The most extreme weather of all rarely gets a mention, even in the UK where we’re famous for our weather talk. Far above our heads the Earth is regularly hit by colossal, tsunami-like waves of scorching gas and savage, supersonic winds from space.
The culprit for this extra-terrestrial weather is sat at the centre of our solar system. The familiar pictures of our Sun that portray a plain, incandescent orb, serenely holding the planets in place, couldn’t be further from the truth. The Sun is a rowdy place.
One of the most spectacular forms of space weather are Coronal Mass Ejections, where the Sun sporadically throws out billions of tonnes of hot gas and magnetic field into space.
The Sun also generates its own wind, which ranges from “breezes” to “hurricanes”. It’s all on a much bigger scale though – even average solar winds are much more ferocious than anything we could ever experience, with speeds varying between a gentle 500,000 miles per hour to a gusty 2,000,000 mph.
These winds carry with them a part of the Sun’s atmosphere, a million-℃ gas composed of highly energetic electrons, protons and alpha particles. The winds are accelerated along the sun’s outstretched, tentacle-like magnetic field, which originates deep under its surface and extends out past Earth to the edges of the solar system.
Being able to forecast the solar wind has its problems though. For example, we know they predominantly originate in darker, less dense patches of the Sun’s atmosphere known as coronal holes, however we are still unable to locate the other significant sources that must contribute to the wind. More importantly, we don’t have a clear explanation of how the winds are heated and accelerated.
Blowin' in The Wind
My colleagues and I were interested in the processes underlying these tempestuous winds. In a study published in the journal Nature Communications, we investigate powerful magnetic waves, known as Alfvén waves, located in the regions where the solar wind originates. These waves cause the Sun’s magnetic field to violently sway back and forth at tens of thousands of miles per hour, transporting energy around the star’s atmosphere and out into space.
