By Published: March 27, 2024

For nearly four-and-a-half minutes on April 8, a swath of land crossing Texas will become the place to be for professional and amateur astronomers alike in the United States.

In the early afternoon, pilgrims to the Lone Star State will watch as Earth’s moon passes in front of the sun, completely blocking its light. The event will mark the first total solar eclipse to move over the contiguous United States since 2017, and the last until 2044. From Texas, the eclipse will trace a path northeast through Arkansas into Maine. Colorado will only witness a partial eclipse, in which the moon covers a portion of the sun’s face.

Man and woman stand behind a telescope on a sunny day

Kevin Reardon and Sarah Bruce on an expedition to view a total solar eclipse from Australia in 2023. (Credit:John Williams)

Researchers from CU Boulder and the (NSO) will be among the masses of people traveling to the Dallas-Fort Worth area for the historic event. They’ll point a telescope at the eclipse to record observations of the sun’s outer atmosphere, or corona—gathering hints to explain the physics of this mysterious and scorching hot region of space. Five CU Boulder students will join the expedition, including Rosilio Roman, an undergraduate studying computer science.

“It’s definitely exciting,” Roman said. “I’m at a point in my education where I want to taste as much as I can of the science being done. This is the perfect opportunity for me to sit at meetings and to hear the science being talked about.”

In 2023, a smaller team from the university and the NSO, which is located on CU Boulder's East Campus, journeyed to the northwestern tip of Australia—the eclipse’s path was mostly over ocean, making the remote town of Exmouth one of the few places on Earth where people could view the event from land. The eclipse lasted 52 seconds. But for Sarah Bruce, a graduate student in the Department of Astrophysical and Planetary Sciences, it was a powerful experience. Until then, she had only seen a partial solar eclipse.

“I could feel the drop in temperature, and just seeing the darkness in the sky, it was a completely different experience,” Bruce said.

The 2024 longer eclipse will give the researchers a chance to record much more detailed data about the corona, added Kevin Reardon, adjoint professor of astrophysics at CU Boulder and scientist at the NSO. But he also sees the event as a chance to introduce a new generation of scientists to these astronomical events, which have drawn in curious minds for millennia.

“I went to my first eclipse as an undergraduate,” Reardon said. “I’m really excited to take these students down to both learn about how science works and to experience the magic of an eclipse. It’s never what you expect.”

Map of the continental United States with a gray stripe passing through it from Texas northeast into Maine.

Path of the 2024 total solar eclipse on April 8. (Credit:NASA's Scientific Visualization Studio)

Eclipse science

Gianna Cauzzi, a scientist from the NSO, knows all about that magic.

In 2017, she and several colleagues drove to Wyoming to view that year’s total eclipse from just outside the town of Glendo.

“The town was a few seconds ahead of us in terms of how the eclipse was moving,” Cauzzi said. “We were waiting for totality, and we heard the whole town roar. I said, ‘This is going to be pretty good.’”

Three people gather on a roof to assemble three telescopes. Mountains in the background

From left to right, Sang Lapinee, Carina McCartneyand Gianna Cauzzi prepare telescopes for the coming eclipse. (Credit: Kevin Reardon)

In a black and white photo, four men assemble a large telescope

Jack Evans and colleagues assemble a telescope on the CU Boulder campus in 1951. (Credt: NSO)

This year, she and fellow NSO scientist Sanjay Gosain will fly to Mazatlán, Mexico, to observe the eclipse roughly 30 minutes before it reaches Texas—and with better odds of clear skies. The Texas team will include Reardon, Bruce and Roman alongside Ryan French, a NSO scientist and Brinson Prize Postdoctoral Fellow at CU Boulder;Ayla Weitz, a graduate student in astrophysical and planetary sciences; and undergraduates Carina McCartney, studying aerospace engineering, andSang Lapinee, studying astronomy and geology.

Cauzzi explained that, for most of the year, the sun’s corona is all but invisible to scientists on the ground. During a total solar eclipse, however, the feature materializes in the sky as tendrils of white light escaping from around the sun.

The teams will take advantage of that momentary appearance to zoom in on particularly active regions around the edges of the sun. The researchers will record the visible spectrum of light coming from those regions, using the data to map out the heat in the corona—beginning from just above the sun’s surface and extending hundreds of thousands of miles into space. That, in turn, could give scientists new hints about how particles from the sun accelerate into space, forming the solar wind that moves through the solar system and envelopes Earth.

Footsteps of giants

Astronomers, however, won’t just be watching the eclipse from the path of totality. On the Hawaiian island of Maui, the National Science Foundation's, operated by NSO, will also collect precise measurements of the corona. And in a stroke of luck, two spacecraft, NASA’s and the European Space Agency’s , will train their instruments on the sun at the same time—an unprecedented campaign that will allow scientists to compare data from the ground to data from space.

Bruce, for her part, can’t wait to see her second total eclipse. This one, she noted, will be even more special because it will pass over her hometown near Dallas.

“My mom said she'd bring us snacks,” Bruce said.

She and her fellow students are set to join a long line of scientists who have turned to eclipses to gather insights about the sun. Reardon, for example, likes to share a photo taken in 1951. It shows High Altitude Observatory scientist and NSO director Jack Evans and his colleagues assembling a telescope in front of Baker Hall on the CU Boulder campus. The following year, the researchers brought their instrument to Khartoum, Sudan, where they witnessed a total solar eclipse like the one that will soon appear above Texas.

“I like to think about these scientists 75 or 175 years ago who traveled around the world to places like Sudan, India and Bolivia to observe eclipses,” Reardon said. “Some of the giants in the field have made these expeditions, and to kind of follow in their footsteps, to observe the same kind of events they saw, is really thrilling.”