One may expect the explosions of the sun to come from nuclear reaction of suns core. But in reality all source of solar activity is sun's magnetic field. Since earth rotates as a solid, its magnetic field is simple. We have 2 poles; North Pole and South Pole. So we can use compass very easily to use to find our way in earth. But in the sun there are 1 million to 10 million poles.
Suns magnetic field is like tangled web. Even though it's held together by gravity the plasma does not rotate uniformly. Plasma in equator rotates in 25 earth days. While in the poles it takes roughly 35 days to circles once. It is called differential rotation.
Though magnetic field lines are invisible we know they exist in sun by looking at coronal loops that rise up to solar atmosphere. These loops of plasma perfectly outline the magnetic structures that support them from below.