Coronal Loops Flicker Right Before the Sun Unleashes Big Flares

Predicting space weather is more complex than predicting traditional weather here on Earth. One of the most unpredictable kinds of space weather is solar flares, which explode out from the surface of the Sun and can potentially damage sensitive equipment like electrical grids and the ISS. The Carrington Event, one of the most violent solar storms in history, literally caused telegraph lines to catch fire when it occurred in 1859 – a similar storm would be much more devastating today. Due to their potentially destructive potential, scientists have long looked for ways to predict when a storm will happen, and now a team led by Emily Mason of Predictive Sciences, Inc. in San Diego thinks they might have found a way to do just that.

Solar flares typically occur in highly magnetic areas of the Sun. However, they aren’t the only events that occur in those regions—another, less potentially hazardous event is a coronal loop. These look like giant arches of particles that start from and connect back to the Sun’s outer layer, also called its corona. 

Scientists have long thought there might be some sort of tie between coronal loops and the solar flares that emerge from the same region. However, the lifespan for coronal loops ranges from seconds to weeks, and scientists have yet to find a valid link between that metric, or any other, and the occurrence of a solar flare in the same region.

Dr. Mason and her colleagues thought they might take a different approach. They got some observational time on the Solar Dynamics Observatory (SDO), a telescope in geosynchronous orbit explicitly designed to observe the coronal layer. They used SDO’s extreme ultraviolet wavelength observational capabilities to observe coronal loops in regions that eventually formed a flare versus those that didn’t.

They observed areas that produced around 50 flares and found that the amount of variability in extreme ultraviolet light the coronal loops in those areas put off was much higher than in the areas that didn’t produce a flare. Essentially, the coronal loops acted like “flashing warning lights” in a certain kind of light spectrum, according to a press release from NASA’s Goddard Institute, some of whose scientists contributed to the paper. 

The discovery was critical because the flashing appeared to take place consistently a few hours before a flare was formed. In technical terms, they accurately predicted the onset of a flare about 2-6 hours beforehand, about 60-80% of the time. That might not seem like great odds and even lesser warning, but some warning is better than none. When given the decision between frying half of the Earth’s electrical grid in a few hours and taking preventive measures, I think policymakers would at least appreciate the opportunity to have a choice.

There are some other nuances in the data, such as stronger flares appear to be predicted by earlier peaking flickering, however more work still needs to be done. Ultimately, this research aims to develop a system of automatically warning the appropriate authorities if there is a potentially hazardous solar event coming our way, but without so many false positives that they feel the system is crying wolf.

That automated system is still a little way off, but this research is a step in the right direction. SDO was initially launched in 2010 and has long outlived its original 5-year mission plan. However, there are plenty of instruments constantly watching the Sun, and undoubtedly, there will be more soon. Maybe they will someday contribute to finalizing a system that will one day save civilization from an avoidable catastrophe.

Learn More:
NASA – NASA Solar Observatory Sees Coronal Loops Flicker Before Big Flares
Kniezewski et al – 131 and 304 Å Emission Variability Increases Hours Prior to Solar Flare Onset
UT – New Research Indicates the Sun may be More Prone to Flares Than we Thought
UT – High-Resolution Images of the Sun Show How Flares Impact the Solar Atmosphere

Lead Image:
NASA’s Solar Dynamics Observatory captured this image of coronal loops above an active region on the Sun in mid-January 2012. The image was taken in the 171 angstrom wavelength of extreme ultraviolet light.
Credit – NASA/Solar Dynamics Observatory

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