Gravity tractor

A gravity tractor is a big spaceship that hovers really close to an asteroid or comet and uses its own gravity to move it in a different direction. It works like a farmers tractor that pulls a plow: the spaceship is like the tractor and the asteroid or comet is like the plow! The gravity tractor is so powerful it can pull the asteroid without having to actually touch it. This is really helpful for keeping dangerous asteroids from hitting Earth!