Astronomers have been so horrified by press scares over asteroids that they are toning down the scale they use to rate the threat posed in an attempt to discourage journalists from covering potential collisions. The most prominent recent furore involved asteroid QQ47, which briefly had a one-in-a-million chance of crashing into our planet in 2014. Some astronomers even want the way asteroids are assessed to be completely overhauled. The Torino scale, developed in 1999 by Rick Binzel of the Massachusetts Institute of Technology, is used to inform the public about potential impacts. It rates an asteroid's threat on a scale...