ON FEBRUARY 15th DA14, an asteroid 45 metres across, will sail past the Earth at 7.8km a second (4.9 miles a second). At just 27,700km away, it is well within the range of communication satellites. It will be the closest encounter on record with an asteroid this big. In 1908 an asteroid estimated to be around 100 metres in diameter destroyed 2,000 km² of forest in Siberia. Thankfully, such events are rare. NASA has identified 9,600 “near-Earth objects” since 1995, but just 861 with a diameter of 1km or more. The greatest threat to Earth currently is the 130-metre wide 2009 FD; but it has just a 1-in-526 chance of hitting the planet, and not until March 29th 2185. More prosaic things are far more dangerous. According to data from America’s National Safety Council, 27 people died in 2008 in America from contact with dogs (a one in 11m chance of death). The chart below compares the odds of dying in any given year from choking, cycling, being struck by lightning or stung by a bee.