A 28-million-year-old comet that collided with Earth over Egypt, killing all signs of life in its path has been identified by a team of scientists. The discovery is the first evidence of a comet striking Earth.
New research published in Earth and Planetary Science Letters reveals how the comet entered Earth’s atmosphere over Egypt, exploding and heating up the sand to a sweltering 3,632 degrees Fahrenheit. What remained became a 2,316 square mile area of yellow silica glass in the Sahara Desert known as Libyan Desert Glass -- a remnant of which was found in Tutankhamun’s brooch.
"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," David Block, an astronomy professor at Wits University, in Johannesburg, said in a statement.
Evidence of the comet’s existence lies in a black pebble found years ago by an Egyptian geologist in the silica glass. Researchers conducted chemical analyses including X-ray diffraction, Raman spectroscopy, transmission electron microscopy, among other methods to prove the pebble belonged to a comet, rather than a meteorite.
"It's a typical scientific euphoria when you eliminate all other options and come to the realization of what it must be," lead author Jan Kramers, a geology professor at the University of Johannesburg, said in a statement.
Described as “angular, black, shiny, extremely hard and intensely fractured,”the comet fragment, called Hypatia, contains diamonds -- a product of the comet’s shock it produced on earth.
"Diamonds are produced from carbon bearing material," Kramers explained. "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."
The comet’s diamond qualities are seen in its carbon makeup. "If you compare it with meteorites ... they contain only about three percent carbon. And this thing contains 65 percent carbon," Kramers told Agence France-Press about the comet fragment.
Finding comet fragments remains a challenge for scientists. Besides microscopic dust particles and some carbon-rich dust found in Antarctic ice, little comet material, if any, has been found on Earth.
"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," Block said.
But with the techniques used to identify Hypatia, this may soon change.
"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," Kramers said.