Wherever two fluids slide past each other at different speeds, the boundary between them buckles, then curls, then rolls up into vortexes. Now, a team led by David Kuridze and Friedrich Wöger of the National Solar Observatory reports that Kelvin-Helmholtz instabilities are not just visible on the Sun, but they’re ubiquitous. For most of the history of solar physics, that has ruled out every telescope on Earth. This changed when the US National Science Foundation opened the Daniel K. Inouye Solar Telescope, a 4-meter instrument in Hawaii and the largest solar telescope in the world. “The main goal was to achieve diffraction-limited performance with the telescope,” Kuridze said.