Last Updated on May 11, 2026 by John Berry
Our Sun is important to all radio amateurs. And I’ve described on this site many propagation phenomena that are caused by the Sun. It’s important therefore that I also include a good high level description of our Sun and how it does what it does.
I found a superb description of the Sun, on page 104 of Chris Lintott’s book, Our Accidental Universe, cited below. There’s no better description.
Astronomers have long known that our Sun is not … completely stable, [despite the] reassuring presence it [gives] on a balmy spring day.
Rather than being the cheerful yellow disc that shines from the sky of children’s drawings it is a superheated maelstrom of plasma, powered by nuclear reactions which take place in a core at temperatures of trillions of degrees. The energy released by these reactions, which convert hydrogen to helium, creates massive convection cells as material low in the Sun’s atmosphere is heated and rises, with colder material from near the surface sinking in turn to take its place. Allow a pan of thick soup on the stove to reach a vigorous boil, and in a similar process, bubbles will appear and splatter across your kitchen counter, though the situation in the Sun is made more complicated by the presence of our star’s strong magnetic field.
The magnetic field is inevitably twisted as the Sun spins on its axis, faster at its equator than at the poles. This differential rotation was first observed by tracking the motion of the dark sunspots which appear on the solar surface, themselves the product of the machinations and complexity of the magnetic field shaped by our star’s rapidly moving plasma. The twisted magnetic field stores energy, and that energy has, sooner or later, to be released.
When it is, in the form of either a solar flare or a more dramatic event known as a coronal mass ejection, substantial material can be flung into space. [It’s] a billion tons of matter moving towards us at over a million kilometres an hour.
[We humans] are seeking to understand this so-called solar weather and to give us advance warning of the arrival of a storm, because such events can have a significant impact on Earth and on our technology. Fortunately, we are somewhat protected by our planet’s magnetic field, which deflects the worst of the incoming storm away from the surface, while channelling incoming particles to produce the magnificent light shows we know as the Northern or Southern Lights [the aurora borealis/australis].
I’ve also described how the Sun affects radio amateurs more directly in two further pages elsewhere on this site: The Normal Sun, and The Quirky Sun.