First ever evidence of a comet entering and exploding in the Earth's atmosphere millions of years ago could help scientists solve mysteries of how the solar system once formed.

According to new research from the University of Witwatersrand and other international collaborators, the discovery is the first definitive proof of a comet striking Earth's atmosphere, which would have produced a powerful shock wave of fire.

"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 news release.

Scientists estimate the comet entered the atmosphere some 28 million years ago above Egypt. When it entered the atmosphere, hurdling toward Earth, the sand would have heated up to about 2,000 degrees Celsius. This is where the evidence lies, because of how hot the sand would have been, it would have formed a large amount of yellow silica glass, which is found scattered throughout the Sahara Dessert.

"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, of the University of Johannesburg, said.

The team's research began years ago with the discovery of an odd black pebble found by Egyptian geologists among the silica glass. Previously believed to be an ordinary meteorite, further chemical analysis revealed the strange pebble to be the nucleus of a comet.

"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," said Kramers. "Part of the comet impacted and the shock of the impact produced the diamonds."

The research team named the pebble "Hypatia" after the first well-known female mathematician, philosopher and astronomer, Hypatia of Alexandria.

Kramers said agencies like NASA and the European Space Agency spend billions in search of samples like the one they obtained. The researchers' work will be published in the upcoming edition of the journal Earth and Planetary Science Letters.

Said Block, "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."