Washington: Researchers have discovered the first ever evidence of a comet entering Earth`s atmosphere and exploding, raining down a shock wave of fire that obliterated every life form in its path.
The discovery has not only provided the first definitive proof of a comet striking Earth, millions of years ago, but it could also help us to unlock, in the future, the secrets of the formation of our solar system.
Professor David Block of Wits University said that comets always visit the skies - they`re these dirty snowballs of ice mixed with dust - but never before in history has material from a comet ever been found on Earth.
The comet entered Earth`s atmosphere above Egypt about 28 million years ago. As it entered the atmosphere, it exploded, heating up the sand beneath it to a temperature of about 2 000 degrees Celsius, and resulting in the formation of a huge amount of yellow silica glass which lies scattered over a 6,000 square kilometre area in the Sahara.
A magnificent specimen of the glass, polished by ancient jewellers, is found in Tutankhamun`s brooch with its striking yellow-brown scarab.
At the centre of the attention of this team was a mysterious black pebble found years earlier by an Egyptian geologist in the area of the silica glass.
After conducting highly sophisticated chemical analyses on this pebble, the authors came to the inescapable conclusion that it represented the very first known hand specimen of a comet nucleus, rather than simply an unusual type of meteorite.
The research is set to be published in Earth and Planetary Science Letters.