[OldNavyVet]

"... and at the end the supposition was maybe this was much more common than we thought...."

From "Darwin's Ghost" by Steve Jones. page 218 ...

A trillion comets orbit the sun. The gravel that surrounds them appears, should it hit our atmosphere, as a shower of meteors. The Earth gains a ton in weight every hour from their dust. Two thousand asteroids big enough to destroy civilization orbit nearby.

[brytlea]

Yeah, I try not to think about it! ;)