Astronomers have changed the controversial Torino Scale, which categorizes the danger of an asteroid hitting Earth, to avoid needlessly scaring the public.
The new scale still ranks the danger level from 0 to 10, with 10 representing certain global catastrophe. The key change is to the description of lower-ranking threats.
In the original scale, adopted in 1999 by the International Astronomical Union at a meeting in Torino, Italy, collision threats from 2 to 4 were described as “meriting concern.”
“The idea was to create a simple system conveying clear, consistent information” about asteroids or comets that appeared to be heading for Earth, said Richard Binzel, a professor at the Massachusetts Institute of Technology who created the scale. But even that modest wording has at times sparked more public alarm than astronomers expected.
The revised scale says that so-called near-Earth objects with rankings from 2 to 4 should merit “attention by astronomers,” but not necessarily the public. The revisions also include language emphasizing that detailed study of a newly found object will almost always reduce the threat level to 0, meaning no danger.