Shooting star matched to meteorite

In a first for science, a shooting star has been matched with a meteorite found on earth.

The find offers an insight into how planets were formed as well as clues on how to avoid a future asteroid Armageddon, Associated Press reports.

Last October astronomers tracked the asteroid, dubbed 2008 TC3, as it hurtled towards earth, something they had not done before.

The space rock blew up into a fireball as soon as it hit the earth's atmosphere and it was presumed there would be nothing left by the time it hit the ground in northern Africa.

But a search by dozens of students through a remote desert in Sudan turned up 4kg of black jagged rocks, the remains of 2008 TC3.

Astronomers have for years lobbied to send a robot probe to an asteroid, take a sample and return it to Earth for analysis.

A study published today in the science journal Nature has now described the many surprises, including minuscule diamonds, that asteroids reveal.

"This was a meteorite that was not in our collection, a completely new material," the study's lead author, Peter Jenniskens of NASA's Ames Research Centre in California, said.

Scientists believe the asteroid is a leftover from a time when chunks of colliding rock tried and failed to become a planet about 4.5 billion years ago.

"It's a beautiful example of looking at an earlier stage of planet development that was arrested, halted," NASA cosmic mineralogist Michael Zolensky, a co-author of the study, said.

The finding also serves as a lesson for the future if a giant asteroid makes a path for earth.

Blowing up such a rock, as happens in the Bruce Willis movie Armageddon, would prove futile because the rock is like "travelling sandpile," said Zolensky, and so all the shattered pieces would just continue their trajectory for earth.

Another co-author, NASA's Simon Worden, said a spaceship-aided nudge would be more effective.

"The real important issue is to understand the physics of these objects," said Worden, who has long advocated for worldwide plan to deal with the threat of asteroids and comets hitting the planet.

However, 2008 TC3 belongs to a class of asteroids which are mostly porous and fragile and therefore are unlikely to pose any danger to Earth, even if it's bigger, University of Maryland astronomer Lucy McFadden said.

The asteroid was found to be full of metals, such as iron and nickel, and organics such as graphites. Perhaps most interesting are the "nanodiamonds" it carried.

These diamonds are formed by collisions in space and high pressure and they are all over the rocks, making them glitter like geodes, Zolensky said. But they are not at all big. "If bacteria had engagement rings, these would be the right size for them," Zolensky said.