Adventist Youth Honors Answer Book/Stars/Sunspot

The Sun with sunspots

A sunspot is a region on the Sun's surface that is marked by a lower temperature than its surroundings and intense magnetic activity, forming areas of low surface temperature. Although they are blindingly bright, at temperatures of roughly 4000-4500° K, the contrast with the surrounding material at some 5700° K leaves them clearly visible as dark spots. If they were isolated from the surrounding photosphere they would be brighter than an electric arc.