What We Learned So Far From The Total Solar Eclipse of 2017—And Why There's Much More to Come
Americans went mad for the total solar eclipse on August 21—and so did scientists. Earlier this month, researchers at the fall meeting of the American Geophysical Union in New Orleans teased out the first results of experiments performed during the eclipse.
"From a NASA perspective, there is no other single event that has informed so many scientific disciplines," Lika Guhathakurta, an astrophysicist at NASA Ames Research Center, said. Among the affected fields include solar dynamics, heliophysics, Earth science, astrobiology, and planetary science. "The eclipse provided an unprecedented opportunity for cross-disciplinary studies."
To that end, NASA grants and centers supported Sun-Moon-Earth alignment research during the eclipse that involved balloons, ground measurements, telescopes, planes that chased the eclipse, and a dozen spacecraft from the agency, as well as from the National Oceanic and Atmospheric Administration, the European Space Agency, and the Japanese Space Agency. In some regions, scientists meticulously mapped responses to the total eclipse by the land and the lower atmosphere. They measured ambient temperature, humidity, winds, and changes in carbon dioxide. These data were taken to find new insights into the celestial event, which occurs somewhere on the Earth every 18 months. (Calculate here how many you could potentially see in your lifetime.)
PEERING THROUGH THE "HOLE" IN THE IONOSPHERE
Of particular interest was how the eclipse affects the ionosphere, the barrier region between the atmosphere and what we think of as outer space; it is the altitude range where auroras occur, and where the International Space Station and low Earth orbit satellites are found. The ionosphere is affected by radiation from the Sun above and by weather systems below. The eclipse gave researchers the chance to study what happens to the ionosphere when solar radiation drops suddenly, as opposed to the gradual changes of the day-night cycle.
A total eclipse essentially creates a "hole" in the ionosphere. Greg Earle of Virginia Tech led a study on how radio waves would interact with the eclipse-altered ionosphere. Current models predicted that during the brief interval of the eclipse, the hole would cause waves to travel much farther and much faster than usual. The models, it turns out, are correct, and data collected during the eclipse supported their predictions. This facilitates a better understanding of what happens on non-eclipse days, and how variances in the ionosphere can affect signals used for navigation and communication.
FINDING UNEXPECTED INTERACTIONS
"NASA's solar eclipse coverage was the agency's most watched and most followed event on social media to date," said Guhathakurta, with over 4 billion engagements. That sort of frenzied public interest for what amounted to a 90-minute celestial event over a thin strip of the United States, with around two minutes of totality for any given area, allowed scientists to engage "citizen scientists" to help with data collection.
Matt Penn of the National Solar Observatory led the Citizen CATE project (Continental-America Telescopic Eclipse), which deployed 68 small, identical telescopes to amateur astronomers across the eclipse path. "At all times, at least one CATE telescope was in the shadow looking at the [Sun's] corona," Penn said. "And sometimes we had five telescopes looking at the corona simultaneously." This resulted in a lot of data. "We got 45,000 images, and to go along with that, we got 50,000 calibration images."
They're still working on the data processing, but by combining images similar to the way smartphone cameras create HDR images in certain lighting conditions, scientists are able to view the Sun's corona—the shimmering halo of plasma that surrounds it—in stunning new detail. Image-processing techniques on the high-resolution data yielded surprising results. Specifically: There are interactions between the "cold" atmosphere of the Sun—the chromosphere, which is "only" 10,000°F—and the hot corona, which is 1,000,000°F. "We're hoping to analyze these data in more detail and come up with some publications in the near future," Penn said. The project's telescopes remain in the hands of the public, and new experiments are underway.
"Most of our volunteers were going see the eclipse anyway, and what we did was try to enable them to elevate their experience by participating in research. And that goes from collecting the data to publication," Penn tells Mental Floss. "We could have had 200 sites easily with the amount of interest we had." The public's keen interest in the eclipse will spur experiments of commensurate ambition in 2024, when North America again experiences a total solar eclipse.
ATTEMPTING TO ANALYZE DATA NO ONE HAS EVER SEEN BEFORE
Penn's project wasn't the only science conducted with a public-engagement aspect. The Eclipse Ballooning Project, led by Angela Des Jardins of Montana State University, enabled 55 teams of college and high school students to fly weather balloons to above 100,000 feet. There, they took measurements to see how the eclipse affects the weather-influencing lower atmosphere. The balloons also live-streamed the eclipse as it occurred across the continent. To give a sense of how long the project has been in development: When it was conceived, live-streaming as we experience it today had not yet been invented.
She tells Mental Floss that the project's success has spurred ideas for future large-team, long-term projects for the 2024 eclipse. "For me, the biggest lesson is, you have to have something that is really exciting and challenging in order to get students involved, and in order for the general public to be involved," she says.
Results from the Eclipse Ballooning Project are forthcoming, a common refrain by eclipse researchers. "We're really excited about taking this new type of data that no one has ever taken before, and now we are in the phase when we realize no one has ever tried to analyze data like this before," Penn says. "So we're inventing the analysis as well, and it's going to take time."
More results are sure to come in 2018.