October 8, 2013
Just In Time For ISON: Scientists Discover Ancient Earth Comet Impact
[ Watch the Video: Ancient Earth Comet Impact Evidence ]
Lee Rannals for redOrbit.com - Your Universe Online
Comet ISON is getting closer to making its close pass by the sun, but what would happen if it had a brush with our planet instead? New evidence shows it would be devastating.
International scientists have discovered the first ever evidence of a comet entering Earth's atmosphere and exploding. This celestial object rained down fire across the Earth, obliterating every life form in its path.
The team's discovery provides the first definitive proof of a comet striking Earth millions of years ago. It also helps to give scientists a peak into how comets help shape the solar system.
"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," Professor David Block, of Wits University, said in a statement.
According to the findings, a comet entered Earth's atmosphere above Egypt 28 million years ago. As it made its way into the atmosphere, it exploded, heating up the sand beneath it to a temperature of about 3,600 degrees Fahrenheit, which resulted in the formation of a huge amount of yellow silica glass that scattered over a 3,700-square-mile area in the Sahara Desert.
An Egyptian geologist discovered a mysterious black pebble a few years ago, which the scientists used as part of their study. The team determined that this pebble, named "Hypatia," represented the first known hand specimen of a comet nucleus, rather than simply an unusual type of meteorite.
"It's a typical scientific euphoria when you eliminate all other options and come to the realization of what it must be," said Professor Jan Kramers of the University of Johannesburg and lead author of the paper published in Earth and Planetary Science Letters. 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."
She pointed out that NASA and the European Space Agency is spending billions of dollars to try and collect a few micrograms of comet material and bring it back to Earth, but "now we've got a radical new approach of studying this material, without spending billions of dollars collecting it."
Block said that comets contain the very secrets to unlocking the formation of our solar system. He added that this discovery gives scientists a new opportunity to study comet material first hand.