Ancient Wisdom: Early Universe Asteroids Hint at Our Solar System's Origins

Geronimo Vena
Agosto 5, 2017

"The family we identified has no name, because it is not clear which asteroid is the parent", said Kevin Walsh, astronomer at Southwest Research Institute in the U.S. and co-author of a study published online in the journal Science. The scientists now plan to use the same approach on other parts of the asteroid belt to dig even deeper into the early stages of our solar system.

Identifying the very oldest asteroid families, those billions of years old, is challenging, because, over time, a family spreads out, researchers said.

Most asteroid families are thought to have formed about 1billion years ago. Tens of thousands of these minor planets are gathered in the main asteroid belt, a vast doughnut-shaped ring between the orbits of Mars and Jupiter.

Asteroid families begin to disperse because of the way they are affected by the heat of the sun. Here, Marco Delbo' and colleagues have identified a group of dark asteroids with related orbits as part of a previously unknown family, which they estimate to be roughly 4 billion years old, making it older than most known families.

Interestingly, the team has used a new method to scope for these kinds of asteroids which involves looking for the "edges" of families that have drifted away the furthest in the belt.

"This family was indeed the largest missing piece of a huge puzzle", lead author Marco Delbo, an astrophysicist at the University of the Côte d'Azur in Nice, France, said in an email statement to Courthouse News.

"If you look for correlations of size and distance, you can see the shapes of old families", Delbo noted.

The space rocks in the main asteroid belt, between the orbits of Mars and Jupiter, are almost as old as the solar system itself, which formed about 4.6 billion years ago. "By identifying all the families in the main belt, we can figure out which asteroids have been formed by collisions and which might be some of the original members of the asteroid belt", Walsh said.

According to the gravitational collapse theory of asteroid formation, space dust smashed together nearly instantaneously to create planets, called planetesimals.

"We identified all known families and their members and discovered a big void in the main belt, populated by only a handful of asteroids. That is the real prize, to know what the main belt looked like just after it formed", Walsh noted.

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