According to numerous sources on the Internet, in 2012 a planet called Nibiru will collide with Earth, resulting in the extinction of the human race. Or the Earth's magnetic poles will flip, causing the rotation of the planet to reverse, resulting in the extinction of the human race. Or the Earth will fall into something called a "dark rift" in the Milky Way — resulting in the extinction of the human race.

So, what's NASA doing about it?