Comet rained fire on Earth 28 million years ago, study says

Twenty eight million years ago a giant comet smashed into Earth and exploded in the atmosphere.

The explosion rained fire over modern day Africa and left a layer of silica glass over the Sahara desert.

The glass was formed as the comet's fire heated up the sands of the Sahara.

Further evidence of the cataclysmic event were lacking until now.

South African scientists said that they have found the first evidence of the comet in the form a small black pebble.

The pebble was discovered by an Egyptian geologist several years ago but chemical analyses were only recently completed.

Scientists found that the black pebble was part of the comet's nucleus and is the first such specimen ever discovered 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,” said Professor David Block of Wits University in a statement.

"If you compare it with meteorites … they contain only about three per cent carbon. And this thing contains 65 per cent carbon," he said, according to AFP.

Scientists believe that the findings will not only help to better identify similar rocks but also help us learn more about planets and their origins.

One interesting fact is that yellow silica created by the impact was found in ancient jewellery in the tomb of King Tut.

The research will be published in the journal Earth and Planetary Science Letters.