Space & Innovation

A Plummeting Meteor Lit Up the Night Sky Over Michigan

NASA scientists estimate the space rock was traveling 28,000 miles per hour when it hit Earth’s atmosphere and exploded with a force of 10 tons of TNT, triggering a shock wave equivalent to a magnitude 2.0 earthquake.

Don’t panic: Despite producing a vivid fireball and a shock wave that showed up on seismographs, the refrigerator-sized chunk of space rock that plunged into Earth’s atmosphere Tuesday night over Michigan wasn’t likely to have posed any threat to people on the ground.

Bill Cooke, who leads NASA’s Meteoroid Environment Office, told Seeker the meteor was likely about six feet long and traveling about 28,000 miles per hour. It broke up shortly after 8:00pm about 20 miles over Michigan, northwest of Detroit, but the fireball was visible 120 miles away at a NASA monitoring station in Ohio, he said.

“We typically see about 10 events like this in North America per year,” Cooke said.

The hypersonic rock disintegrated with an explosive force comparable to 10 tons of TNT, Cooke said. That’s big enough to produce a shock wave that showed up on US Geological Survey reports as a magnitude 2.0 earthquake — but a far cry from the meteor that broke up over the Russian city of Chelyabinsk in 2013. That packed a punch comparable to 30 Hiroshima-size nuclear bombs, shattering windows across the city.

“This was a small event compared to Chelyabinsk,” he said.

A comparable event occurred over British Columbia in September. But since this one happened in prime time over a more populated area, Tuesday night’s occurrence was bound to gather more attention, said Mike Hankey, operations manager for the American Meteor Society, which has been tracking cosmic interlopers since 1911.

“The most notable thing is the force of the sonic boom people felt. That’s what really got people all riled up about it,” Hankey told Seeker. Nearly 400 people had sent reports into the society’s website by Wednesday afternoon.

“These things do happen, but they’re rare enough for us in this time and place,” he said. “Most people will only see one of these events in their lifetime, and they only last for a few seconds.”

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The meteor was most likely a fragment of a larger asteroid, Hankey said, and it’s likely to have scattered small pieces of itself across the Michigan countryside. Cooke said those meteorites are likely to be a few ounces, looking vaguely like charcoal, and wouldn’t leave telltale signs like a smoking crater.

“Rocks this small are broken apart by the atmosphere, so they pose a vanishingly small risk to people on the ground,” Cooke said. NASA doesn’t look for objects as small as the one that plunged to Earth and probably wouldn’t have been able to spot a small, dark-colored object in advance, he said.