We now have some prior warning before powerful solar flares occur
A new method to predict solar flares could help us to prepare for potential disasters caused by these huge eruptions on the sun.
Predicting solar flares is difficult, because we don’t know exactly how they are triggered. While telescopes can see a flare when it occurs, providing some warning, energetic particles can arrive at Earth in as little as 8 minutes – potentially putting astronauts’ health at risk and damaging satellites before we have time to react.
“A big flare is a potential risk to our society,” says Kanya Kusano at the Institute for Space-Earth Environmental Research in Japan. “Therefore the prediction of solar flares is crucial.”
Kusano and his colleagues think they can help. The team says its “kappa-scheme” method can predict solar flares many hours before they happen. Applying the method to data from between 2008 and 2019, the group was able to predict seven of the nine largest flares, known as X-class flares, up to 24 hours ahead of time.
Previous methods of prediction have at most a 50 per cent success rate, says Kusano, relying on observations of sunspots in active regions of the sun. The kappa-scheme instead relies on the strong magnetic fields associated with solar flares.
Before a flare begins, electric currents flow along the sun’s magnetic field lines. When two of these lines overlap, they undergo a process known as reconnection, snapping the lines together and releasing a vast amount of energy – a solar flare.
The team was able to predict where and when these reconnection events were likely to occur using magnetic and imaging data from NASA’s Solar Dynamics Observatory (SDO). The two flares that couldn’t be predicted had reconnection events far above the solar surface that weren’t in the viewing field of the SDO, which is why they were missed.
Kusano hopes the method can be used to predict large solar flares in future. “We are now trying to implement this discovery for a very practical forecast of space weather,” he says.
Journal reference: Science, DOI: 10.1126/science.aaz2511
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