We have already seen that the solar corona, with its temperature in excess of 1 MK, is the site of some processes which are related to several distinct physical processes: high levels of ionization, effective thermal conduction, and emission of spectral lines over a broad range of the electromagnetic spectrum. Now we turn to a different physical property of the corona which also depends on the fact that the temperature is of order 1 MK. We shall find that, given the global properties of the Sun (specifically, its mass and radius), the corona cannot “stand still,” but must undergo expansion.