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Asteroid belt tells story of chaotic early Solar System

Charles Black, Founder and CEO of Sen
Jan 31, 2014, 8:00 UTC

Sen—A new map of the Solar System's asteroids provides evidence of a chaotic early period when the migration of the giant planets shook up the order of where the space rocks originally formed.

The study by researchers from MIT and the Paris Observatory, led by Francesca DeMeo, now a postdoctoral fellow at the Harvard-Smithsonian Center for Astrophysics (CfA), charts the size, composition and location of more than 100,000 asteroids throughout the Solar System. The research found that 'rogue' asteroids -- those found in a different location to where they formed -- are more common than previously thought.

"We found that the giant planets shook up the asteroids like flakes in a snow globe," explained DeMeo. A particularly diverse mix of asteroids were found in the main asteroid belt which lies between Mars and Jupiter. "It’s like Jupiter bowled a strike through the asteroid belt. Everything that was there moves, so you have this melting pot of material coming from all over the solar system,” said Francesca DeMeo, who did much of the mapping whilst at MIT’s Department of Earth, Atmospheric and Planetary Sciences. 

The new map suggests in the early Solar System Jupiter moved closer to the Sun, possibly as close as Mars is now, dragging with it asteroids that originally formed much further out in the colder parts of the Solar System. Jupiter's migration back to its present orbit probably dragged asteroids back which had formed closer to the Sun. 

To construct the map the researchers used data from the Sloan Sky Digital Survey. Asteroids were grouped by size, location and composition. An asteroid's origins -- whether it formed in a warmer environment closer to the Sun further out in the colder parts of the Solar System -- can be determined by whether an asteroid's surface is more reflective at redder or bluer wavelengths.

Objects from as close to the Sun as Mercury, and as far out as Neptune, all collected in the main asteroid belt. "The asteroid belt is a melting pot of objects arriving from diverse locations and backgrounds," explains DeMeo.

The pinballing of asteroids during the early years may have played a part in delivering water to Earth, as colder asteroids containing ice, which formed in the outer parts of the Solar System, were dragged inwards and impacted on Earth. “The story of what the asteroid belt is telling us also relates to how Earth developed water, and how it stayed in this Goldilocks region of habitability today” said DeMeo.

The research is published in the January 30, 2014 issue of Nature