Currently the sunspot cycle is at its minimum. This picture shows a close-up view of a sunspot. Notice the dark, central umbra, where the magnetic field is predominantly vertical, and the lighter penumbra where the field is more inclined. Visible around the sunspot the granulation pattern formed by the thermal convection that transports heat up to the surface. The sunspot appears dark because its strong magnetic field inhibits this convection.
Sunspots often occur in pairs, or in groups.
The sunspots that make up the pair have opposite magnetic polarity and are linked by loops of magnetic field that arch through the Sun's corona, or outer atmosphere. The picture below, taken by the Yohkoh satellite in X-rays in 1992 near the sunspot maximum, shows these magnetic loops clearly. These observations suggest that sunspots are formed by rising tubes of magnetic flux that break through the Sun's surface. The sketch below left, due to Gene Parker, illustrates this process. Magnetic buoyancy, vorticity, and three-dimensional flux tube formation.