The Sun as Never Before Seen
As parts of Europe prepare for a solar eclipse on August 12, astronomers have unveiled the most zoomed-in image ever of the Sun’s surface. The observations reveal swirling eddies on the solar surface—caused by an unstable mixing of magnetically infused plasma. The detection of these vortex-like features provides new insights into the magnetic processes that power solar flares and may also heat the Sun’s million-degree corona [1].
The solar snapshots were captured by the 4-m Daniel K. Inouye Solar Telescope in Hawaii, which is the world’s largest solar telescope. The images show details on the Sun’s surface at the 20-km scale, more than a factor 2 smaller than previous observations with other telescopes. David Kuridze from the National Solar Observatory (NSO) in Colorado and his colleagues collected the images at a rate of about one every 3 seconds, enabling them to track changes on the Sun’s highly dynamic surface.
The images display bright and dark patches surrounded by lace-like boundaries adorned with small spiraling features. The team interprets these vortex-like spirals as the result of the Kelvin-Helmholtz instability (KHI), a long-established effect that occurs at the interface between two fluids moving at different speeds. This instability drives ocean waves on Earth and the billowing whorls that appear between contrarotating bands in Jupiter’s atmosphere.
The KHI was expected to play a role on the Sun’s surface, where flows of hot plasma mingle with magnetic fields. The magnetic fields on the solar surface tend to concentrate into narrow regions, where they slow the motion of the plasma. This slowdown causes a cooling of magnetic regions, leading to dark patches—the largest of which have been observed since antiquity as sunspots.
But what hadn’t been seen before were the boundaries between magnetic and nonmagnetic regions, where the flow speed should be changing abruptly. “What makes our observations unique is that, for the first time, we resolve boundary deformations around these magnetic elements and identify them as KHI patterns,” Kuridze says. Although he and his colleagues expected to see signs of KHI, they were surprised by how extensive the vortex-like features are on the Sun.
The findings could have implications for our understanding of energy transport in the solar atmosphere, explains NSO’s Friedrich Wöger. The continuous twisting of KHI features may lead to “braiding” of magnetic-field lines into larger magnetic structures, which produce solar flares and coronal mass ejections. In addition, KHI activity on the Sun’s surface may be the starting point for injecting heat into the Sun’s million-degree corona.
“We’ve seen the Sun’s large-scale events, but we’ve been missing some of the small-scale physics that power these events—the ‘tiny engines’ that drive solar activity, Wöger says. “KHI may be one of these engines.”
–Michael Schirber
Michael Schirber is a Corresponding Editor for Physics Magazine based in Lyon, France.
References
- D. Kuridze et al., “Ubiquitous Kelvin–Helmholtz instabilities driving plasma mixing on the Sun,” Nature (2026).