A coronal mass ejection erupting from the Sun in June 2015.
Space weather can be beautiful, such as the incredible aurorae seen around the world in May, and dangerous, damaging technology both temporarily and permanently. Predicting space weather is incredibly important. And researchers now report a better understanding of coronal mass ejections, a crucial development in knowing what kind of danger lies in the future.
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Coronal mass ejections, or CMEs, are powerful expulsions of magnetic field and plasma from the Sun. The plasma is made up of charged particles and when it hits our planet, colliding with Earth's magnetosphere, it can cause geomagnetic storms, sometimes sending satellites and other technology on the fritz. These particles are carried by a magnetic field towards the polar regions, where they hit the atmosphere creating gorgeous auroras.
Crucial to predicting the intensity of a solar storm is the speed of CMEs after they have erupted from the Sun. This is something usually measured once the CME has been released. Now scientists have found a way to predict the speed of the event before the eruption.
“There are ways to look into the CMEs before they even have erupted from the Sun, and that is by looking into their source region evolutions,” lead researcher Dr Harshita Gandhi, a solar physicist at Aberystwyth University, told IFLScience.
Gandhi and her team looked at these "active regions" on the Sun, where CMEs are born. They measured the properties of the region before, during, and after the release of a CME. They were able to estimate a parameter called "critical height". Above that height, the magnetic field becomes unstable and can lead to the emission of a CME. This height, they found, is linked to the speed.
“The higher the critical height you find in the corona in your active region, the faster the CME's speed you would expect from that active region,” Dr Gandhi explained.
So by estimating the height, they can predict the likely speed of the CME. And with that, predictions can be made about how dangerous a certain CME might become. The Sun is continuously monitored by space agencies around the world so it shouldn’t be too complicated to implement these kinds of parameter estimations.
But that's not the end of it. To improve these predictions, the team plans to add another parameter.: the strength of the magnetic field will help strengthen the estimate of the speed. This research expands what we know of the Sun as well as improves our space weather forecasting capabilities, which in a technological world is vital should we ever see a Carrington Event-level event again.
Dr Gandhi presented the team’s findings today at the Royal Astronomical Society’s National Astronomy Meeting in Hull, UK.
