Word: asteroidal
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Then suddenly, the danger was gone. Barely a day later, new data and new calculations showed that the asteroid, dubbed 1997 XF11, presented no threat at all. It would miss Earth by 600,000 miles--closer than any previously observed asteroid of that size but a comfortable distance. Still, the incident focused attention once and for all on the largely ignored danger that asteroids and comets pose to life on Earth. As Los Alamos senior scientist Greg Canavan put it, paraphrasing Dr. Samuel Johnson, "Nothing so clears the mind as the sight of the gallows...
XF11 was discovered last Dec. 6 by astronomer Jim Scotti , a member of the University of Arizona's Spacewatch group, which scans the skies for undiscovered comets and asteroids. Using a 77-year-old telescope equipped with an electronic camera, he had recorded three sets of images, 30 min. apart, of a small sector of the night sky. The digitized images, fed into a computer programmed to look for objects moving against the background of fixed stars, revealed an asteroid that Scotti, in an E-mail to Marsden, described as standing out "like a sore thumb...
...brief but exciting 24 hours, the big asteroid commanded everyone's attention. Astronomer Hills calculated that an asteroid the size of XF11 colliding with Earth at more than 38,000 m.p.h. would explode with the energy of 300,000 megatons--nearly 20 million times the force of the bomb that leveled Hiroshima. If it hit in the ocean, he predicted, it would cause a tsunami (commonly called a tidal wave) hundreds of feet high, flooding the coastlines of surrounding continents. "Where cities stood," he said, "there would be only mudflats." A land hit, he calculated, would blast out a crater...
Gehrels heads Spacewatch, Scotti's astronomy group and one of two such teams dedicated exclusively to the discovery of threatening "near-Earth objects" (NEOs). The other group, called NEAT (for near-Earth asteroid tracking), is run by Helin and uses an Air Force telescope atop a mountain on Maui, Hawaii...
Strapped for funds--NASA contributes only $1.8 million annually to asteroid hunting--astronomers fear it will take decades to discover most of the larger objects. With only a few million more dollars a year, they say, and with access to the other two Air Force satellite-tracking telescopes, most of the kilometer-wide and larger asteroids could be identified and tracked within 10 years...