Eventually it will kill you, so gf example. Gf example-killer because 1,000,000,000,000 light years is an enormous distance that would hit another body of mass stopping it from reaching earth. What about a bullet shot from the ISS pointed away from earth because theres no friction the bullet would go forever onward. Maybe it'll hit space debris in our atmosphere and reflect back at you. :P We are in the Space Station or even the moon. The bullet would be at a high velocity so theres a possibility of it going through or pushing the object. @ the first one about the astroid, then the example is invalid as it has to be attempting to kill you. @ the 2nd one, a bullet shot in the sky? I guess it bouncing off of a plane and hiting you back with the force of gravity. What goes up must come down!