Back in November 2005, NASA estimated, that Apophis (previously known as 2004 MN4), had a 1 in 5500 chance of hitting Earth in 2036.
No, not Apophis, the Goa'uld System Lord, but the killer asteroid (pictured below).
Well, it turns out that NASA miscalculated...
German Schoolboy, 13, Corrects NASA's Asteroid Figures: Paper
Turns out the odds of Apophis, the killer asteroid hitting Earth in 2036 are closer to 1 in 450!!!!
I've read reports of the odds being 1 in 45,000, then 1 in 5500, and now 1 in 450. I'm wondering if the highly paid brains at NASA know how to keep track of their zeros.