South African scientists and collaborators from around the world have recently discovered the first ever evidence that suggests a comet has hit the Earth. Millions of years ago a comet entered Earth’s atmosphere, exploded, then rained down it’s fiery debris which destroyed everything in its path. This recent discovery in the Sahara, which will soon be published in Earth and Planetary Science Letters, could help scientists understand the early secrets of our solar system’s formation. The recently discovered evidence of the comet had entered Earth’s atmosphere some 28 million years ago. As it entered the atmosphere it exploded just above Egypt. As it got closer it heated the sand beneath it to about 2000 degrees Celsius. This caused the sand to form into yellow silica glass which was spread out over a 6000 square kilometer area in the Sahara. Interestingly enough, some of this yellow glass was polished by ancient jewelers and used in Tutankhamun’s brooch.
A strange black pebble found years earlier by an Egyptian geologist in the area of the silica glass is what sparked this whole investigation. After several chemical analyses the possibility of it being a meteorite was ruled out in favor of it being the first ever specimen of a comet’s nucleus.
But a little black pebble isn’t the only result of the impact. The explosion also produced microscopic diamonds. “Diamonds are produced from carbon bearing material. Normally they form deep in the Earth, where the pressure is high, but you can also generate very high pressure with shock. Part of the comet impacted and the shock of the impact produced the diamonds,” says Jan Kramers of the University of Johannesburg.
Material from comets have only been been found in the atmosphere and as microscopic particles. Carbon-rich comet dust has also been found in Antarctic ice. So this recent discovery has excited and reimagined the way scientists study comets.
“Comets contain the very secrets to unlocking the formation of our solar system and this discovery gives us an unprecedented opportunity to study comet material first hand,” says Professor David Block of Wits University.
The research was conducted by a collaboration of geoscientists, physicists and astronomers including David Block, lead author Professor Jan Kramers of the University of Johannesburg, Dr Marco Andreoli of the South African Nuclear Energy Corporation, and Chris Harris of the University of Cape Town.
Information provided by Wits University