An asteroid with a diameter of 500 km. Destination: The Pacific Ocean. The impact peels the 10 km crust off the surface. The shockwave travels at hypersonic speeds. Debris is blasted across into low Earth orbit, and returns to destroy the surface of the Earth. The firestorm encircles the Earth, vaporizing all life in its way. Within one day, the surface of the Earth is uninhabitable. The evidence shows that this has happened at least six times in Earth’s history.