According to the Mayan calendar, the world goes kaput this December 21. You could prepare, but what's there to do--pack a suitcase? Researchers at Washington University in St. Louis have a better idea: They plotted our demise out, with science. After studying Earth-like exoplanets, which orbit closer to their stars than Earth does the Sun, the team explored what would happen to Earth's chemical composition were the planet to begin drifting toward the Sun. The result is a big, steaming bummer.