In article , "Kent Paul
Dolan" wrote:

And would the planetary friction be equally
negligible at this low density?

Well, there shouldn't be any "planetary friction",
as usually described, dark matter's _only_
interaction with normal matter is via gravity:

http://www.nasa.gov/home/hqnews/2006...rk_Matter.html

Not really, that is how it is discovered, not a description of all its
properties. See the post by .

--
Hans Aberg