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UW Releases New Details Follow Spring Meteor Shower | News

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UW Releases New Details Follow Spring Meteor Shower
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The meteorite that lit up the skies over southwest Wisconsin last spring has been officially dubbed the "Mifflin Meteorite" because it landed near Mifflin Township, and several of its pieces are now part of the permanent collection of the University of Wisconsin-Madison Geology Museum.

While the new name reflects where the meteorite landed, scientific analyses are revealing where it came from. Noriko Kita, a meteorite expert at UW-Madison, led a team of researchers from UW-Madison, the Field Museum, the University of Chicago and the Smithsonian Institution that analyzed the chemical composition, oxygen isotope ratio and structure of the rock.

They classified the meteorite as an "ordinary chondrite subgroup L5" based on its composition and high degree of metamorphism, which indicate its origin from the interior of an asteroid formed 4.6 billion years ago.

"There are a lot of L chondrites that have been found on Earth, and it's thought that they all came from the same asteroid," said John Valley, a UW-Madison professor of geoscience.

About 470 million years ago, the Earth was pummeled with debris, all with the same chemical signature, he said. Though the activity tapered off over the next 10 million years, occasional meteorites still hit the Earth.

"The hypothesis is that there was a collision, probably in the asteroid belt, that a fairly good-sized asteroid broke up and threw debris into the inner solar system. A lot of it hit the Earth, but there are still bits and pieces of it orbiting as asteroids even today," Valley said. "We think that the Apr. 14 meteorite was one more stone from that breakup."

Eight pieces of the Mifflin Meteorite are currently on display in the UW Geology Museum. Five are on loan to the museum, four from local veterinarian Chris Pagel and one from an anonymous landowner. Three are now part of the museum's permanent collection, acquired with help from Shea Gorzelanczyk of Green Bay and the Friends of the Geology Museum.

The Mifflin fragments are part of an exhibit featuring six of the 14 meteorites known to have landed in Wisconsin.

The UW Geology Museum is free and open to the public 8:30 a.m. to 4:30 p.m.  Monday-Friday and 9 a.m. to 1 p.m. Saturday. The museum will be closed on Thursday, Nov. 25, and Friday, Nov. 26, but will resume normal hours on Saturday, Nov. 27.

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