Pretoria - South African scientists have discovered the first evidence of a comet that exploded in the Earth’s atmosphere 28 million years ago, raining down fire and minute diamonds.
Wits University said on Tuesday the discovery provided the first definitive proof of a comet striking Earth.
David Block, a Wits professor and director of the university’s Cosmic Dust Laboratory, said: “Comets always visit our 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 the atmosphere above Egypt and exploded, heating up the sand beneath it to a temperature of about 2 000°C, creating a massive layer of yellow silica glass which still lies scattered over 6 000km² in the Sahara.
Wits said a “magnificent specimen” of this glass, polished by ancient jewellers, formed part of Tutankhamun’s brooch.
The research, which will be published in Earth and Planetary Science Letters, was conducted by a collaboration of geoscientists, physicists and astronomers, including Chris Harris, of Geological Sciences at UCT, Block, Jan Kramers, of the University of Johannesburg, and Marco Andreoli, of the South African Nuclear Energy Corporation.
A focus of the research had been a “mysterious black pebble” found years earlier by an Egyptian geologist in the area of the silica glass. After conducting chemical analyses on this pebble, the authors concluded that it was the very first known specimen of a comet nucleus, rather than a type of meteorite.
Kramers said the impact of the explosion had also produced microscopic diamonds. - Pretoria News