The widely accepted history of the asteroid belt between the orbits of Mars and Jupiter is that the myriad objects are the remnants of a planet that began but failed to coalesce during the formation of the solar system. The millions of the objects in the belt failed to come together due to the massive disruption caused by Jupiter’s gravity. The compositions of the asteroids in the belt vary depending on the distance from the Sun.
However, according to a press release, a new study by Francesca DeMeo of the Harvard-Smithsonian Center for Astrophysics and Benoit Carry of Paris Observatory challenges that view. DeMeo and Carry poured over data from the Sloan Digital Sky Survey, a cosmological mapping project undertaken by around 150 scientists at institutions around the world. DeMeo and Carry focused on the compositions of thousands of objects in the asteroid belt. Their study revealed that the compositions of the asteroids, especially the smaller objects, are far more diverse than previously thought.
DeMeo and Carry’s findings suggest that, as the solar system was forming, the gas giants, such as Jupiter, careened inward towards the Sun and back out to where they now reside. The movement of Jupiter could have deprived the original asteroid belt of all but a tenth of one percent of its population, as the massive planet moved as close to the Sun as Mars is today. However, as the giant planets continued to migrate through the early solar system, they redirected objects from as near the Sun as Mercury and as distant as Neptune, forming the asteroid belt as we know it.
“The asteroid belt is a melting pot of objects arriving from diverse locations and backgrounds,” said DeMeo.
The new findings align with the idea that asteroid impacts brought most of Earth’s water early the planet’s evolution. The disruptions caused by the movements of the giant planets could have propelled those important asteroids towards Earth. However, this raises the troubling possibility that Earth-like exoplanets might also need an asteroid bombardment to deliver water; if similar disturbances caused by gas giants did not occur in many other solar systems, then habitable Earth-like exoplanets could be scarcer than surveys, such as Kepler, would suggest.
The new research has been published in the January 30 issue of the journal Nature.