The Great Michigan Fireball of January 2018

February 21, 2018

Longtime friend and colleague Todd Slisher has been an astronomy geek since his days growing up in the Grand Rapids area. He was an active student member of GRAAA prior to going on to college at the University of Michigan, and then a career as a museum/planetarium specialist. Todd is currently the executive director of the Sloan Museum and Longway Planetarium in Flint. On Tuesday evening, January 16th, Slisher was in his home near Brighton watching “Jurassic Park” on his basement theater system with his twin 9 year old sons when his phone started going crazy.

 

Messages all had the same theme. Was he aware of the "fireball"? Had he seen the "flash in the sky" Had he heard the explosive breakup? Facebook and Twitter were abuzz. With the theater sound cranked up and thundering footfalls of prehistoric creatures coming through the subwoofer, he and the boys had been oblivious to what was going on almost over their heads.

 

Fortunate observers, dash cameras, and surveillance devices throughout the lower peninsula of Michigan and in surrounding states and provinces had captured a large falling meteor (commonly called a fireball or bolide) and its intense explosive breakup just after 8pm that Tuesday evening.

 

In the Grand Rapids area, where it was partly cloudy, some visual observers reported only a surprise flash, similar to lightning, though there were a few who actually saw the  fireball’s plunge. Video footage shows the bursting object coming almost straight down, and flaring out in just two to three seconds.

 

Video, visual sightings, and weather radar observations together provided evidence of a slowly falling object, a piece of space rock 6 feet or so in diameter. It violently broke apart and mostly burned up about 15 miles above the ground due to intense frictional stresses. A minor earthquake was registered in the Detroit area, and there were reports of sonic booms (shock waves produced by the plunge) from throughout southeast Michigan.

 

By early the next day, reports flooding in to Slisher and science colleagues clearly indicated that the projectile broke up over southeastern Michigan. Representatives of the American Meteor Society were on their way to the region, confirming that ground zero was somewhere near Detroit. If there was to be any chance of recovering fallen meteorites, a more precise determination of that ground zero would be required. Initial media stories were not consistent; some had an end point north of Detroit, and others near New Haven to its northwest.

 

Seeing online video of the event reminded Slisher that his former home near the village of New Hudson (just east of Brighton), which he was renting out, had operating security cameras. Using an online app, he logged on to see if they had recorded anything. The front camera caught a brilliantly lighted snowy landscape as the fireball flashed overhead right at 8:08pm. But it was the view captured by the rear entry camera that really caught Slisher’s attention. Bright light from the fireball cast a distinct shadow of the peak of the roof onto the snow-covered deck. The video clearly showed the shadow moving and elongating as the object fell, providing vivid points of reference in real time.

 

Slisher had the proverbial "aha" moment. “Go to the deck, mark where the shadow fell at the beginning and end of the brief event, and you are on your way to finding the fireball’s trajectory!” he excitedly thought.

 

Then he had another bright idea. Perhaps the camera’s audio recorder had caught the reverberation from the explosion. Sure enough, a faint sound was heard 104 seconds after the flash. Multiplying that interval by the speed of sound, he determined the meteor was about 21 miles distant when it exploded in the atmosphere.

 

All he needed to do was make arrangements to visit his former home, take a few measurements on the deck based on the video shadow, call upon his high school geometry (the good old Pythagorean Theorem) and apply some other basic calculations to come up with where the object met its demise.  The result: straight up from a point 14 miles due west of his former home. That would place the end point and breakup about 8 miles southwest of Brighton, along the border of Hamburg Township. It was time to go prospecting!

 

A day and a half after the fireball event (Thursday morning, January 18th), Slisher canceled appointments and rounded up a group for the hunt. They consisted of Longway Planetarium colleagues Buddy Stark and Brian Wolff, as well as Tony Licata and Sandra Macaki from the Farmington Community Stargazers, of which Slisher is a member. By mid-afternoon, the team was in the suspected "strewn field" as it is called by meteorite hunters, southwest of Brighten.

 

Tony Licata had brought along a metal detector, and the group optimistically packed ziplock bags and aluminum foil to preserve any finds. A local park turned up nothing, so attention turned to two-mile-wide Strawberry Lake, safely covered with plenty of ice and two inches of snow. The flat surface would be more promising than undulating terrain.

 

An hour of systematic back and forth searching across the lake proved fruitless. A lot more wondering followed as the sun sank toward the horizon on a bright clear winter day. Then Slisher spotted "something" dark, and partially covered with snow. Calling his colleagues over, he carefully tapped it out of the snow. It clearly exhibited the nearly-black charred crust characteristic of a fresh meteorite.

 

 

"This could be it!" Slisher exclaimed, realizing that this could be the first meteorite find of his long career. He carefully wrapped the roughly postage-stamp-sized specimen in protective foil and placed it in one of the ziplock bags. Documentary pictures were taken.

 

 

The search continued for another 45 minutes, when Tony Licata spotted a second dark object contrasting with the white snow. Spurred on by excitement of two finds and fading daylight, the hunt continued with added urgency. Just after 6pm, Brian Wolff came upon the third and largest specimen, roughly the size of a matchbox. This was the clincher. The burnt crust was stuck to the ice, and when the specimen broke loose, part of that crust broke off to reveal the cement gray interior typical of stony meteorites.

 

There could now be little doubt that these three tiny rocks were visitors to earth from very far away, perhaps as far as the asteroid belt.

 

As darkness fell, the tired, cold, but elated meteorite prospectors went to Licata’s cottage about 10 miles away to warm up and take a closer look at their precious finds.

 

From left to right: Slisher, Licata, and Wolff, each pointing to their personal find.

 

The specimen Slisher found was kept frozen and has since been forwarded to NASA. It is now at the Johnson Space Center in Houston for analysis. The largest is on display in the lobby of Longway Planetarium, and the third is making the rounds for group talks.

 

 

Robert Ward and Larry Atkins of the American Meteor Society, simultaneously searching in the same general area, also came up with specimens, and Licata is still prospecting as his time permits. There are likely more meteorites out there, hidden by snow but awaiting discovery once it melts.

 

 

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