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Newly released photographs of the sun captured during the Aug. 12 total solar eclipse reveal the sun’s outer atmosphere in unprecedented detail.
The images, released by researchers working as part of the Solar Wind Sherpas project coordinated by the University of Hawaii, also show rare structures in the solar wind known as smoke rings. Named for their resemblance to the circles blown by smokers, these vortices were first identified in solar eclipse photographs captured in 2008. The researchers had long struggled to explain the processes behind their formation. They now know the rings are a result of the temperature differences in the coronal plasma and spread along the sun‘s magnetic lines deep into interplanetary space.
“This year, we have managed to capture those smoke rings really well,” Miloslav Druckmüller, a professor of mathematics at the Brno University of Technology in the Czech Republic, who leads the image processing efforts for the Solar Wind Sherpas Team, said in a statement. “They are beautifully twisted vortices and there are very many of them in the corona.”
The images, taken from the Pico Trigaza mountain in Spain, also reveal a giant coronal hole — an opening in the sun’s magnetic field lines — through which solar wind can escape more readily at very high speeds of up to 500 miles per second (800 kilometers per second).
Coronal holes are cooler regions in the sun’s atmosphere that appear darker in extreme ultraviolet and X-ray images taken by probes in space. They form in regions where the sun’s magnetic field lines extend outward into space rather than looping back to the surface, allowing high-speed solar wind to escape. These structures can persist for weeks or even months.
(Image credit: Brno University of Technology/Miloslav Druckmüller)
Solar eclipse photography provides a unique vista into the processes taking place in the sun’s upper atmosphere, the corona, which remain hidden even to cutting-edge space-based observatories.
Space probes and astronomical telescopes on Earth rely on instruments known as coronagraphs to view the corona. As the corona is a million times dimmer than the sun’s surface, researchers need to obscure the visible solar disk with an occulter to view it. This occulter, located inside the telescope, has to cover a larger area than just the solar disk itself to protect the images from the effects of diffraction.
During a total solar eclipse, the moon naturally blocks the sun’s bright disk, allowing scientists to capture exceptionally detailed views of the inner corona that are difficult to obtain with conventional coronographs.
