ST. LOUIS — By 9 p.m. Monday night the videos were already spreading online: a meteor streaking through the sky behind the Gateway Arch. The same fireball caught on security cameras blazing over suburban homes. A sonic boom heard for miles.
By the next morning, a team of NASA experts had the answers on what that meteor, aka “Event: 20191112-025148,” turned out to be.
What thousands saw about 8:51 p.m. Monday was a basketball-size hunk of rock that broke off an asteroid belt between Mars and Jupiter before entering Earth’s atmosphere as a meteor, Bill Cooke, of the NASA Meteoroid Environments Office in Huntsville, Alabama, said Tuesday.
NASA experts used hundreds of eyewitness accounts from as far away as South Dakota and Minnesota along with two videos to calculate surprisingly precise details about the meteor: The approximately 220-pound rock traveled through the sky at 33,500 mph, faster than the speed of sound, causing the sonic boom. A NASA weather satellite helped the agency confirm it was brighter than Venus in the sky, making it a fireball.
Two videos, a standing shot of the Gateway Arch and another taken at the Missouri Skies observatory in Albany, Missouri, helped the NASA team track the meteor’s trajectory and path. It first appeared at an altitude of 59 miles above the town of Cedar Hill, southwest of St. Louis in Jefferson County, and continued for about 70 miles before breaking into pieces 12 miles above the ground, Cooke said.
It is possible some pieces of the meteor fell to the ground, creating rocks called meteorite, Cooke said. But that might not look how you would expect.
“It’s not like the movies,” said Cooke, who spends most of his time helping NASA missions avoid meteor risk. “Meteorites are not flaming rocks of doom. By the time a meteorite hits the ground, it’s completely cold.”
Meteorites also don’t typically make craters like the movies show, and are perfectly safe to pick up, Cooke added.
“This isn’t Superman, and meteorites are not kryptonite,” he said. They look a bit like coal because the outside melts into a black outer layer called a fusion crust.
Finding meteorite is rare, only about 24 confirmed meteorites have been found in Missouri since 1839, according to a website maintained by Randy Korotev, a meteorite researcher who recently retired from Washington University.
While meteorites are few and far between, meteors themselves are common, said Erika Gibb, chairwoman of the Department of Physics and Astronomy at the University of Missouri-St. Louis.
“If you go out on any given clear night you can see several meteors in an hour. There are all kinds of debris in our solar system and we’re getting hit by small stuff on a regular basis,” Gibb said Tuesday. “Most just aren’t very big and bright like the one last night.”
A typical meteor might only be the size of a pebble and burn up long before hitting the ground, Gibb said.
Will Snyder, manager of the McDonnell Planetarium at the St. Louis Science Center, said he hopes the fireball Monday will get people interested in keeping an eye on the night sky.
“It gets people looking up and curious about what they’re seeing,” Snyder said, adding that more prime meteor-spotting times are coming up.
The Alpha Monocerotids meteor shower is expected to have an outburst of meteors about 10:30 p.m. Nov. 21.
The Geminids meteor shower is expected to peak about 8 p.m. Dec. 13.