The sun put on a private concert.
Ribbons of light braided across its face. Threads of fire snapped and curled, like embroidery stitched with plasma.
On Aug. 8, 2024, the National Science Foundation’s Daniel K. Inouye Solar Telescope (DKIST) trained its Visible Broadband Imager (VBI) on an X1.3-class solar flare and captured H-alpha images so sharp they reveal coronal loop strands averaging 48.2 km across — and, in places, as slim as about 21 km. These are not guesses; they are measurements published and released by the National Solar Observatory.
The pictures are stunning. What once looked like smooth, glowing arches now resolve into a forest of hair-thin lanes: dark, delicate threads set against a searing backdrop. Bright flare ribbons race across the scene while dozens of narrow loops arc and fade. It’s both fragile and ferocious — a sculpted moment of raw energy.
“Before Inouye, we could only imagine what this scale looked like,” said Vincenzo Tamburri, a DKIST scientist. “Now we can see it directly. These are the smallest coronal loops ever imaged on the sun.” That line says it plainly: the telescope has taken an idea and made it visible.
Why H-alpha?
Think of it as tuning to a single color of sunlight that highlights the sun’s lower atmosphere. By isolating that wavelength (656.28 nanometers), DKIST’s VBI teases out the fine structure that other filters wash away. The instrument’s resolving power is roughly 24 km, a leap large enough to turn fuzzy ribbons into tidy, countable threads. That clarity — more than 2.5 times better than earlier ground-based telescopes — is what made these images possible.
A Closer Look at Coronal Loops
Coronal loops are arches of superheated plasma that trace invisible magnetic lines above the sun’s surface. When those magnetic lines twist and reconnect, they release energy in flares. Until now, most telescopes blurred those arches into fat ribbons, and astronomers could only guess whether a loop was one tidy strand or a bundle of many. DKIST’s images change that, allowing scientists to test whether the sun’s basic building blocks are fine filaments or thicker tubes.
The discovery had a dash of serendipity. Observers had planned to prioritize spectral studies with DKIST’s Visible Spectropolarimeter (ViSP), but the VBI imaging revealed unexpectedly fine structure — a surprise that became the headline result. The frames released by NSO were taken during the flare’s decay phase, the afterglow when the sun’s magnetic ropes settle and the most intricate loopwork becomes visible. The full scene spans roughly four Earth diameters, so these tiny threads sit inside an enormous, violent stage.
This isn’t just pretty photography. Knowing whether flare energy is packed into ultra-thin strands or smeared across broader loops affects the physics. The scale of the threads influences how heat and particles move, and that changes the models scientists use to predict flares. Better models help anticipate space weather that can nudge satellites, disrupt radio and strain power systems on Earth.
NSO’s team has made the images and measurements public. If you love high-drama space photography, dive into the image pack and zoom until those tiny loops look like embroidery. These frames are scientific data, but they behave like art: violent, intricate and impossibly beautiful.
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