CHICAGO — A fiery ball of light witnessed by thousands as it swept over the upper Midwest on 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.
"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. CDT 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.
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.
"We won't know for sure until we 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.
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 Corp. in California, ruling out that it could have been a piece of an old satellite.