Three possible scenarios for the evolution of asteroid belts. Top: A Jupiter-size planet migrates through the belt, scattering material and inhibiting the formation of life on planets. Middle: A Jupiter-size planet moves slightly inward but is just outside the belt (this is the model proposed for our solar system). Bottom: A large planet does not migrate at all, creating a massive asteroid belt. Material from the hefty asteroid belt would bombard planets, possibly preventing life from evolving.
Alien Life May Require Rare ‘Just-Right’ Asteroid Belts
Asteroid belts similar to the one between Mars and Jupiter appear to be rare beyond our solar system, implying that complex alien life may be rare as well, a new study reports.
Fewer than 4 percent of known alien solar systems are likely to have an asteroid belt like the one in our own neck of the woods, researchers found. Belts that look like ours may help spur the evolution of life, seeding rocky planets with water and complex chemicals but not pummeling the worlds with a constant barrage of violent impacts.
"Our study shows that only a tiny fraction of planetary systems observed to date seem to have giant planets in the right location to produce an asteroid belt of the appropriate size, offering the potential for life on a nearby rocky planet," study lead author Rebecca Martin, of the University of Colorado in Boulder, said in a statement. "Our study suggests that our solar system may be rather special."