The good news is that none of us has anything to worry about.
I really don't know how asteroids travel through space or how scientists can predict that one will crash into the Earth, especially so far in advance. I learned in Earth Science last year, however, that most objects that come that close to Earth are destroyed by Earth's atmosphere/gravitational pull before they have time to do any damage. Correct me if I'm wrong - I always zoned out when the teacher was lecturing us.
Right or not, on the off chance that this does happen, it's 172 years from now. We'll all be long gone.