Inouye Telescope Captures "Landmark" Images of Solar Flares

Solar flares are intense bursts of radiation emitted by the sun during solar storms, standing as the most powerful explosions in the solar system. According to NASA, the biggest flares can have as much energy as a billion hydrogen bombs, and yet astronomers have only recently obtained record-breaking photographs of the phenomenon.

On August 8, 2024, the Daniel K. Inouye Solar Telescope at Maui’s National Solar Observatory (NSO) captured the most detailed shots ever of a solar flare. The imagery featured “dark coronal loop strands” with “unprecedented clarity,” per a statement, marking a potential breakthrough in resolving the “fundamental scale of solar coronal loops.” These “loops,” or arches of plasma, follow the sun’s magnetic field lines, often portending the solar flares that release a sudden rush of energy. Even from millions of miles away, such blasts can significantly impact infrastructure on Earth, whether it be our power grids or communications systems.

“This is the first time the Inouye Solar Telescope has ever observed an X-class flare,” Cole Tamburri, a solar physicist at the University of Colorado Boulder, says. “These flares are among the most energetic events our star produces, and we were fortunate to catch this one under perfect observing conditions.”

Before now, scientists couldn’t fully determine the size of these plasma loops, and could only speculate that they could measure anywhere from 10 to 100 kilometers (about 6 to 62 miles) in width. Confirming those theories has been virtually impossible, due to resolution limitations in older telescopes. The new data gathered by the Inouye Solar Telescope, however, offers a high-definition glimpse into the loops—both big and small—for the first time. On average, loops measured about 30 miles across, but some were as small as 13 miles, which also happens to be right at the telescope’s resolution limit.

“Before Inouye, we could only imagine what this scale looked like,” Tamburri explained. “Now we can see it directly. These are the smallest coronal loops ever imaged on the sun.”

When tuned to the H-alpha filter, Inouye’s Visible Broadband Imager (VBI) instrument can resolve features down to about 15 miles—more than 2.5 times sharper than the next-best solar telescope, per NSO.

“We’re finally peering into the spatial scales we’ve been speculating about for years,” Tamburri adds. “This opens the door to studying not just their size, but their shapes, their evolution, and even the scales where magnetic reconnection—the engine behind flares—occurs.”

One fruitful discovery is that these loops might be “elementary structures,” rather than simply “bundles.”

“If that’s the case, we’re not just resolving bundles of loops; we’re resolving individual loops for the first time,” Tamburri says. “It’s like going from seeing a forest to suddenly seeing every single tree.”

Scientists hope that this new imaging can lead to improvements in solar flare modeling and a better understanding of the magnetic field in the sun’s corona. But even the most casual viewer will find much to enjoy in these photos: deep-red ribbons arch and swirl across a fiery plain, with bright flares peppered throughout. Such detail would never have been possible to achieve without the Inouye Solar Telescope, NSO claims.

“It’s a landmark moment in solar science,” Tamburri concludes. “We’re finally seeing the sun at the scales it works on.”

The Daniel K. Inouye Solar Telescope at Maui’s National Solar Observatory (NSO) captured the most detailed shots ever of a solar flare.

A high-resolution image of the solar flare from the Inouye Solar Telescope. The image is about 4 Earth-diameters on each side. (Photo: National Solar Observatory)