The Sun emitted its largest solar flare since 2017 on Friday, indicating that our star may be awakening from a quiet period that has lasted several years. Though the flare erupted on the opposite side of the Sun from Earth, NASA’s Solar Dynamics Observatory was able to detect its glow above the solar surface, which is visible in the upper left corner of the above image.
Solar flares, sudden bursts of light blasted out by the Sun, are sometimes accompanied by arcing ejections of hot plasma from the star. These flashes normally show up in the same area as sunspots, which are dark patches of the solar surface that are slightly cooler than other parts of the Sun.
Our star experiences solar cycles that last about 11 years and are timed by the number of sunspots visible on the surface: peak activity correlates to the largest numbers of sunspots in a cycle, while a relatively spotless Sun is considered to be in hibernation. The last cycle started in 2008, and produced a major solar storm in 2012.
These storms also cause extremely bright and vivid auroras, popularly called the Northern and Southern Lights, as the glut of charged particles from a more energetic Sun illuminates the skies. However, past incidents show that extremely powerful flares and ejections—which blast out powerful surges of X-ray and UV radiation—can also scramble satellite systems and even cause energy failures on Earth, such as a blackout in March 1989 that left millions of people in Québec without power.
While Earth was fortunately just out of the “line of fire” of the 2012 solar storm, many scientists regarded the near-miss as an ominous warning of what might happen if we have bum luck in future active periods—including Solar Cycle 25, which we may be entering right now.
For several years, the Sun has been relatively spotless and dormant, but the recent flare may hint that it is waking up and will begin to shoot out these possibly harmful pulses of particles and radiation. The flash that erupted on May 29 was classified as an M-flare, which means it was a medium-sized event that wouldn’t have posed a big risk to our civilization even if it had been pointed at our planet. X-flares are the most intense type of solar flare; it has been about two-and-a-half years since either an X-flare or an M-flare has been detected.
During its previous solar cycle, the Sun experienced two peaks of activity—known as solar maximums—in 2011 and 2014, before it quieted down. Given that this cycle got started in 2008, the recent M-flare may be a sign that the Sun is more or less on schedule with its normal 11-year period.
That said, it is still premature to declare that the Sun is rising from its slumber because the solar minimum is the absolute nadir of sunspots in cycle. As a result, solar scientists will need to confirm that sunspots are proliferating for several more months before they can definitely identify when the minimum occurred, according to NASA.
There have been a lot of jokes and memes about the year 2020 and its clear propensity for escalating chaos and uncertainty. Throwing an increasingly aggressive Sun into the mix seems to fit that narrative, especially if our star starts spitting hazardous X-flares toward Earth in the coming years.
But while solar storms could do real damage to our infrastructure, the estimated odds of a catastrophic solar storm in the next decade remain relatively low, ranging from around one to 10 percent.
Assuming you are not a space weather forecaster, the risk shouldn’t keep you up at night—that is, unless you are hoping to witness some awesome Northern or Southern Lights, courtesy of a lively Sun.