Back in December 2004, the asteroid 99942 Apophis briefly made the news before the Asian Tsunami crested. At the time, is was speculated that the asteroid would pass exceedingly close to Earth in 2029, with a high probability of impact. Further orbital studies drastically reduced the chances of a strike and the story faded from view.
Well hold those horses. Turns out it 99942 Apophis is still a threat. The encounter in 2029 will “>alter the orbit of the asteroid, increasing the chances of a catastrophic encounter with our planet in 2036 to 1 in 10,000. NASA is looking at placing a radio beacon on the asteroid by 2013 to precisely track its orbit.