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Bruce BettsOctober 7, 2009

Apophis is less scary than it used to be

Based on analyses of previously unstudied telescopic data, NASA scientists have released new predictions for the path of the 300-meter-diameter asteroid Apophis. Because they were able to better define Apophis' orbit, scientists were able to calculate a reduced likelihood of impact with Earth in 2036. The probability of impact went from 1-in-45,000 to 1-in-250,000.

Apophis will be visible to the naked eye to some portions of the Earth in 2029 when it comes closer to Earth's surface than our geostationary satellites.

Steve Chesley and Paul Chodas at NASA's Jet Propulsion Laboratory used data taken by Dave Tholen and collaborators at the University of Hawaii's Institute for Astronomy in Manoa on 40 nights between 2004 and 2008. The observations were made at the University of Hawaii's 88-inch telescope, located near the summit of Mauna Kea. They also incorporated other data sets.

Apophis is still of scientific interest, and though its probability of impact has gotten extremely small, it still represents a reminder that these objects are out there, and we should carefully track them to help prevent the only preventable natural disaster.

The Planetary Society held a $50,000 Apophis Mission Design Competition that challenged teams to design "tagging" missions to refine Apophis' orbit. Apophis was used as a concrete example for design purposes, but represented trying to do this with any potentially threatening asteroid. Planetary Society Shoemaker Near-Earth Object Grant winner Roy Tucker was a co-discoverer of Apophis.

Read more: Earth impact hazard, asteroids, Earth, Planetary Society People, Shoemaker NEO Grants

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Bruce Betts

Director of Science and Technology / LightSail Program Manager for The Planetary Society
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