Study reveals the ‘secret’ origins of asteroids that fly past Earth

'If ever one of these comes towards the earth, and we want to deflect it, we need to know what its nature is'

Most of the asteroids flying about above our heads came from a relatively small number of planets that broke up and were flung around our solar system, a new study has shown.

At least 85 per cent of the asteroids in the inner asteroid belt – where the meteorites that drop down to Earth usually come from – come from just five or six ancient small planets, the new research shows.

Those planets splintered up and separated into the asteroid belt that now sits in our solar system. Occasionally, one of those rocks makes its way out and flies towards the Earth.

Scientists are concerned that one of those large rocks could eventually find its way towards Earth, causing huge damage to the planet. Just last month, Nasa revealed how it is planning to respond to such a threat.

The new findings – published in Nature Astronomy – could help understand the nature of those dangerous asteroids and meteorites, the researchers said.

"These large bodies whiz by the Earth, so of course we're very concerned about how many of these there are and what types of material are in them," said Stanley Dermott, lead author and a theoretical astronomer at the University of Florida. "If ever one of these comes towards the earth, and we want to deflect it, we need to know what its nature is."

It could also help us understand the materials that came to shape our own planet.

The findings are true for some 85 per cent of the objects in the inner asteroid belt, which is made up of 200,000 objects. But it might apply to far more than that, said Professor Dermott.

"I wouldn't be surprised if we eventually trace the origins of all asteroids in the main asteroid belt, not just those in the inner belt, to a small number of known parent bodies," he said.