spacetoday.net: Asteroid impact risk scale revised

Posted: Mon, Apr 18, 2005, 1:51 PM ET (1751 GMT)
Asteroid impact illustration (Don Davis/NASA)

Scientists announced last week that they have revised a scale commonly used to communicate the impact risks of asteroids in order to more accurately convey those risks to the public. For the last several years many planetary scientists have been using the Torino Scale, a system designed to distill a particular asteroid's risk of colliding with the Earth and the effects of such an impact to a number between zero (effectively no chance of collision) to ten (certain global catastrophe). The changes "better describes the attention or response" required at each level of the scale, in some cases redirecting concern from the general public to the scientific community. The revised scale also notes that an object's Torino Scale rank almost always goes down to zero over time as new observations allow astronomers to refine the orbit of the asteroid. The effectiveness of the scale in communicating risk as been a point of contention among some scientists, who believe even the revised scale is less than effective at communicating risk to laypeople.