Hitting planets with comets

At 11:14 AM 5/6/97 -0500, you wrote:
>On Mon, 5 May 1997, Mikko Kurki-Suonio wrote:

>	So... let's apply what you said to planets... Mmmm... planet
cannot 
>move... so we track a hugh asteriod to drop on the planets.... we
should 
>get the same effect as nuclear winter or ice age on earth(If I am wrong

>feel free to correct me.). Therefor, planet is not really defendable 
>either... (I think some body else mentioned drop a hugh rock on planets

>too.) 
	To get an idea of just how bad it would really be to be hit by a
comet read the original story on the subject, Lucifer's Hammer.  You'll
find
it in many book stores with Niven's other work in the Science Fiction
section.