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The second “Tunguska” catastrophe

10 Mar

About 480 thousand years ago in the skies over Antarctica, an event that is similar to the Tunguska catastrophe in 1908 – an explosion intruding into the atmosphere of outer body weight of hundreds of thousands of tons of European scientists have established.

The report presented at a conference on planetary and lunar exploration in Texas, Folk Luigi (Luigi Folio) from the University of Siena and his colleagues from France and Britain presented the results of the analysis of micro-spherical shape, found in Antarctica in the area of Victoria Land.

“The composition of these micro spheres indicates that they are of meteoritic origin” – the report says. The properties are close to one type of stony meteorite – carbonaceous chon rites.

Previous studies have shown the presence in some parts of Antarctica meteorite dust layers that were dated to ages 430 and 480 thousand years ago. Such layers were found during drilling of the ice sheet in East Antarctica project EPICA-Dome C and Dome Fuji.

Analysis showed a high degree of similarity of particles found in layers dated to the epoch of 480 thousand years, and particles found in Victoria Land. However, these two points are separated by a distance more than 2,9 thousand kilometers. This means that the meteorite was “sprayed” on the huge area that is comparable in size to the whole continent.

“Mathematical modeling showed that it was a stony meteorite weighing from 100 thousand to 100 million tons, which completely destroyed the entrance to the lower layers of Earth’s atmosphere, just as happened during the Tunguska event in 1908” – the scientists say. Then, 30 June 1908 in the Stony Tunguska River basin, in the current Evince flew and blew a fireball. In the area of the explosion was knocked down to the woods on an area approximately equal to the modern Moscow, but at the scene found no signs of falling, no debris of the cosmic body. Currently, most scientists believe that the Tunguska cosmic body – a stone meteorite, which exploded and completely evaporate before reaching the ground.

In addition, the study authors, simulations showed that at the last stage of destruction formed the so-called plume – “bubble” of hot gas, which moves in the opposite direction along the trajectory of the meteorite, made a particle of matter in the upper atmosphere. Since the particle space body were scattered over thousands of kilometers away.

Events such as the Tunguska catastrophe may occur about once every 500-1000 years. This means that the ice shield of Antarctica can find evidence of several more such disasters, the scientists conclude.

 
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Posted by on March 10, 2010 in Historical

 

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