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Köfels in Austria, Rockslide

Asteroid Impact Mystery Solved by Ancient Clay Tablet

For those of us who enjoy the studies of the past – geology, archaeology, history, etc – there is nothing quite as intriguing as seeing one help solve the other. This is just the case in a recent revelation that has helped explain a mystery dating back to the 19th century. 

Köfels in Austria is the home to evidence of the largest rockslide in the crystalline Alps. The landslide measures in at 500m thick and five kilometers in diameter.

For a long time geologists have struggled to explain how it came about. Originally it was theorized in the middle of the 20th century that it was caused by a large meteor impact. However further research in to impact events showed that the landslide didn’t have the necessary characteristics to fit such an explanation; mainly, that there was no impact crater.

However thanks to new research by Alan Bond, Managing Director of Reaction Engines Ltd and Mark Hempsell, Senior Lecturer in Astronautics at Bristol University, an answer has arisen.

Another 19th century mystery – a cuneiform clay tablet that has puzzled scholars for over 150 years – has come to the rescue to provide a valid explanation of the event.

Located in the British Museum collection, No K8538 and known as “the Planisphere”, the cuneiform tablet was discovered by Henry Layard in the remains of the library in the Royal Palace at Nineveh. Made by an Assyrian scribe around 700BC, it is the astronomical work of a Sumerian astronomer.

The tablet has drawings of constellations inscribed on to it, as well as constellation names. But with modern technology allowing researchers to go back in time to view the night sky on any given day, time or year, a more precise indication of what the tablet has been saying all these years has given proof to the Köfels landslide mystery.

According to the researchers, it refers to the night sky observations of an astronomer, taken just before dawn on the 29th of June, 3132 BC (by the Julian calendar).

Half of the tablet records planet positions – which allowed the researchers to track the date so precisely – as well as cloud cover; attributes which were similar from night to night. However this particular tablet also records the existence of a large object, large enough to be noted while in space. The astronomer/s made an accurate note of its trajectory relative to the stars.

With an error better than one degree, these measurements match up with an asteroid that would soon impact at Köfels.

The ancient observations hint towards the asteroid being approximately one kilometer in diameter, with an Aten type orbit around the Sun (a class of asteroid that orbit close to the earth that is resonant with the Earth’s orbit).

However the existence of this not only proves an asteroid impact, but it explains why there is no impact crater.  The asteroid came in at a very low angle of only six degrees, and subsequently clipped a mountain called Gamskogel above the town of Längenfeld, 11 kilometres from Köfels. Thus, the asteroid exploded before it reached its final impact point, travelling the last stretch as a giant fireball about five kilometers in diameter; the same size as the landslide.

On impact with Köfels, the incredible pressure pulverized the rock and caused the landslide. However, because it was not a solid object at the time of impact, it did not create an impact crator.

Mark Hempsell, discussing the Köfels event, said: “Another conclusion can be made from the trajectory. The back plume from the explosion (the mushroom cloud) would be bent over the Mediterranean Sea re-entering the atmosphere over the Levant, Sinai, and Northern Egypt.

“The ground heating though very short would be enough to ignite any flammable material - including human hair and clothes. It is probable more people died under the plume than in the Alps due to the impact blast.”

HYPERLINK “http://www.eurekalert.org/pub_releases/2008-03/uob-cct033108.php” http://www.eurekalert.org/pub_releases/2008-03/uob-cct033108.php
HYPERLINK “http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/03/31/scitablet131.xml” http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/03/31/scitablet131.xml