The Solar Corona (3) ...
The density of the corona is very small compared with the density at the surface, but
the corona has a temperature that is actually much higher than that of the solar surface.
Temperature of the Corona and Magnetic Fields
The temperature rises rapidly above the photosphere and chromosphere to around a million K in the
corona, as illustrated in the adjacent image.
The reason for this rapid rise in temperature is not well understood: why should the corona be a thousand times
hotter than the surface, when the surface is closer to the core where the energy is being produced?
The extremely high temperature of the corona is thought to be associated with effects of the solar magnetic field,
which can store and transport energy from lower regions of the Sun to the corona. However, the details of how this
heating takes place are only partially understood.
