The British agency responsible for identifying potentially hazardous asteroids says US astronomers are warning of a possible collision in 2014. The UK Government's Near Earth Object Centre says American astronomers have discovered a large, fast-approaching asteroid that could hit the earth on 21 March, 2014. But they add the chances of it doing so are just 1 in 909,000. What is more, any risk of an impact is likely to decrease as further data is gathered, they say. Credible threat The BBC's science correspondent Christine McGourty says that, although the chances this asteroid will hit the Earth are slim, it...