writes "NASA and the Jet Propulsion Laboratory have released a simulation of the path of an asteroid, named Apophis, that will come closest to Earth, since humans have monitored for such heavenly bodies. The asteroid, which once held an above 2% chance of impacting Earth, had caused a bit of a scare when it was first announced that it would enter Earth's neighborhood some 30 years in the future.
However since that announcement in 2004, more recent calculations have put the number at 1 in 250'000. The simulation can viewed here."Link to Original Source