Figure 9-11

Zeeman Splitting by a Sunspot’s Magnetic Field (a) The black line drawn across the sunspot indicates the location toward which the slit of the spectroscope was aimed. (b) In the resulting spectrogram, one line in the middle of the normal solar spectrum is split into three components by the Sun’s magnetic field. The amount of splitting between the three lines is used to determine the magnetic field’s strength. Typical sunspots have magnetic fields some 5000 times stronger than Earth’s magnetic field.