Comets Could Spell Doom for Life in Space

Some stars have a high level of comet activity around them, and that could spell doom for any life trying to take root on any local planets. Ongoing research is trying to determine what fraction of stellar systems may be uninhabitable due to comet impacts. Many of our own solar system's comets are found in the Kuiper Belt, a debris-filled disk that extends from Neptune's orbit (30 AU) out to almost twice that distance. Other stars have been shown to have similar debris disks. "The debris is dust and larger fragments produced by the break-up of comets or asteroids as they collide amongst themselves," says Jane Greaves of the University of St. Andrews in Scotland.Roughly 20 percent of nearby sun-like stars have debris disks that are more substantial than our Kuiper Belt, according to data from the Spitzer space telescope.