You know the drill on this one: The ancient Mayans used several intricate calendars to number their days, and their Long Count Calendar's 1,872,000-day Great Cycle will wrap up on Dec. 21, 2012.
Of course, as far as we know, the Mayans never said anything about the world ending in 2012. If anything, the close of the Great Cycle would just be an excuse to throw a massive party. And the next morning? You guessed it: Time to crack open a new calendar and get on with your life.
Still, apocalypse-mongers like to assume the Mayans possessed some astrological insight into Earth's future. They argue that a world-ending planetary alignment will occur on Dec. 21, 2012, but every astronomer on Earth can tell you this isn't even remotely in the cards. Repeat: Credible scientists are not worried about any of this.
How to Prepare: Just to be on the safe side, it pays to keep some clean water (at least one gallon or 4.54 liters per person per day) and nonperishable food items on hand in case of emergency, be it the end of the world or just a heavy snowstorm.
Up next, we'll take on the rapture.