All kidding aside, there are several facts that remain: (1) large (i.e., 1 mile in diameter or bigger) rocks have in the past hit the Earth, including during the time the Moon was present, (2) there are today a large number of such large rocks still floating around the Sun, which have orbits that bring them closer to, and further away from, the Sun, and thus the Earth, (3) there is no a priori basis for concluding that none of these large rocks could ever hit the Earth, and (4) we currently have no meaningful way of protecting ourselves from such a large rock.