The Nucleus of an Ancient Comet Was Found in Egypt

The Great Comet of 2007, a totally unrelated but equally cool comet, via Soerfm/Wikipedia

Scientists from the University of Johannesburg have discovered a pebble with an incredible history. Its unique composition and appearance—described as “angular, black, shiny, extremely hard, and intensely fractured”—has led the team to conclude that it is the first macro-sized chunk of a comet nucleus ever recovered on Earth.

“It’s a typical scientific euphoria when you eliminate all other options and come to the realization of what it must be,” said Professor Kramers, a lead author on the study. “Comets always visit our skies but never before in history has material from a comet ever been found on Earth,” added co-author Professor David Block. The team will present a public lecture about the finding at the University of the Witwatersrand on October 10.

The South African team nicknamed the stone “Hypatia” after the influential female philosopher and mathematician Hypatia of Alexandria (ca. 335-405). Like its trailblazing namesake, Hypatia the Pebble is Egyptian. It was found in the Libyan Desert Glass strewnfield in the southwest region of the country, near the border with Libya.

The strewnfield was formed 28.5 million years ago, by a comet that exploded over Egypt in a massive airburst, roasting the desert sand to temperatures of 2,000 degrees Celsius. Huge deposits of silica glass were created from the fiery shock wave, some of which ended up adorning King Tutankhamen's famous scarab broach.

King Tut's broach, with a scarab beetle made from the desert glass strewn field. Photo: Jon Bodsworth

“The impact of the explosion also produced microscopic diamonds,” said Kramers. “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.” Using a number of techniques including X-ray diffraction and Raman spectroscopy, the Johannesburg team discovered that Hypatia contains patches of these sub-micrometer diamonds.

They also discovered plenty of evidence that the stone is extraterrestrial in origin, including Hypatia's similarity to samples recovered from Comet 81P/Wild during NASA's Stardust mission. “NASA and ESA spend billions of dollars collecting a few micrograms of comet material and bringing it back to Earth,” said Kramers of the ambitious 1999 mission. “Now we’ve got a radical new approach of studying this material, without spending billions of dollars collecting it.”

“Comets contain the very secrets to unlocking the formation of our Solar System,” said Block. “This discovery gives us an unprecedented opportunity to study comet material first hand.”

The team's findings will be published in Earth and Planetary Science Letters on November 15. And if you can stand the desert heat, the strewnfield might be an interesting place to visit. Walking among diamond-speckled glass chunks formed by a comet's swan song would definitely be an experience to remember.