What Are Sunspots?
Sunspots are dark, relatively cool spots on the surface of the sun in a region called the photosphere. Sunspots have temperatures of about 3,800 degrees K. They can be very large, up to 50,000 kilometers in diameter.
They appear darker because they are cooler than the surrounding areas. Sunspots occur where strong magnetic forces within the sun break through to the surface. Over regions of intense magnetic activity, and when that energy is released, solar flares and big storms called coronal mass ejections erupt from sunspots.
When sunspots appear in large numbers, they trigger great sun storms that send waves of electric particles toward Earth.
These particles can interfere with radio and television broadcasts, and also create the colorful display of the auroras — the northern and southern lights. The number of sunspots is greatest about every 11 years.
The Sun has times when sunspots are born often, and the number found might be very high. These times are called Solar Maximum and that happens every 11 years or so. The last Solar Maximum was in 1989, so the next one should be in the year 2000. At Solar Maximum, there will be up to 200 sunspots on the Sun at one time.