A study has suggested that the vast majority of asteroids in our Solar System may have a common origin – a handful of ancient planets.
Published in the journal Nature Astronomy, the study by the University of Florida suggests that 85 percent of the 200,000 asteroids in the inner asteroid belt come from five or six ancient minor planets. The remaining asteroids may come from the same place too, although that’s not known yet.
The researchers used models to trace the asteroids back to five families that surround large objects called Flora, Vesta, Nysa, Polana, and Eulalia. They suggest they began as “large primordial planetesimals”, or minor planets, which broke apart in the early days of the Solar System more than 4 billion years ago.
Of particular interest is learning how these asteroids evolved over time, and tracing back their history can give us a better picture. This can also tell us what materials they might be made of, so that if any rocks made their way towards Earth, we know what we’d be dealing with.
“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,” Stanley Dermott from the University of Florida, the study’s lead author, said in a statement.
“If ever one of these comes towards the Earth, and we want to deflect it, we need to know what its nature is.”
It’s not quite clear where the remaining 15 percent of the asteroids come from, but Dermott and his team suggest they may be the remains of other protoplanets, dubbed “ghost families”. Or, as mentioned, they may also come from one of these other ancient minor planets.
“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,” Dermott added in the statement.
There are 400,000 asteroids in the entire asteroid belt between Mars and Jupiter, so there is still some way to go to work out where they all came from. But this somewhat surprising study suggests that, despite the large number, they may have come from a similar place.