Solar Luminous bridge

American amateur astronomer Howard Eskildsen made ​​an unusual photo, luminous bridge on the Sun through one of sunspots, whose nature is not fully clear to astronomers. Approximate length of luminous bridge is 20 000 kilometers. Sunspots are dark and cold (relatively)  areas of the Sun, that appear in places of output of magnetic fields, impede exchange of plasma between internal and external layers of the star. Luminous bridge often appear before the separation of sunspots in two parts. Some of the studies suggest that the processes taking place in magnetic fields and leading to emergence of luminous “bridge”, are similar with the processes  that generate  powerful  flash in the Sun.  Accordingly, it is possible that the luminous bridge is harbinger of a powerful flare on the sun.

Source: NASA