: ``the Pluto
recession.''

Speaking to a group of reporters on Friday, St. Louis Fed President William
Poole likened the controversy over how to describe the U.S. economy's recent
woes to the wrangles among astronomers about the planet Pluto.

``The astronomers argue about whether Pluto is or is not a planet,'' Poole
said. ``It's a marginal object. Some astronomers say Pluto is a planet and
other astronomers say Pluto is not a planet...Any time you have an event
that is out on the borderline, by definition it's not so clear.''

Tiny, cold Pluto, the smallest and most distant planet in the solar system,
has been the subject of frequent astronomical debate with an attempt as
recently as 1999 to reclassify it as asteroid No. 10,000.

Because of the similarities in the debates, Poole said, ``I think we're
going to end up calling this the Pluto recession.''

The National Bureau of Economic Research, an elite private group that is
viewed by most economists as the arbiter of U.S. business cycles, has
declared that a recession started in March of last year.

Even though the economic numbers have brightened lately, NBER has not yet
ruled on when the recession ended.

In the meantime, however, recent data on U.S. gross domestic product show
that GDP only experienced one quarter of contraction, a drop of 1.3 percent
in the third quarter of 2001. GDP, regarded as the broadest gauge of
national economic activity, in both the second and fourth quarters of last
year was positive, although in the second quarter it was only marginally in
the plus column, up 0.3 percent.

That puts the NBER -- which uses a broader set of indicators that does not
include GDP -- at odds with the short-hand definition used by some
economists of a recession as two straight quarters of falling output.

That has prompted some private economists as well as a few officials in the
Bush administration to question whether a recession really occurred.

Still another group of economists are willing to give the NBER the benefit
of the doubt, but are using words like ``recessionette'' and
``mini-recession'' to describe the recent economic episode in which 1.4
million people lost jobs.

Poole, who spent his career as an academic economist before joining the Fed,
said that when the dust settles, he'll side with whatever call the NBER
makes.

``Whatever I say -- it is or isn't -- it's going to go down in history as
what the National Bureau says it is,'' Poole said.

Copyright 2002, Reuters

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