[meteorite-list] Tut's gem hints at space impact

From: Mike Groetz <mpg444_at_meteoritecentral.com>
Date: Thu Jul 20 12:52:16 2006
Message-ID: <20060720165213.98866.qmail_at_web32902.mail.mud.yahoo.com>

Tut's gem hints at space impact

http://news.bbc.co.uk/2/hi/science/nature/5196362.stm

 Thing of beauty: Tutankhamun's Pectoral with desert
glass scarab Tutankhamun's gem

In 1996 in the Egyptian Museum in Cairo, Italian
mineralogist Vincenzo de Michele spotted an unusual
yellow-green gem in the middle of one of Tutankhamun's
necklaces.
The jewel was tested and found to be glass, but
intriguingly it is older than the earliest Egyptian
civilisation.

Working with Egyptian geologist Aly Barakat, they
traced its origins to unexplained chunks of glass
found scattered in the sand in a remote region of the
Sahara Desert.

But the glass is itself a scientific enigma. How did
it get to be there and who or what made it?

Thursday's BBC Horizon programme reports an
extraordinary new theory linking Tutankhamun's gem
with a meteor.

Sky of fire

An Austrian astrochemist Christian Koeberl had
established that the glass had been formed at a
temperature so hot that there could be only one known
cause: a meteorite impacting with Earth. And yet there
were no signs of an impact crater, even in satellite
images.

American geophysicist John Wasson is another scientist
interested in the origins of the glass. He suggested a
solution that came directly from the forests of
Siberia.

"When the thought came to me that it required a hot
sky, I thought immediately of the Tunguska event," he
tells Horizon.

In 1908, a massive explosion flattened 80 million
trees in Tunguska, Siberia.

Although there was no sign of a meteorite impact,
scientists now think an extraterrestrial object of
some kind must have exploded above Tunguska. Wasson
wondered if a similar aerial burst could have produced
enough heat to turn the ground to glass in the
Egyptian desert.

Jupiter clue

The first atomic bomb detonation, at the Trinity site
in New Mexico in 1945, created a thin layer of glass
on the sand. But the area of glass in the Egyptian
desert is vastly bigger.

Whatever happened in Egypt must have been much more
powerful than an atomic bomb.


 Boslough's specialism is modelling large impacts
Impact simulation

A natural airburst of that magnitude was unheard of
until, in 1994, scientists watched as comet
Shoemaker-Levy collided with Jupiter. It exploded in
the Jovian atmosphere, and the Hubble telescope
recorded the largest incandescent fireball ever
witnessed rising over Jupiter's horizon.
Mark Boslough, who specialises in modelling large
impacts on supercomputers, created a simulation of a
similar impact on Earth.

The simulation revealed that an impactor could indeed
generate a blistering atmospheric fireball, creating
surface temperatures of 1,800C, and leaving behind a
field of glass.

"What I want to emphasise is that it is hugely bigger
in energy than the atomic tests," says Boslough. "Ten
thousand times more powerful."

Defence lessons

The more fragile the incoming object, the more likely
these airborne explosions are to happen.

In Southeast Asia, John Wasson has unearthed the
remains of an event 800,000 years ago that was even
more powerful and damaging than the one in the
Egyptian desert; one which produced multiple fireballs
and left glass over three hundred thousand square
miles, with no sign of a crater.

"Within this region, certainly all of the humans would
have been killed. There would be no hope for anything
to survive," he says.


According to Boslough and Wasson, events similar to
Tunguska could happen as frequently as every 100
years, and the effect of even a small airburst would
be comparable to many Hiroshima bombs.
Attempting to blow up an incoming asteroid, Hollywood
style, could well make things worse by increasing the
number of devastating airbursts.

"There are hundreds of times more of these smaller
asteroids than there are the big ones the astronomers
track," says Mark Boslough. "There will be another
impact on the earth. It's just a matter of when."



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Received on Thu 20 Jul 2006 12:52:13 PM PDT