We are now able to simulate (make a numerical model of) the magnetic field on the Sun, both for the whole Sun and for small features. We can see how the magnetic field changes and what effect this has.
From these results we now realise just how important
the Sun's magnetic field is. It controls the motion
of the solar plasma and
when it changes suddenly, magnetic energy can
be transferred into thermal energy (heat) and kinetic energy (motion).
We are still working on the details to understand
how exactly these effects happen.
The Sun's Magnetic Field:
One of the Sun's great mysteries is why the corona is so hot. The surface of the Sun, its photosphere, has a temperature of about 6000 degrees, but the corona is more than one million degrees.
There are lots of different calculations and
simulations being carried out to try and solve
this problem. Some theories use waves to heat
the corona, other calculations are based on
changes in the magnetic field,
which cause a myriad of small flares. None
of these models explains all of the observations,
so it might be that we need to use a combination
of different models.
The Hot Corona: