SIGHTINGS



Scale For Asteroid Threats
www.discovery.com
7-27-99



 
 
The asteroid that astronomers first said in March last year may strike Earth in 40 years would have initially rated a 1 on a new 0-to-10 scale of impact risks.
 
The "Torino Scale," developed by Massachusetts Institute of Technology astronomer Richard Binzel, was unveiled Thursday by the International Astronomical Union, according to The Boston Globe.
 
The scale was first presented last month at an astronomers' meeting on the risk of impacts from comets or asteroids held in Torino, Italy, where it was endorsed by astronomers, the Globe reports.
 
Binzel and other astronomers think many people were unduly and unnecessarily alarmed by some of the initial media reports of the possibility of an impact with that asteroid.
 
Despite the initial fright, on the new scale, asteroid 1997 XF 11 would have quickly been found to have a true risk of zero.
 
"What I hope the scale will accomplish is to put in perspective whether an object merits concern," Binzel says.
 
Binzel and others liken the new scale to the Richter scale, used for measuring the intensity of earthquakes. But the Torino scale is actually quite different. While those scales measure intensity, the asteroid scale attempts to combine both the severity of an impact and the probability of its occurrence, the Globe says.
 
For example, an object about the size of a house or smaller would be rated zero, even if it were certain to strike, because it wouldn't hurt anything. But an object headed for Earth that was, say, between 60 and 300 feet across would have a rating of 8, because such an impact could devastate a city-size region.
 
Objects larger than 3,000 feet across -- big enough to threaten the entire planet -- would get the highest rating of 10.
 
While praising the scale in general, Benny Peiser, an anthropologist at Liverpool John Moore University in England who circulates a daily newsletter of information about the hazards from asteroids and comets, tells the Globe, "As we've seen in the last 12 months, things change so rapidly and so unexpectedly that we might see some limitations of the scale."





SIGHTINGS HOMEPAGE