There is an asteroid called 2011 AG5, and if it follows the orbit scientists have plotted for it so far, there is a small, small chance that it could hit Earth in February 2040.

Don't quit your job and sell your house just yet. Astronomers, who have been tracking the asteroid since January 2011, say it is in an elliptical orbit that could bring it somewhere near Earth in 2040. Earth is about 8,000 miles in diameter; the asteroid appears to be about 450 feet across.

The problem is that having watched it for only about half an orbit around the Sun, the scientists cannot say for certain where it will be 28 years from now. So, for the moment, NASA's Near Earth Object Program says the odds are about one in 625 that it could hit us in that still-distant future.