[meteorite-list] King Tut's Gem Hints at Space Impact

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed Jul 19 17:04:42 2006
Message-ID: <200607192102.OAA12685_at_zagami.jpl.nasa.gov>

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

Tut's gem hints at space impact
BBC News
July 19, 2006

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.

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."

Horizon: Tutunkhamen's Fireball, made by TV6 Productions, is on BBC Two
at 2100 BST on Thursday, 20 July
Received on Wed 19 Jul 2006 05:02:12 PM PDT