The most obvious feature on the sun this week was a substantial coronal hole, the mottled dark area expanding out from the top of the sun (Mar. 5- 8, 2018). Coronal holes appear dark in certain wavelengths of extreme ultraviolet light like the one you see here. They are areas of open magnetic fields from which solar wind rushes out into space. That solar wind, if Earth-directed, can create some minor aurora outbursts, usually closer to the poles. On March 7 the structure stretched more than 700,000 km from the sun's north pole most of the way to its equator. Credit: Solar Dynamics Observatory, NASA.
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