Thanks Ticho, I was about to say that :)

It's not like you can take the asteroids into account, you have to measure average density of 'empty space', where there are no concentrations of matter. But we're wildly off-topic. Sorry about that.

In response to the density of space in Sedina B-8, you'll have to forgive me, for I had a large burrito the other night and things got slightly out of hand. The resulting gas explosion should be fully cleared and the nebula dissapated within 30 of your Earth years.