All of the features of the (left side of) figure below - loops, dark coronal holes, small brightened regions - have their roots in the solar magnetic field. The yellow image shows the 171 Angstrom wavelength, which corresponds to the Sun's corona at about 1 million degrees, and the black and white magnetogram image shows the magnetic field. (These are now available on the SDO web site every day.) Black is where the magnetic field is pointing towards the Sun, and white is where the magnetic field is pointing away from the Sun. The magnetic field is created in the interior, and when the field emerges it can form sunspots. However, most of the Sun is covered by tiny magnetic field elements, which connect to the "quiet" features seen in the coronal image.
Search Tag(s): 171, magnetogram, hmi