Sunspots
Sunspots (dark areas) on the surface of the Sun. Sunspots are areas of magnetic activity that are cooler than the rest of the Sun's surface. They range in size from hundreds to thousands of kilometres across. The darkest regions (nearly vertical magnetic fields) are the umbras, surrounded by penumbras (bronze regions). The yellow background consists of convection cells called solar granules, each around 1000 kilometres across. This sunspot (part of AR 1793), developed this shape after its first appearance several days earlier (C019/3779). It was observed with a Baader white light filter on 21 July 2013.
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