The beachball-sized remains of the asteroid were drilled out of the 145-million-year-old Morokweng crater in South Africa. The crater was formed by an asteroid, around five to ten kilometres across, at the boundary of the Jurassic and Cretaceous periods.

The discovery has been reported in the journal Nature as the first finding of asteroid remains after such a large impact. Previous attempts to find asteroid remains at sites such as the Meteor Crater in Arizona, USA, failed. Scientists believed that this was because when asteroids strike the Earth, the heat produced is so great (between 1 700 - 14 000 degrees) that the asteroid completely melts or vaporises. The finding could teach us more about the processes that occur during impacts.

The remains were discovered near the centre of the crater, fused to Earth rock that was melted by the asteroid when it struck the surface.

"At about 770m down, we came across some dark blocks - one was about the size of a beachball - but we couldn't figure out what it was," said Marco Andreoli, an author on the Nature paper and a geologist at the South African Nuclear Energy Corporation and the University of Witwatersrand.

Further tests were performed on samples of the material and scientists were astonished to discover that it was a meteorite.

"What is amazing is that here we have these fragments - that may not have been attached to the asteroid, or maybe trailing behind it - that smashed into the Earth and survived the fiery furnace in the crater that formed; and then they got trapped," said Andreoli. "This is remarkable because this is something that people didn't think could happen. Anything that helps scientists to model what happens when two bodies collide is good news."

The sample is slightly different to other meteorites � it is a little more radioactive, and contains more uranium and sodium, but less iron and nickel.

"All of our science of meteorites is based on meteorites that fell in the last few thousand years, but all of a sudden we can study a meteorite that fell 145 million years ago, and this opens the possibility that the nature of these impacting bodies has changed over the years," Andreoli explained.