That planet or moon would have to have a functioning magnetic field and consistent temperature. The farthest you could probably make it work is Jupiter, and even then those moons are covered in it's shadow for a long time and are bombarded by its deadly radiation.

That leaves Mars, which can't sustain an atmosphere because of it's weak magnetic fields, and was actually once like Earth but could not support itself, or Venus, which is a sulfur acid hellscape of unimaginable atmospheric pressure, and is surprisingly the best option considering it's the closest thing we have to a twin.

I don't know throwing water rocks at it would help much though.