Red Ice Membership

Tut's gem hints at space impact
2006 07 22

From: news.bbc.co.uk

Thing of beauty: Tutankhamun's Pectoral with desert glass scarab. Video available at: BBC.co.uk




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.


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



Jupiter clue



Boslough's specialism is modelling large impacts
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.

Barakat holds up one of the many, huge chunks of glass in the desert
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 production company TV6 is on BBC Two at 2100 BST on Thursday, 20 July

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

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