The diamond-ring effect, visible just before and after the moon com­pletely blocks the sun, as seen from Ken­tucky.
Timothy Dolch | Courtesy

Mil­lions of people across the country traveled to get a prime view of the solar eclipse as its path stretched across the con­ti­nental United States Aug. 21. In addition to the visual spec­tacle of the moon crossing in front of the sun, solar eclipses offer unique insight into solar activity and its effects on Earth.

Assistant Pro­fessor of Physics Timothy Dolch and two stu­dents, freshman Nathaniel Birzer and senior Daniel O’Dette, traveled to rural Ken­tucky to see the total eclipse, pho­to­graph it with an optical tele­scope, and con­tribute data for a NASA citizen science project called Radio JOVE using a radio tele­scope to monitor solar activity.

During the total solar eclipse, the sun’s out­ermost atmos­phere or corona, which is nor­mally over­powered by light from the sun’s pho­to­s­phere, is easily visible. Addi­tionally, as the moon covers dif­ferent parts of the sun, sci­en­tists are able to determine the location of solar activity.

“Because of the moon’s presence, you know where the emission is not coming from,” Dolch said. “Inter­est­ingly, people around the country doing this simul­ta­ne­ously see dif­ferent parts of the corona blocked off.”

Through the Radio JOVE project, these student obser­va­tions will help con­sol­idate data showing the sun’s activity and its impact on Earth. O’Dette helped con­struct the radio tele­scope and monitor solar activity as a part of his senior project. Over the semester, he will be ana­lyzing the signals recorded during the eclipse, writing about the obser­va­tions, and con­tinuing to work on the tele­scope, O’Dette said.

Part of this work will include sorting through the recorded radio waves from solar activity, which the radio tele­scope records as a sound file. O’Dette said the natural activity in the recording sounds like a rushing wave, while inter­ference from objects such as police scanners sound like beeps and trills. Once Earth-based inter­ference is iden­tified, the sound files will be con­verted to graphs and ana­lyzed, O’Dette said.

Though a partial eclipse was visible throughout North America, only a narrow band across the United States expe­ri­enced a total eclipse, in which the moon com­pletely obscured the sun. Birzer said totality lasted a little over two minutes where their equipment was set up, but time felt sped up during the eclipse.

“Cer­tainly during the entire event, time felt very weird,” Birzer said.

In addition to the visible corona, an eclipse causes other natural phe­nomena, Dolch said. Of par­ticular interest to physi­cists is the area of the atmos­phere with high amounts of charged par­ticles and elec­trons, the Earth’s ionos­phere, which changes in response to the tem­porary darkness. During the eclipse, the ionos­phere is tem­porarily shielded from the solar radi­ation that gives energy to the charged par­ticles, and as a result, the ionos­phere can behave unusually, Dolch said.

The group observed other eclipse-related phe­nomena as well.

“There’s a lot of subtle physics during the eclipse,” Dolch said. “Of course you hear crickets and cicadas come out in the middle of the day, you see all the nighttime lights turn on. We also caught an inter­esting phe­nomenon known as shadow bands. Just before totality or just after … you have all this light that’s coming from exactly the same direction going through the atmos­phere, and the density vari­a­tions in the atmos­phere cause inter­ference. The result is that you get these dark bands moving across any white surface.”

Dolch said he and O’Dette are just beginning to go through the obser­va­tions from the eclipse, and will con­tinue working to prepare the radio tele­scope for use in future projects.

Birzer said the group was able to enjoy the eclipse, despite scram­bling to set up their obser­vation equipment in the park and make some last-minute repairs to the tele­scopes.

“It was a bit of a scramble because we were also busy standing and watching and just for­getting what other things we were sup­posed to be doing,” Birzer said. “It was incredibly beau­tiful.”