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IU astronomers join scientific effort to study sun’s corona during 2024 solar eclipse

IU Bloomington is one of only three regional coordinating sites for Citizen CATE, a continent-spanning project to record the eclipse during totality

May 30, 2023

Indiana University Bloomington’s location on the path of totality of the April 8, 2024, solar eclipse has put IU researchers in an enviable position among members of the international astronomical research community.

A group shot of participants in the Citizen CATE project Citizen CATE team members gathered at Australia's Exmouth peninsula to test equipment during a solar eclipse visible over the continent on April 20. In the second row are IU professor John Carini, far left, and student Rachel Weir, second from right. Photo courtesy of Rachel Wer.

The campus’s location — as well as its reputation as a place where stellar astronomers study the birth and formation of stars — has led to its selection as one of only three coordinating sites that will capture a nearly hourlong continuous video of the sun during totality. The undertaking will require over 30 teams of astronomers with specialized equipment at strategic locations across the U.S.

The project, known as Citizen Continental-America Telescopic Eclipse, or Citizen CATE, aims to reveal the secrets of the sun’s corona. As the dim outermost edge of the sun’s atmosphere, the corona is hundreds of times hotter than the surface of the sun and 10 million times less dense. The project, led by the Southwest Research Institute, is funded by the National Science Foundation and NASA.

“There are parts of the corona that are very poorly understood because it’s so hard to study,” said John Carini, a professor in the IU Bloomington College of Arts and Sciences’ Department of Physics. “It literally can’t be seen most of the time, even with satellites, since it’s millions of times dimmer than the surface of the sun. There’s a lot of scientific value in the opportunity presented by an eclipse.”

The project’s observations will allow scientists to study the complexities of the sun’s corona, including its shape, how it changes over time and what causes it to reach temperatures of millions of degrees Fahrenheit. The observations will assist not only scientists who study the Earth’s sun, Carini said, but also scientists who study stars in general.

People sitting under tents with scientific equipment. Participants in Citizen CATE set up equipment to capture the solar eclipse in Australia on April 20. Photo courtesy of Rachel Weir.

Carini will co-lead regional coordination for the Midwest site of Citizen CATE, along with Catherine Pilachowski, IU Distinguished Professor and Daniel Kirkwood Chair of Astronomy in the College of Arts and Sciences’ Department of Astronomy.

The lead trainer for the Midwest site is Rachel Weir, an IU Bloomington alumna who graduated in spring 2023 with a bachelor’s degree in astronomy.

Weir is also the person behind IU’s involvement in the project. While working on a research project last year at the National Solar Observatory – hosted by the University of Colorado Boulder – she was assigned a roommate, Sarah Davis, who was working on Citizen CATE.

“Everyone was a bit jealous of her because she had the ‘fun project,’” Weir said. “We kind of hit it off and stayed in touch, and I eventually connected with her advisors on the project during a conference, after which I emailed them about becoming a telescope site for the eclipse. I wasn’t really thinking regional coordinators or lead trainers at the time.”

But it wasn’t long after that IU was named a regional coordinating site, and Weir its lead trainer. And then in April, Carini and Weir traveled to Australia to meet other members of the project, including primary investigator Amir Caspi and the leaders of the other two coordinating sites in Texas and Maine. They also learned to use the project’s specialized scientific equipment and software during the total solar eclipse passing over that continent on April 20. Images from this “trial run” will help the project’s leaders to refine their methods in preparation for the main event in 2024.

As the lead trainer for the Midwest site of Citizen CATE, Weir is responsible for teaching people how to use the equipment required to record the eclipse. She expects to lead on-site instruction in Bloomington as well as engage in some travel throughout the Midwest.

Citizen CATE researchers mark off the observation area during the solar eclipse in Australia. Photo courte... Citizen CATE researchers mark off the observation area during the solar eclipse in Australia. Photo courtesy of Rachel Weir.

Although some teams on the project may include other professional researchers and astronomers, Weir said much of the work will likely rely on people who are simply passionate about astronomy. In fact, she said a similar project organized during the 2017 solar eclipse over North America included multiple teams with members from local astronomy clubs, including high school students.

“There will be some locations along the path of totality that are extremely rural,” she said. “You have to recruit based on who’s available and interested at those locations.”

In the months leading up to the 2024 eclipse, Carini said that IU astronomers also hope to work closely with the IU Center for Rural Engagement — not only to identify potential “citizen scientists” to participate in Citizen CATE but also to raise general awareness and excitement.

Despite the eclipse lasting only a few minutes at any individual location along the path of totality, Carini said the next year will be flurry of activity for everyone on the project — all in the name of scientific observation and discovery.

“They’re really doing it right with this project,” he said. “Everyone who assists in the observation of the eclipse will get the opportunity to assist in the analysis, and everyone will be credited as coauthors on the scientific paper that results.

“They’re going to where the science is happening, and they’re working with the people who are where it’s happening.”


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