How Pittsburgh researchers are trying to solve the 'shadow bands' solar eclipse mystery

Lindsay Shachnow, Pittsburgh Post-Gazette on Aug 11, 2026

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PITTSBURGH — When the moon lines up with the sun during a solar eclipse, light and dark bands can sometimes be seen racing across the ground — but only for a matter of minutes.

The phenomenon has puzzled scientists, who for centuries have struggled to pinpoint the source of light fluctuations known as “shadow bands.” The bands can typically be seen about three minutes before the moon completely blocks out the sun and for three minutes after — but not always.

As millions of people watch the moon line up with the sun for a total solar eclipse across parts of Europe on Wednesday, Pittsburgh researchers are seizing on a unique opportunity to gain new insight into the mystery.

“There's a very limited data pool to pull from to begin with,” said Giana Deskevich, a recent University of Pittsburgh graduate and key member of the “Shadow Bandits” group who conducted field research into shadow bands in 2024.

“It's very rare that we get a total solar eclipse that's in an ideal location like the United States or even Spain.”

Detecting the bands

A total solar eclipse will sweep across Greenland, Iceland, northern Russia, the Atlantic Ocean, Spain and a small corner of Portugal on Wednesday, according to NASA. Only about 3% of the sun will be eclipsed in Pittsburgh, and cloudy conditions would make it difficult to see, anyway.

That’s why David Turnshek, professor of physics and astronomy at the University of Pittsburgh, is stationed just east of Leon, Spain, as he tries to catch a glimpse of the shadow bands that could show up just before and after totality.

In Spain, Turnshek will be setting up a sensitive video camera and a light sensor to try and detect the shadow bands. During totality, the Sun will be about 10 degrees above the horizon, he said.

“Whether or not they’re seen at an altitude 10 degrees may help us solve at least part of the mystery,” he said.

There are two possible theories to explain the strange phenomenon: one is that they arise due to an atmospheric effect involving turbulence that causes the atmosphere to bend in a “chaotic way” that creates the band-like affect, he said. The other possibility is that they are due to a “diffraction-interference effect” whereby a light source passes through one or more slits, or near a sharp edge.

“It could be that both theories play a role, but they are still mysterious,” he said. “We need to explain why they are not always seen at certain locations.”

Turnshek said he began researching the shadow bands in 2017. That year, a team from the Allegheny Observatory traveled to Tennessee, near the center of the total eclipse path, to detect shadow bands on the ground and measure their light intensity, direction and speed. They also wanted to establish their existence — or lack thereof — above the turbulent atmosphere.

The experiment revealed that shadow bands existed near space, above about 99% of Earth’s atmosphere, as well as on the ground.

Deskevich has completed more recent eclipse fieldwork in April 2024 in Concan, Texas. Cloud cover may have prevented shadow bands at their site during that eclipse, she said. In Canada, shadow bands were reported across the snow.

Although solar eclipses occur routinely in some parts of the world, Deskevich said they’re uncommon in highly populated areas. Wednesday’s solar eclipse is an exception, allowing people to provide witness statements about its associated shadow bands and how wide they are or how fast they move, she said.

This potential for detecting the shadow bands on Wednesday can “confirm a lot about shadow band properties,” she said.

Where and when to watch the solar eclipse

In most places around the world that are in the path of totality, the sun will be fully eclipsed for less than two minutes.

Other areas in the Northern Hemisphere will experience only a partial solar eclipse, meaning that the moon will never completely block the sun. NASA will livestream the solar eclipse starting at 1:15 p.m. Wednesday.

In Pittsburgh, the partial eclipse will peak at 1:44 p.m. Parts of eastern Pennsylvania will have slightly higher percentages covered, including Philadelphia, where it will peak at 7%. That’s far less than parts of Alaska, where upward of 40% of the sun will be covered, according to the Weather Channel.

Wednesday’s eclipse is also a far cry from what the greater Pittsburgh region experienced when a total solar eclipse could be seen from Erie at 3:16 p.m. April 8, 2024. Pittsburgh reached 97% coverage.

Dan Malerbo, adjunct faculty teaching astronomy at the Community College of Allegheny County, said it will be “very hard” to notice the eclipse in Pittsburgh on Wednesday, which will look like the “trim of a fingernail.”

Using solar eclipse glasses is recommended. Outside of the brief phase of a total solar eclipse, when the moon completely blocks the sun’s bright face, it is not safe to look directly at the sun without specialized eye protection for solar viewing.

Viewing any part of the bright sun through a camera lens, binoculars, or a telescope without a special-purpose solar filter secured over the front of the optics will instantly cause severe eye injury.