Comet Formation Theory May Not Be Set In Stone (Or Ice)

Photo: CLOUDY ORIGINS: A comet called 2001 RX14 likely originated from a hypothesized region called the Oort cloud, far outside the planetary region of the solar system. A new model of how comets wind up near the inner planets may revise estimates of the Oort cloud's properties. Mike Solontoi/University of Washington

From Scientific American:

A new model for comet production revises the theory of their origins.

A few times a year, a visitor from deep space swings by Earth's neighborhood. Usually coming in peace, these interlopers pass by close enough to be seen, then continue on their way.

The uninvited guests are comets, streaky globules of ice and dust dislodged from one of their usual haunts far from the sun and planets: the Oort cloud. Named for Dutch astronomer Jan Oort, who hypothesized its existence in 1950, the theorized cloud is thought to contain billions or even trillions of comets that range out a few thousand to tens of thousands of times as far from the sun as Earth is. Oort cloud comets are occasionally nudged onto trajectories carrying them into the inner solar system by the passing of nearby stars or other interactions with the rest of the Milky Way Galaxy.

Read more ....