Asteroids aren't exactly thought of as the harbingers of life. In fact, it's quite the opposite, asteroids are what killed the dinosaurs and countless other species before them and it's what killed humankind in more Hollywood flicks than you can count.
But a new theory says that asteroids may be more important to life than thought before. In fact, they may be crucial and may be a determining factor in whether a planet develops life or not, especially advanced or intelligent life.
For one, asteroids bring water and organic material to nascent planets, creating the conditions for life to appear. Furthermore, asteroids may actually spur evolution, by literally stirring things up.
A huge asteroid hitting a planet creates new conditions to which life must adapt to by evolving, this is called the punctuated equilibrium theory.
The Monthly Notices of the Royal Astronomical Society is publishing a paper by Rebecca Martin, a NASA Sagan Fellow from the University of Colorado in Boulder, and astronomer Mario Livio of the Space Telescope Science Institute in Baltimore, Md which suggest that asteroid belts at just the right distance are crucial for life.
"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," Martin, the study's lead author, said. "Our study suggests that our solar system may be rather special."
They put together several theoretical models and, along with historical data, concluded that life needs a Jupiter-sized planet and the asteroid field it creates, by not enabling smaller planets to form due to its huge gravity, to flourish.
In fact, the conditions have to be just right, a planet that is too small, or too far away, or that moves too much or too little would be inappropriate.
"To have such ideal conditions you need a giant planet like Jupiter that is just outside the asteroid belt [and] that migrated a little bit, but not through the belt," Livio explained.
"If a large planet like Jupiter migrates through the belt, it would scatter the material. If, on the other hand, a large planet did not migrate at all, that, too, is not good because the asteroid belt would be too massive. There would be so much bombardment from asteroids that life may never evolve."