For most of us, a solar eclipse is a time to stay indoors and avert our eyes from the sun — or buy the special eyeglasses that allow us to have a look.
But for a team of faculty and undergraduates at the University of Pittsburgh known as Shadow Bandits, Saturday’s annular eclipse in Texas is an opportunity to help NASA with a major effort to gather weather information surrounding the event and the continuation of a research project started in 2017. It’s also preparation for a second trip next April, when the next full eclipse will happen in the U.S.
Sandhya Rao, a professor of physics and astronomy, will be among five faculty and staff and 12 students who leave Wednesday for Concan, Texas, about two hours west of San Antonio. That will give them some time to prepare their equipment in advance of Saturday’s event.
The group will be among about 50 university teams NASA is deploying across the country to send up weather balloons each hour for 24 hours before the start of the eclipse and six hours after it is over. Each balloon, about the size of four car tires, will be equipped with a radiosonde, an instrument to record wind, temperature, barometric pressure and humidity as the balloons rise and transmit the data by radio to receivers the team will be monitoring, said Peri Schindelheim, a senior physics and astronomy major serving as the student leader of this part of the project.
After the balloons reach a certain height, atmospheric pressure will cause them to burst, and they will fall harmlessly. That’s why a new one is deployed every hour.
During the annular eclipse, there aren’t likely to be significant changes in those conditions, but during the full eclipse next spring, there can be, especially in humidity and temperature, Schindelheim said.
“We’re not really expecting to get a lot,” she said of this week’s work. “We’re using this mostly as practice. On the off chance we get something significant, that will be a bonus.”
The second experiment will be the university’s continuing effort to study what are called shadow bands, narrow short-lived bands that are created at the edge as the moon moves to fully cover the sun with its shadow and just as that full coverage ends. A previous Pitt team started work in that area during the last full eclipse in 2017.
To study that phenomenon, the team will send a larger balloon, about half the size of a small car, up to more than 80,000 feet, said Howard Malc, 21, a senior from Fairfax, Virginia, who has a double major in computer engineering and physics. The project is designed to test whether the shadow bands only occur on the ground, which would indicate they are the result of atmospheric turbulence, or would be visible above the atmosphere due to interference effects from the thin edge of the sun.
The plan is to test high in the atmosphere and on the ground, then compare the two to see whether the turbulence matches.
This is a tricky and difficult project for a number of reasons.
First, the balloon carries a payload of about 12 pounds to gather information, but it doesn’t have a system to transmit the information back to Earth. When the balloon bursts, the payload deploys a parachute with a tracking device so the team can find it when it comes down, often as far as 20 miles away.
“We’re pretty confident we’ll get it back,” Malc said. “It would be ideal if we had it on the plane so we could start looking at the data on the way back. It’s also possible we won’t get it back for a couple of weeks.”
Also, the light differential between the shadows and the regular light at ground level is only about 1%, Rao said, enough for the human eye to see briefly but too fine a difference to easily show up in a photograph. The team will set up display screens on the ground to try to display the bands.
A previous Pitt team identified the bands during another experiment, and now this group is trying to refine the information gathered in 2017.
If the weather is favorable on Saturday, Malc will join a faculty member with a pilot’s license to gather information in the air, as well.
The majority of the trip is being paid for by NASA with contributions from Pitt and some smaller grants.
Even if the work this week produces no great revelations, it will set the team up for what could literally be a once-in-a-lifetime experience in April — the next full eclipse in North America after that won’t be until 2045.
“It’s very exciting,” Malc said. “Since I was a kid, I’ve had this dream of working with NASA. It’s cool that I’m getting to do that as a senior in college.”
Schindelheim, 20, of Long Island, said she was surprised and honored when the faculty chose her in March to be the student lead on the weather balloon project. She can’t wait to meet up with other students she met during a spring conference at the University of Kentucky who will be sending up balloons not far away in Texas.
“I’m going to be part of a real scientific experiment with NASA,” she said. “To have this opportunity now is just amazing.”
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