Ok, first off, you have to go here.
Ok, from the web page that just popped up you can have a little target practice with celestial bodies!
My first attempt assumes I'm still in Colorado and I drop a 500 meter chunk of rock on Virginia with some common speeds and angles. (swoon)
Ok, the results are that I could make a 30+ mile across hole in Virginia, thermally kill everyone here, and the chances are slim that anyone in Colorado would even notice.
I really like this web site. 😉