How is the Solar Corona Heated?
The energy source that keeps the Sun hot and shining is at the center of the Sun. Therefore, the temperature is expected to fall as you move away from this central “heater”. The temperature of the solar atmosphere, however, instead of dropping as you move away from the Sun, actually increases as you move outward from the photosphere to the corona! (The temperature eventually reaches a maximum and begins to drop in the outer corona.) How is this possible? What we know is that the outer layer of the Sun is very turbulent, like a pot of boiling water. This layer of the Sun is called the convection zone. The magnetic field in the corona is anchored in the convection zone. The gas pressure in the convection zone dominates the magnetic field pressure. As a result, the magnetic field is dragged around and twisted by the turbulent motions of the gas in the convection zone. These motions can propagate up the magnetic field lines to the corona, where the magnetic field pressure is greater than t
