By Ron Cowen
The sharpest-ever visible-light images of the sun are revealing puzzling new features about sunspots, the dark regions where the sun’s powerful magnetic field is concentrated. The pictures are the first to show sun structures as small as 90 kilometers in diameter. “These images take the study of sunspots into a new regime,” says Thomas R. Rimmele of the National Solar Observatory in Sunspot, N.M. They’ve also revealed new features, some of which can’t be readily explained by any existing model of how sunspots work.
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The scientists used the Swedish 1-meter Solar Telescope on La Palma in the Canary Islands. Operating since May, it ranks as the world’s sharpest eye on the sun. To achieve its exquisite sharpness, the telescope uses an adaptive-optics system, which corrects for the blurring effects of Earth’s turbulent atmosphere. Nineteen elements of a pliable mirror within the telescope flex 1,000 times each second to adjust for rapid changes in the air above it.