Sunspot problems in older stars

Sunspots caused by magnetic fields have plagued our Sun for ages. Their frequency changes approximately every eleven years, but even in the worst case they never cover more than 0.4 percent of the Sun’s surface. However, the Sun is pretty big, which you can appreciate from the fact that a sunspot can be about as large as a whole cross section of the Earth.

On a cosmic scale, however, our Sun is only a small light and, just like there are people with more or less freckles, there are also stars th...