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Add solar superflares to the list of natural disasters of concern.
Superflares are extremely strong solar flares – explosions with energies up to ten thousand times that of typical solar flares.
Why worry? “A new study of 56,000 sun-like stars reveals that other stars like ours may experience powerful superflares about once per century, shedding light on the potential for rare but extreme solar outbursts,” according to a statement from the American Association for the Advancement of Science, which published the study. The findings suggest that our sun might produce superflares at a similar rate.
And if one happens, it could fry our communications satellites and earth-bound power grid.
“We were very surprised that sun-like stars are prone to such frequent superflares,” said study lead author Valeriy Vasilyev from the Max Planck Institute for Solar System Research in Germany. Earlier studies by other research groups had found average intervals of a thousand or even ten thousand years.
More:Want to see the northern lights? Good news: Experts predict years of awesome aurora viewing.
What is a solar flare? A superflare?
Solar flares are intense, localized bursts of electromagnetic radiation from the sun, releasing immense energy over short periods. These events impact Earth’s upper atmosphere and can occasionally cause communications blackouts.
Superflares, by contrast, are rare, higher-energy outbursts – potentially much more powerful than the largest solar flares seen on the sun. Superflares, which release amounts of energy of more than one octillion joules within a short period of time, show themselves in distant stars as short, pronounced peaks in brightness.
“We cannot observe the sun over thousands of years,” said Sami Solanki, director at the Max Planck Institute and study coauthor, explaining the basic idea behind the research. “Instead, however, we can monitor the behavior of thousands of stars very similar to the sun over short periods of time. This helps us to estimate how frequently superflares occur,” he said.
What if a superflare hit the Earth?
If a solar superflare ever strikes Earth, the first thing to hit us will be an intense flash of X-ray and ultraviolet radiation, according to a 2019 study about the phenomenon in the Proceedings of the National Academy of Sciences.
“This would disrupt the ionosphere, scrambling the satellite navigation signals needed in critical services and infrastructure,” the study said. “The burst of radiation would heat the outer layers of Earth’s atmosphere making them expand, increasing drag on satellites so much that some might be lost.”
Next, according to the 2019 study, a wave of high-energy protons, accelerated by shockwaves in the sun’s atmosphere, would hit Earth. These could further cripple satellites, compromising global communications. “High-energy particles can permanently damage processors,” said Lockheed Martin astrophysicist Karel Schrijver in the 2019 study.
In a worst-case scenario, if the flare also spawns a supersize coronal mass ejection that happens to be aimed at Earth, it could cause a violent geomagnetic storm, inducing electric currents that could be strong enough to paralyze power grids. A nine-hour blackout in Quebec in March 1989 was caused by a much more modest coronal mass ejection.
When could a superflare occur?
The new study does not say when the sun might emit a superflare. However, the results urge caution.
“The new data are a stark reminder that even the most extreme solar events are part of the sun’s natural repertoire,” study coauthor Natalie Krivova, also from the Max Planck Institute, said in a statement.
During the infamous Carrington event of 1859, one of the most violent solar storms of the past 200 years, the telegraph network collapsed in large parts of northern Europe and North America.
According to estimates, the associated flare released only a hundredth of the energy of a superflare. Today, in addition to the infrastructure on the Earth’s surface, satellites would be at particular risk, the new study warns. Satellites are used for some television and phone services, GPS, credit card authorization and weather and climate monitoring, among other uses.
The study was published Thursday in the peer-reviewed journal Science, a publication of the American Association for the Advancement of Science.
