Finding Michigan's 5-mile crater, other meteor targets

Matt Linke, planetarium manager at the Natural History Museum at the University of Michigan, explains the importance of discovering a meteor and what it tells us about the solar system.

Hidden far below corn fields, a scattering of homes and an RV campground, there's a 5-mile-wide meteor crater in rural, southwest Michigan.

A space rock longer than three football fields smashed into what today is Calvin Township (pop. 2,037), about 30 miles northeast of South Bend, Ind. It hit about 450 million years ago, long before humans or even dinosaurs.

If it struck today, millions of people would die. A massive firestorm, spreading from a fireball 18 times brighter than the sun, would erupt immediately from a blast so catastrophic, it's difficult to imagine. Earth's Northern Hemisphere would be clouded with ash and dust, perhaps for decades, said Randall Milstein, who discovered the crater.

"Everything for 1,000 cubic kilometers (240 cubic miles) is pretty much done," said Milstein, astronomer-in-residence for Oregon NASA Space Grant Consortium, who teaches astronomy at Oregon State University. "Blown over, shredded, burned."

He confirmed the Calvin crater's existence in 1987, when examining information from about 100 gas test wells that had been drilled. Micrometeorites were found in drilling samples taken from hundreds of feet underground. The crater fills only two paragraphs on Wikipedia. But today, such an impact would affect volumes of human history: Long after the millions of regional deaths, there would be famines, groundwater contamination, altered temperatures and effects on air quality across the world.

At about 8:15 p.m. Jan. 16, a much smaller (2 yards in diameter) meteor arrived with a bright, thunderous explosion over southeast Michigan. It appears to be the 12th instance of meteorites confirmed in Michigan records dating to 1883, according to The Meteoritical Society. The cosmic phenomenon of meteors made the Free Press front page several times through the 1800s-1900s, mesmerizing people with fiery entrances.

Yam-sized meteorite hits car

A father was doing backyard work with his sons a little after 5 p.m. on Sept. 1, 1997 in northeast Washtenaw County, when they heard a sound like distant thunder.

"A few moments later, they heard a whistling sound passing over head, followed by a boom and a crash. Thinking that a car had left the road in front of the house, they ran up the hill to the side yard opposite the garage," according to an article from the Meteoritical Society.

They didn't see a car, but when they entered the garage, it was a mess of plaster dust with shredded drywall and insulation. There was a hole in the ceiling and a dint on a red car. There was also a rock and two chips on the garage floor.

The father called Matthew Linke, who is planetarium director with the University of Michigan Museum of Natural History Planetarium in Ann Arbor.

"I get these calls all throughout the year," he said, adding that "9.99 times out of 10, it's just a rock."

This is one of two cases he's seen in which it was indeed a space rock. The scene at the home included a "perfect hole in the roof ... kind of like a cartoon's outline" after a character runs through a wall. Linke said it was about the size of an over-sized yam or baking potato. It went through the roof, hit one of the attic supports, bending it, cracking the seam in the drywall and pulling down insulation and unplugging the garage door opener.

"The entire roof of the car had a big, bowl-shaped dent covered in insulation and plaster dust," Linke said, adding that, on the driver's side, it appeared as if someone hit the roof with a hatchet.

He said the owner eventually sold the meteorite.

'Cannon-like rumble'

Michigan Gov. George Romney in 1966 witnessed a meteor over Michigan while aloft in a private plane about to land in the area near St. Clair, Mich.: "We thought we were under attack ... It really frightened us," he told the Free Press in a story published the next day, Sept. 18, 1966.

That meteor lit up metro Detroit like the early-morning sun, frightening thousands. Alleged meteorite finds included a rock on a farm near Sweester, Ind., and other fragments near Huntsville, Ontario, about 100 miles north of Toronto. Air traffic officials reported the meteor was seen from Bradford, Pa., to Des Moines.

In 1939, a "cannon-like rumble" followed the sighting of a ball of fire in the sky over Detroit, according to a report on July 12, 1939. That one was reported by thousands of Detroiters, as well as people as far as New York.

