wouldn't a death star have its own gravity, yet have no atmosphere, meaning that astroids and stuff would constantly crash into it and the middle would be very hot?
To pull enough metal out of earth to even give this artificial planet gravity would pull gravity off the earth as well, not to mention how extremely long and difficult it would be to lug it up there.
It wouldn't have an atmosphere, and pumping air up there is also not an option. Especially since it would just drift away due to the lack of gravity.
Asteroids are pelting the Earth constantly, and that's with an atmosphere. They would certainly smash into this hunk of metal.