What Lies Beneath a Sunspot
Department of Physics
Idaho State University
Sunspots appear as dark spots on the surface of the Sun.
Temperatures in the dark centers of sunspots drop to about 3700 K (compared
to 5700 K for the surrounding photosphere). They typically last for several
days, although very large ones may live for several weeks. Sunspots are magnetic
regions on the Sun with magnetic field strengths thousands of times stronger
than the Earth's magnetic field. Sunspots usually come in groups with two
sets of spots. One set will have positive or north magnetic field while the
other set will have negative or south magnetic field. The field is strongest
in the darker parts of the sunspots - the umbra. The field is weaker and more
horizontal in the lighter part - the penumbra.