NASA has confirmed that the fireball that streaked across the Midwestern sky early Wednesday was a satellite.
"There are many accounts from the midwestern states of a bright long-lasting fireball seen around 12:43 a.m. EDT last evening ... This event was not caused by a natural object; it was produced by the reentry and fragmentation of a satellite over that area of the country," the agency said in a Facebook post on its NASA Meteor Watch page.
At least one expert speculated that it was a failed Russian spy satellite.
A Harvard astrophysicist said he is "100% confident" it was, but doubts official confirmation of its origin will come.
Speculation began after the New York-based American Meteor Society received 81 reports of an eruption of green, yellow, red and white lights over the sky from witnesses including in Michigan; Illinois; Indiana; Kentucky; Ohio; and Ontario, Canada. The event was recorded at 12:43 a.m. by the AMS.
The AMS collects and displays eyewitness accounts of meteors and fireballs and promotes "research activities of both amateur and professional astronomers who are interested in meteoric astronomy," according to its website.
Some viewers recorded their sightings on the society's website, with some commenting that they believed it was a comet and others referring to it as a meteorite or a fireball.
Though initially reported as a fireball by the AMS, the organization concluded that it was likely "the re-entry of an unknown satellite or spent rocket body."
Jonathan McDowell, an astrophysicist at Harvard-Smithsonian Center for Astrophysics, claims the object is a Russian spy satellite, Kosmos-2551, that had a failed launch on Sept. 9 and had been orbiting the Earth ever since.
"We knew that it was going to re-enter sometime in the past 24 hours, a few days ago," said McDowell of the satellite.
Spotters were effusive.
"The most impressive meteorite I have ever witnessed," said Nathan V of Grand Rapids on the AMS website. "Spectacular!"
In Traverse City, Matt E said on the AMS site that it was a "world changing event," while Wendy S near Onsted thought it was both "wow and scary." Some said they heard the object make a sound; others focused on a thick tail of smoke that trailed it.
McDowell said Kosmos-2551 had been going around the world 17 times a day since its launch, with its speed decreasing after every rotation due to friction with the atmosphere.
When McDowell saw reports Wednesday morning that people in Michigan saw what he described as "clearly space debris," he checked the satellite's orbit and he said it became the obvious conclusion to him.
What distinguishes space debris from objects like fireballs, meteors or space rocks, said McDowell, is the speed at which they travel.
At a "mere 17,000 miles an hour," objects like what he said is Kosmos-2551 are going much slower than something like a shooting star, and take a relatively long time to break up.
McDowell added that some of the colors witnesses described seeing can be attributed to different materials like metals on a satellite melting or burning up as the satellite descends.
"It was exactly the right time in the right place during the re-entry window that we were expecting it to break up," he said, referring to the 12:43 a.m. time stamp.
The astrophysicist relied on tracking data from a website, space-track.org, that uses radar to track objects in space and makes much of that information available to people, but an account is required in order to "check that you're not like a North Korean spy," McDowell said.
He said it is unlikely for an agency like the United States Space Force to confirm that the object was Kosmos-2551, but what usually follows is an update with a particular time and specific latitude or longitude, and to him that would be a solid enough assurance.
The Space Force, which monitors space activity around the world, did not immediately respond to a request for comment.
McDowell added that this type of incident is not uncommon.
"This is something that happens every few months," he said. "Somewhere in the world, there's a satellite re-entry, and it's fairly easy to identify. But for any one area, it's an unusual thing, and so people freak out."