More of this Feature • Part 1: Introducing Asteroid 2001PM9

Related Stories • Thank God It's Doomsday!

From Other Guides • Impacts and Craters • The Hit of the Century • Measuring the Unimaginable

Elsewhere on the Web • Asteroid 2001PM9 Data • One Asteroid Could Ruin Your Day • Chicken Little: A Fable

Without a doubt, the existence of sizable near-earth objects hurtling through the cosmos poses a threat to life on earth. According to the most recent estimates, there are between 500 and 1,000 potentially hazardous lumps of space matter out there, and only 20 percent of those have been identified. That's a scary thought.

While the very biggest "doomsday asteroids" only strike the planet once every 100,000 years or so, scientists say, the odds are 1 in 3 that a smaller object with plenty of destructive potential will collide with earth some time this century — an even scarier thought.

We can take some small comfort in the fact that international teams of astronomers are working at a frenzied pace to identify and track the orbit of every one of these objects within the next decade. Currently there are no known asteroids of appreciable size on a collision course with earth, but that could change at any moment with new data. Despite the lack of imminent danger, we shouldn't rest too easy until our governments develop concrete plans to cope with the threat.

On the other hand, alarmism and rumormongering are counter-productive. If and when a truly threatening situation develops, we ought to look to credible scientific sources for information, not the Chicken Littles of the Internet. Case in point: the inaccurate and overblown rumor now circulating about Asteroid 2001PM9.

I contacted Dr. David Rabinowitz, a research associate in the physics department at Yale and one of the scientists in the forefront of NEO study, to get his expert opinion on the subject. His generous assessment of the email warning was that it must have been based on outdated calculations. According to the most recent data, he said, 2001PM9's closest approach to the earth in 2003 is expected to be .1 AU (AU = Astronomical Units, or the mean distance between the earth and the sun) and in 2005 will be .059 AU — missing us by millions of miles in both cases.  No impact is predicted.

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Sources and further reading:

• "Asteroid 2001PM9." NEODyS Object List.
• "One Asteroid Can Ruin Your Whole Day." Wired News, 14 Dec 2001.
• Chapman, Clark R., et al. "The Comet/Asteroid Impact Hazard: A Systems Approach." Southwest Research Institute Dept. of Space Studies, 24 Feb 2001.
• "Chicken Little." A fable.
• "Near-Earth Objects." Jet Propulsion Laboratory.
• "Spacewatch Scans the Heavens for Killer Rocks." Space.com, 17 July 2000.
• "Yale Researcher Finds Number of 'Near-Earth Asteroids' Are Fewer Than Believed." Yale press release, 12 January 2001.