Scientists have achieved something that almost never happens in solar research: they captured high-resolution images of an active region on the sun at the exact moment it produced two extremely powerful X-class solar flares.
Using the GREGOR solar telescope in Tenerife—the largest solar telescope in Europe—researchers zoomed in on the sun’s most energetic sunspot region of 2025 and recorded the early signs of flare ignition with astonishing clarity.
The flares also launched fast coronal mass ejections that sparked bright auroras on Earth in the nights that followed.
Strong solar flares are incredibly difficult to observe in detail from the ground. They often erupt when Earth is facing the wrong side of the sun, or during nighttime, or when weather conditions are poor.
Even on clear days, a telescope might not be pointing at the right part of the sun when a flare suddenly explodes.
Because of all these obstacles, capturing X-class flares with a ground-based instrument is extremely rare.
Prof. Carsten Denker, head of the Solar Physics section at the Leibniz Institute for Astrophysics Potsdam (AIP), says the team was unusually lucky.
On November 10 and 11, 2025, the GREGOR telescope was aimed directly at a huge, complex sunspot region known as NOAA 14274, just as it released two X-class flares. Their study, published in Research Notes of the AAS, describes what they saw.
This sunspot group was the most active on the sun in 2025. It produced 135 C-class flares, 15 M-class flares, and five X-class flares. X-class flares are the strongest type and represent the top level of the flare strength scale used by scientists.
In Solar Cycle 25—the current 11-year cycle that began in 2019—fewer than 100 X-class flares have been observed so far. The X5.1 flare on November 11 was the sixth strongest of the entire cycle.
To capture this activity, scientists used GREGOR’s advanced High-resolution Fast Imager, which includes four ultra-fast cameras.
They pointed the telescope at 28 different sections of the active region, creating a mosaic covering an area roughly 175,000 kilometers by 110,000 kilometers. It took just 14 minutes to scan the whole region, and powerful image restoration software later sharpened the fine details of each sunspot.
Only half an hour after the scan, an X1.2 flare erupted, and the early hints of this event were already visible in the images. Researchers observed strongly curved and braided penumbral fibrils—thin, hair-like structures normally arranged in straight radial lines around the sunspot’s dark core.
Their twisted shapes showed that the magnetic fields were under extreme stress. Rotating sunspots and shearing motions added even more tension, creating the conditions for explosive flare activity.
During the observing campaign, the team recorded nearly 40,000 datasets. The first images released in the study provide a preview of the remarkable scientific discoveries still to come from this rare and valuable dataset.
