Fantastic subject, i'm always thinking about our universe, why we are here, how we came to be etc etc etc!! Its truly fasinating stuff. 
Whats mad is that we are still here, yet there are loads of comets and asteriods hurtling through space, hitting our moon and surrounding planets, okay we've had a few impacts ourselves but nothing like the ones they've seen hit jupiter, apparantly one asteriod that hit jupiter was the size of the earth!! :S
Also they believe that at every centre of every galaxy is a mega super black hole, or something along those lines, and that is what keeps us all spinning around in harmony with each other. They can lie dormant for centuries then all of a sudden start feeding of our sun, sucking it up, bits at a time!!
Also we (planets, stars, gases etc) only make up 5% of the universe! We just can't see the other 95%!! :S
Love this subject!!
