What is a sunspot

Question:

What are sunspots?

Answer:

Almost everyone has probably seen it at some point: You are sitting by a campfire, looking at the embers, and when it starts to rain slightly, black spots appear in the embers - where the embers cool down due to the rain. The situation is similar with sunspots: They are dark areas on the sun's surface. They are cooler than the rest of the surface and therefore appear as dark spots. But how does such a sunspot come about?

Of course, no rain falls on the sun. Rather, the spots are caused by internal processes in the sun. Like the earth, the sun has a magnetic field, but a much stronger one. The sunspots are caused by local disturbances in the enormous solar magnetic field, which hinder the escape of heat from the hot interior of the sun to the surface. The normal surface temperature of the sun is around 6,000 ° Celsius. If you put a thermometer in a sunspot, you would measure a temperature of around 4,000 degrees Celsius - still pretty hot. Sunspots only appear so dark on images because strong filters are used in solar telescopes to darken the even lighter remaining surface. The spots appear more and more in an approximately 11-year cycle - we are currently in a phase with minimal occurrence of spots. The more sunspots, the higher the activity of the sun, which can be seen, for example, from the frequency of flares (solar flares).

The oldest written observations of sunspots by Chinese astronomers date back to 28 BC. Galileo Galilei wrote in 1613 in his "lettere solari" of his observations of sunspots and gave them today's interpretation, namely that the dark spots are structures on the surface of the sun itself. The spots can be observed directly from Earth when the sky is clear. However, it is not allowed to look into the sun unprotected, especially not with binoculars. This can cause serious eye damage. It's easier on the Internet: At www.polarlichtinfo.de (> Forecast> Sunspots) you can see a daily updated picture of the solar surface facing the earth.