Comets probably won't cause the end of life as we know it: study

Crashing comets probably won't cause the end of life as we know it, a study said Thursday.

Astronomers at the University of Washington used computer simulation to model the evolution of comet clouds in the solar system over the past 1.2 billion years.

The simulation allowed them to peer into the Oort Cloud, a remnant of the nebula from which our solar system was formed.

"For the past 25 years, the inner Oort Cloud has been considered a mysterious, unobserved region of the solar system capable of providing bursts of bodies that occasionally wipe out life on Earth," said study author Nathan Kaib.

But the simulation found the Earth has likely only sustained two or three significant hits from comets in the past 500 million years.

Those comets may have spurred the late Eocene extinction -- a "minor event" by evolutionary standards -- which occurred about 40 million years ago.

But if that's the case, Kaib said that was probably the most intense comet shower since the fossil record began.

And the infrequency of the strikes "makes these phenomenon an improbable cause of additional extinction events," concluded the study published in the journal Science.

Comet strikes are very rare in party because the gravitational fields of Saturn and Jupiter can eject them into interstellar space or drag them crashing into the giant plants.

Disaster movie writers can take heart, however. The study doesn't preclude the threat of a massive asteroid strike, which is believed to have ended the dinosaur era.

Agence France-Presse - 7/30/2009