MDI Magnetogram

The MDI (Michelson Doppler Imager) images shown here are taken in the continuum near the NiI 6768 Angstroms line. The most prominent features are the sunspots. This is very much how the Sun looks like in the visible range of the spectrum (for example, looking at it using special 'eclipse' glasses: Remember, do not ever look directly at the Sun!). The magnetogram image shows the magnetic field in the solar photosphere, with black and white indicating opposite polarities.

Source: NASA / ESA / SOHO / LASCO, EIT and MDI teams