Read more: 

Michigan meteor: Here's everything we know

Meteors can go from pretty ... to pretty deadly

Telephone switchboards were "swamped" as people called newspaper offices and fire stations to report the 1939 meteor. While many "were convinced that they saw it land 'right beside the University of Detroit,' or 'slap-dash in the middle of Lake St. Clair,'" experts said those estimates could be far off.

In fact, bad estimates continue to occur: Some people searched for meteorites from the Jan. 16, 2018 meteor in eastern Macomb County, but NASA scientists found them to be dozens of miles away, in Livingston County.

"They may be traveling horizontally for miles and miles and miles," Linke said. "In the blink of an eye, it could be 10 miles downrange."

In a Jan. 14, 1934 Free Press article, an executive with Michigan Mutual Liability Co. in Detroit was featured for his collection of meteorites. These included one reported to have landed in Eaton County, near Ionia:

"On July 11, 1933, an elderly farm couple, chores and dinner finished, were sitting on their porch watching the sunset. Suddenly, they were startled to see, hurtling through the sky toward them, a flaming object which they described as looking as large as a harvest moon," according to the article.

The couple ran into the house "in terror, heard a deafening roar and waited for the world's end," according to the report. They came back out to discover what appeared to be a meteorite at the end of a long furrow, about 18 inches under the ground near the barn. The Detroit-based executive learned of this and wrote to the farmer asking to examine it.

"The rest of the story is told in a series of letters from a doctor. These tell of how the owner started to Ionia to ship the meteor to Detroit, how the dire predictions of the neighbors upset the man's mind to such an extent that when he arrived in Ionia, he was mentally unbalanced.

"'His condition was such that he had to be committed to a hospital,' the doctor wrote. 'After proper care, he recovered.'"

Watch for falling rocks

The power of larger meteors is mindblowing, measured on the levels of multiple, massive nuclear bombs.

A meteor like the one that caused the Calvin crater, which was about 312 yards long, would eject massive amounts of debris, Milstein said. Chunks averaging roughly 3 inches and traveling at supersonic-to-hypersonic speeds would blast through an area roughly 62 miles from the impact zone.

"The blast debris would shred everything exposed in its path in all directions," he said, with further devastation spreading throughout the region. "There was a movie called Armageddon. The only thing good in that film is when a piece of that asteroid strikes the city of Paris, and they do a pretty good job of what such a detonation would look like in that case. The rest of the movie was awful."

About 200 impact craters, including Calvin crater, have been identified on Earth, and about 4,000 are believed to be identifiable – even despite erosion and plate tectonics. They're not terribly uncommon: "Impact craters are the most common geomorphic landform in the universe," Milstein said.

There's an estimated 1 in 2,000 chance that a devastating, kilometer-sized (0.6 mile-sized) asteroid hits Earth in the next 50 years, he said. (A meteoroid is a piece of an asteroid that gets broken off, according to NASA, and a meteor is a meteoroid that enters Earth's atmosphere.)

NASA has a program that searches space for larger asteroids that come too close to Earth for comfort — the Center for Near-Earth Object Studies, at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Formed in the late 1990s, the center has identified more than 8,000 asteroids of 460 feet or larger in size that are worth keeping an eye on, because their orbits take them by Earth within 1.3 "astronomical units," a measurement equal to the mean distance of the Earth to the sun. Some 886 asteroids identified by the program are a kilometer — almost two-thirds of a mile — or more in size.

While the 2-yard-long meteor that arrived Jan. 16 over metro Detroit gripped people's attention across multiple states, most meteors are much smaller even than that one. They're observed in the night sky as shooting stars, burning farther up in the atmosphere. They tend to be about a millimeter in diameter and arrive at much higher speeds.

"These things fall all the time, everywhere," Linke said. "Someone once described us as living in a cosmic shooting gallery."

Note: In a previous version of this story Matt Linke's name was misspelled in the photo caption and video.

Free Press staff writer Keith Matheny contributed to this report.

© 2018 Detroit Free Press


JOIN THE CONVERSATION

To find out more about Facebook commenting please read the
Conversation Guidelines and FAQs

Leave a Comment