Solar flares are powerful blasts of energy from the Sun that are able to wreak havoc on Earth’s magnetosphere when they’re pointed in the right direction.
Now, thanks to the clearest images ever taken of a flare, scientists are finally peeking into the Sun’s smallest hidden features.
On August 8, 2024, something remarkable happened: an X1.3-class flare erupted from the Sun’s surface. And this time, Earth had the perfect view.
Thanks to clear skies and ideal timing, astronomers captured the flare using the Daniel K. Inouye Solar Telescope in Hawaii.
It’s the largest solar telescope on Earth and has the kind of resolution that other telescopes can only dream about. What it revealed is changing the game.
Dangers of solar flares
Solar flares are dangerous bursts of energy that can mess with satellites, radio signals, power grids, and even airplane navigation.
These flares shoot out when magnetic field lines on the Sun snap and reconnect.
But understanding exactly how and where that happens has been tough – because the structures involved are incredibly small. But the new images will change all that.
What the telescope captured
During this flare, scientists saw something they had never been able to see before: ultra-thin coronal loops. These are delicate arcs of hot plasma that trace the Sun’s magnetic field lines.
They usually appear right before or during solar flares. The team measured the loops and found they were only about 30 miles (48 kilometers) wide – some as thin as 13 miles (21 kilometers).
For comparison, most solar loops we’ve seen before were closer to hundreds or even thousands of miles across.
Before this, scientists could only guess that loops might be this small. “We’re finally peering into the spatial scales we’ve been speculating about for years,” said Cole Tamburri, lead author of the study.
“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.”
Unexpected discovery
What’s astonishing is that the team wasn’t even searching for this. They were going to investigate the Sun’s chromosphere – the zone just above the surface – using a different device.
But the observations in the Visible Broadband Imager, which targets the H-alpha wavelength (a particular kind of red light at 656.28 nanometers), proved to be a treasure trove.
The images showed hundreds of these fine strands arching high above the Sun’s surface, tightly packed together.
Some were just barely wide enough to be picked up by the telescope, which can resolve details down to about 15 miles (24 kilometers). That’s more than twice the resolution of any other solar telescope in use.
“Knowing a telescope can theoretically do something is one thing,” said Maria Kazachenko, one of the study’s co-authors. “Actually watching it perform at that limit is exhilarating.”
The detail was so fine that scientists started to wonder if they were finally seeing the Sun’s building blocks.
Not just loops inside loops, but single, distinct magnetic threads. If that’s true, it could completely reshape how scientists model solar flares and the processes that drive them.
Earth and solar flares
There’s a practical side to all this, too. Solar storms can knock out technology that we depend on. GPS, power systems, and internet cables all feel the effects when the Sun sends out a powerful flare.
Better models based on real data help scientists make more accurate forecasts. If we can spot the tiniest structures forming before a flare, we might someday predict them earlier or with better precision.
“This is the first time the Inouye Solar Telescope has ever observed an X-class flare,” Tamburri said. “These flares are among the most energetic events our star produces, and we were fortunate to catch this one under perfect observing conditions.”
The telescope itself is run by the National Science Foundation’s National Solar Observatory (NSO), and this kind of discovery is exactly what it was built for.
Tamburri is part of a program that trains Ph.D. students to work with Inouye data so that more people in the field can learn how to use its powerful tools.
Solar images prove theories right
Theories have long predicted that magnetic loops on the Sun might be as thin as 6 miles (10 kilometers) wide, but no one could actually confirm it. Now, with Inouye, they can see it directly.
“Before Inouye, we could only imagine what this scale looked like,” Tamburri said. “Now we can see it directly. These are the smallest coronal loops ever imaged on the Sun.”
Even the look of the flare was striking. The image showed threadlike dark loops against a bright background, with two clear flare ribbons: one short and triangular, and one long and curved like an eyebrow.
“Even a casual viewer would immediately recognize the complexity,” Tamburri said. “It’s a landmark moment in solar science,” he added. “We’re finally seeing the Sun at the scales it works on.”
And that’s exactly the kind of vision scientists need to make sense of the star that runs our entire solar system.
The full study was published in the journal The Astrophysical Journal Letters.
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