There is a small but significant chance that an asteroid will strike Earth in 2030 with a force up to 100 times the Hiroshima bomb, an international team of astronomers concluded Friday.
The International Astronomical Union and space scientists at NASA's Jet Propulsion Laboratory said there is a 1-in-500 chance that a newly discovered asteroid-like object called 2000 SG344 will hit Earth on Sept. 21, 2030. The object could be anything from a discarded rocket booster to a sizable asteroid.
The announcement, posted on the Internet by the International Astronomical Union, is the first formal public prediction of a potential collision with a piece of the cosmic debris that litters the solar system.
The warning arises from a special astronomical review process designed after a false alarm two years ago to eliminate premature predictions of celestial calamities.
On a newly devised 10-point scale for grading potential impact hazards, the object is just at the threshold of concern. It was given the lowest rating of 1 because of its relatively small size and the uncertain odds. The rating means the object merits careful monitoring.
The object was discovered trailing in Earth's orbit around the sun by astronomers using the 3.6-meter Canada-France-Hawaii telescope on the island of Hawaii. The probability that it might hit Earth in 2030 was first determined earlier this week by JPL researcher Paul Chodas. It was then verified over the last 72 hours by technical reviewers in Italy, Finland and the United States, organized by the International Astronomical Union.
"This is a first for us," said space scientist David Morrison at NASA's Ames Research Center, who is chairman of the Astronomical Union's working group on such collision hazards. "We have never before had a prediction at this high level of probability. In the past we have talked about 1 in 10,000 or 1 in a million."
In making their concerns public Friday, the astronomers walked a delicate line between prudent secrecy and public disclosure, weighing a chance of ridicule against their demands of public responsibility.
Two years ago, asteroid watchers at the Minor Planets Center in Cambridge, Mass., triggered worldwide alarm by announcing--and then almost immediately retracting--news that a mile-wide asteroid called XF-11 might hit Earth in 2028.
