Scientists Find First Evidence of Comet's Impact with Earth - A Black Pebble Filled with Diamonds

A team of scientists have discovered the first evidence of a comet's impact on Earth in the form of a small black pebble filled with diamonds.

The unique pebble was discovered in an area of fused glass, the Libyan Desert Glass area spread over around 6,000 square kilometers. It attracted the attention of a geologist due to its unusual features as well as the lack of any corresponding rock formations. Laboratory analysis by the researchers from the University of Witwatersrand revealed that the rock was indeed quite unusual.

Professor David Block 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. 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."

The bulk of the pebble's material is carboniferious with a few silicates mixed in. The researchers, however, also found that interspersed with the material were millions of tiny diamonds. These are generally found on Earth in rocks that have been subjected to very high pressures, but the researchers posit that the same materials may be generated in an exploding comet.

Their paper, which was published in Earth and Plantary Science Letters, says that about 28 million years ago, a comet entered Earth's atmosphere over Egypt and exploded. The pressure of the explosion formed the diamonds in the pebble and the resulting heatwave created the Libyan Desert Glass.

Geologists had previously believed that the glass was formed by a meteorite impact, however the new evidence suggests that a comet is actually to blame.

The paper's author, Jan Kramers, also suggests that the discovery may have just saved a few space agencies some significant money, noting:

"NASA and ESA (European Space Agency) spend billions of dollars collecting a few micrograms of comet material and bringing it back to Earth, and now we've got a radical new approach of studying this material, without spending billions of dollars collecting it."

Many comets are believed to have crashed into Earth's atmosphere, however the pebble, which is known as "Hypatia" after the first recorded female mathematician Hypatia of Alexandria, is the first direct proof of a comet raining down on Earth.