Astronomers have zoomed in on small loops of plasma within a powerful solar flare for the first time, potentially revealing the fundamental building blocks of the sun's violent storms.
The images, captured with the new Daniel K. Inouye Solar Telescope in Hawaii, reveal arcs of hot gas just 10 to 30 miles wide that follow the sun’s magnetic fields. Earlier instruments could only resolve loops 60 to 100 miles wide. Inouye's images are over 2.5 times sharper.
Scientists believe these so-called "coronal loops" may in fact be the most basic pieces of solar flares — sudden explosions of energy that hurl a torrent of radiation into space and toward Earth.
The discovery is giving a new window into how our host star makes flares in the first place. Gathering such insight may lead to better space weather forecasts, perhaps preventing future solar storms from wreaking havoc on satellites, power grids, and radio signals.
"Knowing a telescope can theoretically do something is one thing," said Maria Kazachenko, a co-author in the study, in a statement. "Actually watching it perform at that limit is exhilarating."
The solar observatory sits atop a dormant volcano, Haleakalā, towering over Maui at 10,000 feet above sea level. Fittingly, the name Haleakalā means "house of the sun" in Hawaiian. But that's not why the site was selected for the telescope. The summit has special environmental conditions that allow astronomers to better view the sun's corona, the outer layer of its atmosphere.
For the study, published in The Astrophysical Journal Letters, the team measured 686 loops. They found the loops' widths tended to be similar in thickness, rather than a random mix. This suggests the telescope may finally be seeing the tiniest parts of a solar flare.
Taken in August 2024 during an X-class flare, the images show dark, threadlike arches rising over glowing flare ribbons.
Scientists have long believed that solar flares are made up of many little magnetic loops. But up until now, those loops were impossible to see. Researchers could only theorize that they existed.
If the team has indeed found the fundamental components of a solar flare — and not just larger bundles of loops — it's a breakthrough for solar storm forecasters, said Cole Tamburri, the paper's lead author. The data that could come from studying them in greater detail could improve computer models for predicting space weather.
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"It’s like going from seeing a forest to suddenly seeing every single tree," Tamburri said.
Just as Earth has seasons, the sun goes through an 11-year cycle of activity. It is quietest at the beginning and end of the cycle, but in the middle, it grows turbulent, unleashing powerful eruptions.
That peak just came, with solar activity hitting its maximum around October 2024. As a result, solar flares, along with massive blasts of plasma from the corona, have made headlines more frequently.
Even at 93 million miles away, the sun’s outbursts can affect Earth and the rest of the solar system. The planet's atmosphere and magnetic field shield people from the worst radiation, but these events can still have catastrophic consequences for life on Earth, interfering with telecommunications, navigation systems, and other critical technology.
Such events are rare but memorable. In March 1989, for example, a major flare knocked out power across Quebec, Canada, for 12 hours and even disrupted Radio Free Europe broadcasts.
