Massively Powerful Solar Telescope Captures Sharpest Images Ever Of A Solar Flare

In a study published this past Monday, August 25, 2025, in the Astrophysical Journal Letters, a team of solar scientists revealed that the Inouye Solar Telescope has captured the clearest-ever images of a solar flare. Solar flares are a massive outburst of energy from the sun that is usually ejected as light and radiation.

The telescope behind the milestone, the Daniel K. Inouye Solar Telescope, is funded and managed by the National Science Foundation (NSF), a federal agency devoted to scientific and engineering research in the US. The photos captured on August 8, 2024 were taken after an X1.3-class flare, which is a powerful solar flare with effects that could reach the Earth.

The images revealed extremely clear coronal loop strands with an average width of 48.2 kilometers. Coronal loops are arch-shaped structures of hot plasma shaped by the Sun's magnetic fields. When the magnetic fields twist and snap, the loops can lead to powerful bursts of energy that often manifest as solar flares, affecting Earth's satellites and power grids.


Interestingly, the scientists involved did not set out to capture coronal loops. Their original goal was to use the Inouye Telescope's Visible Spectropolarimeter to study chromospheric spectral line dynamics. However, they discovered that when the telescope's imaging instrument was tuned to the H-alpha (656.28nm) wavelength, it could take incredible images of very faint details, particularly the fine strands of coronal loops. The telescope was able to distinguish features that are as little as 24 km apart on the surface of the sun, giving it a clarity of over two and a half times better than the next-best solar telescope.

The captured images confirm that coronal loops can be as small as 10 to 100 kilometers, which was only a theory before now, and provide first-time pictures of what could be the building blocks of the sun's magnetic architecture. Cole Tamburri, lead author of the study, says, "We're finally peering into the spatial scales we've been speculating about for years. 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."

^{Top Image Credit: NSF/NSO/AURA}
_{Body Image Credit: NASA}