In the near feature, 15th February 2013 to be exact, an asteroid will pass by Earth at a record distance. Its designation is 2012 DA14 and it was first observed last year on the same month. It is 45m in size and has a mass of around 130,000 tonnes( as a comparison, a blue whale is about 30m and weighs 170t).
According to NASA’s site, it will come as close as 34,100 km, at a speed of 7.8 km/s(~28000 km/h). While this may seem very close in astronomical terms, as far as I read on this subject, there isn’t a risk of it colliding with Earth. For a better way to visualize just how far from the surface this is, imagine that the International Space station orbits at an altitude of 330-410 km, which is around the middle of the thermosphere, an outer layer of the atmosphere where the density of the “air” is so low that particles can travel up to 1km to hit another. The exosphere starts at around 800km. Still, relative to the distance from Earth to the Moon( which varies from 356,400 km to 406,700km), this is quite a close approach.
The main risk is of hitting space junk, or worse, functional satellites. In any case, this thing will at most provide a good show for amateur astronomers, as it won’t be visible with the naked eye(read more here).