The solar corona is a part of the Sun that spreads out from our star’s surface. The word literally means ‘crown’, which is quite appropriate for the monarch of the solar system. Because the corona is not very dense, it is hard to observe. During a solar eclipse, however, the moon blocks the glaring light from the Sun and we can see the corona in its full glory. Observatories in space keep a constant eye on this crown and send us images of its always-changing features modelled by magnetic fields and the solar wind which is made up of charged particles emitted by our star.
At over 2 million degrees Celsius, the corona is strangely much hotter than the surface of the Sun below. People are still looking for a precise explanation for this but it appears that magnetic fields are responsible for making the corona so hot. It’s nice to have mysteries like this to keep astrophysicists busy for a while.
Answered by José Monteiro.