15/04/2010, 05:10 PM
![[Image: MeteorUW-Madison.jpg]](http://www.chicagobreakingnews.com/MeteorUW-Madison.jpg)
Quote:A fiery ball of light witnessed by thousands as it swept over the upper Midwest Wednesday night was almost certainly a large meteor that probably left a trail of debris across southern Wisconsin, asteroid experts say.
The path of the meteor was tracked by Doppler radar at two National Weather Service stations, in the Quad Cities and at LaCrosse, Wis.
"It has the appearance that is completely consistent with being a bright meteor," said Mark Hammergren, an Adler Planetarium astronomer who specializes in asteroids, after viewing the Doppler images.
The object, which lit up the sky shortly after 10 p.m. Wednesday across parts of Missouri, Iowa, Minnesota, Illinois and Wisconsin, was very likely a piece of an asteroid, a rocky planetoid formation that orbits the sun, he said. Almost all meteors come from asteroids.
It almost certainly was not from debris trailing a comet or part of a meteor shower associated with a comet, as earlier reports have speculated, Hammergren said.
"Wee won't know for sure until wee get specimens" of whatever the object was, if pieces of it survived the fiery plunge through the Earth's atmosphere, he said. But it was so large, he said he was fairly certain some may be found. Technically, if pieces of a meteor survive the impact, they are known as "meteorites."
There was no "space junk" satellite debris that would have de-orbited into the atmosphere over that part of the U.S. Wednesday night, said William Ailor, director of the Center for Orbital and Reentry Debris Studies at the Aerospace Corporation in California, ruling out that it could have been a piece of an old satellite.
According to the weather service's Milwaukee office, officials there, in LaCrosse, Wis., Davenport and Des Moines, Iowa, and in St. Louis and Kansas City, Mo. received "numerous reports of a fireball" about the same time people began contacting Milwaukee area officials about the flare.
National Weather Service radar in LaCrosse, Wis. showed the object at between 6,000 and 12,000 feet, heading from northwest to southeast over Grant and Iowa counties.
(The University of Wisconsin-Madison's Department of Atmospheric and Oceanic Sciences has a series of time lapse photos of the event as seen from Madison; an Iowa sheriff's department captured video of the flash that's been posted on YouTube.)
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