A study in the journal Nature
throws a new light on this strip of our solar system, where most of the
asteroids in our solar system reside. Whereas scientists once believed
that these asteroids formed more or less in place, new modeling suggests
they have been scattered all over.
Scientists believe "the
asteroid belt is a melting pot of bodies that formed all over the solar
system," said Francesca DeMeo, lead study author and an astronomer at
the Harvard Smithsonian Center for Astrophysics.
Back in the 1980s, when
only about 10,000 asteroids were known, it seemed that asteroids that
appeared to have formed in a cold environment were farther away from the
sun, while those that formed in a hot environment were closer to the
sun.
But DeMeo and co-author
Benoit Carry of the Paris Observatory studied hundreds of thousands of
asteroids and they found that this trend did not hold. Instead they
spotted many "rogue" asteroids: Rocks formed in hot environments that
were in regions where cold-environment-formed asteroids were expected,
and so on.
The main asteroid belt is much more diverse than originally thought, the study shows. Dante Lauretta, lead scientist on the asteroid sample return mission OSIRIS-REx
and professor at the University of Arizona, said in an e-mail that the
study "represents a new paradigm in our understanding of the
compositional diversity of the asteroid belt." Lauretta was not involved
in the Nature study.
Although astronomers
cannot directly measure temperatures of asteroids, they can infer a
rock's origin through geology. For instance, an asteroid with a lot of
carbon probably formed far from the sun, in colder temperatures.
The theory is that the
planets of our solar system have moved over time. Jupiter, the largest
planet in our solar system and the one with the most gravitational pull,
had a big part to play. As Jupiter moved toward the sun, it scattered
asteroids, "like a snow globe," DeMeo said.
Over time, she said, there was "a big mess of asteroids everywhere." The only place for them to remain was the asteroid belt.
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