"The chance of a similar impact is about 1 in 500 each year (Nature, vol 453, p 1178). Put another way, that's a 10 per cent chance of an impact in the next 50 years."Maybe I'm an idiot, but that seems like bad math to me. It's a 1 in 500 chance each year, and the previous year should have absolutely no relevance to the next. It's not like the asteroids are saying, "*****, we missed em last year, gotta make a better effort this year!" So it would be a .2% chance no matter what timeline we're using. Then again, I was never good at statistics, so I may be wrong.