Give me a crash course in . . . solar storms


News reports have been mentioning a solar storm this week. What’s that?The sun is a fiery and gaseous place. And every so often a “coronal mass ejection”, or solar storm, erupts at its surface and gets flung into space. It travels at millions of kilometres per hour and can contain billions of tonnes of hot gas. Sometimes, Earth lies in the path of these travelling solar storms, which can take days to make the 149m km trek from the sun. That’s what happened this week. Two solar flares kicked off, and the activity reached Earth on Wednesday and Thursday.

So what happens on Earth if we end up in the path of one of these solar storms?A solar storm carries with it a whoosh of magnetic fields and highly energised particles. When the storm hits Earth’s magnetic field the interaction can create the aurora borealis, the colourful displays of the Northern Lights.

A strong solar storm could make the light show visible in more parts of Earth than usual.

A powerful solar storm that hits Earth might also interfere with our telecommunications systems, says Dr Peter Gallagher, a solar physicist at Trinity College Dublin.

“It has been known for a long time, even since the 1850s, that the sun can have an effect on telecommunications systems,” he says. “On the cable between Valentia and Newfoundland they would see the currents fluctuate when solar activity goes up or down.”

Today we use satellites for telecommunications and to navigate by GPS. A solar storm can interfere with those spacecraft, or even banjax them altogether. “You could lose satellites worth hundreds of millions of euro,” says Gallagher. At the time of writing, this week’s activity hadn’t seemed to cause too much of a problem, though.

Okay, so we see pretty lights, and there’s a chance the phones go a bit wonky. Are we likely to be in the way of more solar storms?The short answer is: probably. “We have just come out of a very quiet period,” says Gallagher. “In 2013 the sun will reach solar maximum and we will get several solar storms per day. A fraction will hit Earth.”

Can we predict when a solar storm will hit?We’re getting better at forecasting solar storms. Scientists, including the solar physics group at Trinity led by Gallagher, have been analysing data from a pair of spacecraft, run by Nasa, that gather data on solar storms.

“We have written software that automatically tracks what’s going on at the sun’s surface,” says Gallagher. “When something happens on the sun our software kicks in and makes a lot of measurements automatically and then makes forecasts. We can typically give a two- to four-day warning of something hitting Earth.”