Image: Apophis
This graphic shows the orbit of the asteroid Apophis in relation to the paths of Earth and other planets in the inner solar system. staff and news service reports
updated 10/7/2009 6:41:11 PM ET 2009-10-07T22:41:11

The chances that a 885-foot (270-meter) asteroid might hit Earth in 2036 have been downgraded in light of updated information, researchers announced Wednesday.

The asteroid, named Apophis, first came to light in 2004 when scientists said it might have as much as a 1-in-40 chance of hitting Earth in 2029. They soon ruled out that possibility, but determined that 2029's close approach could set the stage for a collision seven years later on April 13, 2036.

For the 2036 collision, the chances were initially set at 1-in-45,000. Now scientists have used additional data about the space rock's orbit to downgrade the threat to no more than 1-in-250,000. Even more observations could push that probability down to zero.

Most of the updated readings came from previously unreleased images of the night sky that were captured by the University of Hawaii's 88-inch (2.2-meter) telescope on the summit of the Mauna Kea volcano. Astronomers used those readings, as well as measurements from the Steward Observatory in Arizona and the Arecibo Observatory in Puerto Rico, to recalculate the orbit.

“Our new orbit solution shows that Apophis will miss Earth’s surface in 2036 by a scant 20,270 miles (32,430 kilometers), give or take 125 miles (200 kilometers),” David Tholen, an asteroid hunter at the University of Hawaii, said in a news release. “That’s slightly closer to Earth than most of our communications and weather satellites.”

In addition to the 2029 and 2036 events, scientists identified another close encounter in 2068, with the chance of impact currently set at roughly three in a million.

The new risk assessment is to be presented Thursday in Puerto Rico at a meeting of the American Astronomical Society's Division for Planetary Sciences. Most asteroid risk assessments decline toward zero as more observations are factored in, and space scientists expect this to be the case with Apophis as well.

"The refined orbital determination further reinforces that Apophis is an asteroid we can look to as an opportunity for exciting science and not something that should be feared," Don Yeomans, manager of the Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a written statement.

This report includes information from The Associated Press and

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