According to Robert Lunsford of the American Meteor Society (AMS), reports of a fireball came from across the state Thursday evening.
"The sightings were clustered right around Chicago," Lunsford said. "We've only received a couple from the St. Louis area. We have 34 total sightings. St. Louis seems to be on the southwestern edge of our reports. It was apparently seen as far away as Ann Arbor, Michigan."
Lunsford added that similar sightings came from Texas and Louisiana around 2 a.m. Friday. He said the southern fireball had about half as many reports as the one over Illinois. Such bright fireballs are common in February, March and April, he added.
"This is the peak time for evening fireballs," he said. "I have no doubt that it was a meteor."
Lunsford said most of the reports claimed to have seen a large green fireball, but some were blue or yellow. According to Lunsford, the seemingly strange colors are actually quite common when a large chunk of space debris enters Earth's atmosphere.
"Entering the atmosphere excites the oxygen molecules and creates a sort of greenish glow," he said.
The AMS is still investigating the case, which includes looking for evidence that the meteor metamorphosed into a meteorite by hitting the surface of Earth.
Comment: Interestingly, on the same date a fireball was seen over the UK: Fireball meteor captured on camera over York, UK