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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.”

  • SatyendraBhandari

    I am interested in the following description.. Would like to know the details of any measurements or observations that noted the characteristics – width and spacing of bands, direction of their movements, duration of shadow band activity and timings etc. And aslo the exact location and coordinates of the observing site. Any images and data. Kindly contact me at space.scientist@gmail.com. Thanks

    Satyendra Bhandari

    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.”