If a large extraterrestrial body, such as a comet or asteroid, with a diameter of six miles (10 kilometers) or more struck anywhere on our planet, land or sea, the impact would be felt worldwide. The initial impact would vaporize parts of the Earth’s crust, as well as the oceans, and send shockwaves out to every corner of the globe. Debris would be shot out into the upper atmosphere, and the heat generated from the collision with the atmosphere and crust would turn the sky red and set the world’s forests aflame. After the initial collision, debris would rain down everywhere, destroying even those buildings, wildlife, and people who were far from the impact. Virtually all living things inhabiting the surface would be killed, and even sea creatures would die as the temperatures of the oceans reached the boiling point. Long after the impact, the atmosphere would be coated in a layer of ash that would circle the Earth for months or even years, plunging the planet into a “nuclear winter” after the initial fireball. About the only things that might survive—such as is believed to have happened 65 million years ago after the last such event—would be creatures that could burrow underground or hide deep inside caves.