On the morning of Aug. 13, 2022, a loud boom was heard across the Salt Lake Valley. As it turned out, it was the sound of a falling meteorite that eventually landed in the salt flats west of Salt Lake City.
“I was just getting up, I was in my driveway, I heard a loud sonic boom and then some rumbling, kind of like thunder after that,” said Dr. James Karner, a research professor in the Department of Geology and Geophysics. “I actually thought that could be what a meteorite sounds like when it breaks through the atmosphere.”
Karner’s suspicions were confirmed when the ski resort Snowbasin released video footage of a fireball falling through the sky.
“The relative rarity of an event like this — the only other witnessed fall ever in Utah was in 1950,” Karner said. “Before this meteor hit, there had only been 26 meteorites ever found in Utah.”
The meteorite was found in the salt flats by a meteorite hunter from Nevada named Sonny Clary. Clary then agreed to donate a slice of the meteorite to the University of Utah in order to have it studied further, as well as named by The Meteoritical Society.
“If you’re the first finder of a meteorite, apparently, you’re very keen on getting your name in the archives,” Karner said. “In order to have a meteorite named, you have to have an institution classify it, just figure out what kind of meteorite it is and write up a little report then propose a name for it, so he agreed to let the University of Utah do that.”
Karner, as the U’s resident meteoriticist, is head of the team tasked with the analysis. “There’s not a lot of people that study meteorites here like at Arizona State or Portland State,” Karner said. “But [Clary] said, ‘I think, Utah, it’d be good for you to have this meteorite since it’s such a community event.’”
So, the process of analyzing and naming the meteorite began.
“The goal of meteoritics is to understand the origins of the solar system,” said Dr. Benjamin Bromley, professor of Physics and Astronomy. “These samples that people find are billions of years old, and many of them were formed as rocks at the beginning of the solar system, as all the solids came together.”
Bromley said the analysis of such samples could contain clues for how Earth and other planets in the solar system were formed.
“These are, in some sense, failed planets because they’re just little bits of debris,” he said. “They’re composed of pretty primordial stuff in many cases. So I think they’re really beautiful and really informative with the clues they have for understanding our solar system.”
The first step was to determine the composition of the sample. “Most meteorites are called stony meteorites, and they come from asteroids,” Karner said.
To explain this, he had a sample of another meteorite, separate from the one found in the salt flats, and pointed to little silver specks within the sample. “Those are little grains of iron-nickel metal. Those are unique to meteorites because all the iron has been oxidized on the surface of the Earth, but in space, you can get iron-nickel metal, and that tells you you have a meteorite.”
He explained the amount of metal in meteorites could vary from little specks in the stone to a meteorite that was an entire chunk of iron. The meteorite that fell in Utah is known as a high iron chondrite, meaning that, like most meteorites, it is a stony type that came from an asteroid, but with a high amount of iron in its composition.
Once the meteorite was classified, more information could be determined regarding its origin. Karner described how sometimes asteroids divert from their original orbits into elliptical ones, which pass much closer to Earth.
“Asteroids that have gotten knocked out of their regular circular orbit, and now they’re in this Earth-crossing orbit,” he said. “So sometimes we get lucky, we get pieces that break off that little sub-asteroid and come to Earth as meteorites.”
This origin is fairly common as far as meteorites go, but according to Bromley, the high iron quantity reveals something rare about the rock. He said because of the process in which asteroids are formed, known as differentiation, the metals in them sink to the center and the lighter materials rise to the top.
“So a heavy metal object like this undoubtedly didn’t come from the surface of some asteroid,” he said. “It likely came from a deeper impact that kind of ripped out the interior of something closer to the center of the object.”
The next step is getting the meteorite officially named by The Meteoritical Society. Karner’s proposed name is The Great Salt Lake Meteorite.
“Meteorites are named for usually the closest geographic place name,” Karner said. “I think Great Salt Lake would be cool since they found this near the Salt Lake, and there’s probably pieces that went into the Salt Lake.”
Aside from the science of it all, Karner also stressed how unique of an opportunity this is for the U and the broader community.
“There’s a lot of rock hounds in Utah, people that think they found meteorites, but they’re super rare,” he said. “More rare than diamonds and gold and anything you can think of. Even more rare than that is to see a fireball, hear the explosion and then find the rock that came with it.”
Bromley said he feels U students should care about and take a genuine interest in this science.
“This is studying our origins; this is studying where the Earth came from,” he said. “This is contributing to the body of knowledge for how habitable planets form and that’s extremely important towards understanding what other planets may be out around nearby stars.”
Even limited to Earth, Bromley believes this science has serious application and implications.
“It also speaks to the importance of our own planet and nurturing our planet,” he said. “I view this as a contribution to our own home, understanding it and caring for it.”