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. Sunspots 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.
Sunspots occur 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.