The sun had a big year in 2024. First, April brought a total solar eclipse that provided a wide swath of the continental U.S. with nearly four minutes of hushed totality. It also gave sun-gazers a chance to observe the outer layers of the sun’s atmosphere, which are normally obscured.
Then, on May 10–11, the aurora borealis seemed to appear everywhere, all at once. Reports came from North Texas, Arizona, even Alabama, Florida, and Tennessee — nearly the entire U.S. — that the night sky had turned green, purple, and pink. In places where the light was almost too faint for the naked eye, it revealed itself in camera photos. Another strong auroral show dazzled on Oct. 10–11.
The northern lights rarely extend so far south; May’s unusual light show resulted from the largest geomagnetic storm since 2003 to reach Earth’s atmosphere. A geomagnetic storm begins when the sun releases a blob of high-energy ions and electrons, called a coronal mass ejection (CME), in Earth’s direction.
Earth’s protective geomagnetic field deflects most of such blasts. During strong events like the one in May, though, those energetic particles interact with the magnetic field and gases in the atmosphere, producing the auroras. The sun also released bright flashes of light, called solar flares. (These can accompany CMEs but are separate phenomena. Solar flares travel at the speed of light, reaching Earth in eight minutes. CMEs take a few days.)
In 1859, the most powerful geomagnetic storm in recent history, called the Carrington Event, blasted Earth. Witnesses reported that the storm disrupted telegraph lines, ignited telegraph paper, and even shocked operators. Today, such an event could do far greater damage than small fires and a few zaps. Geomagnetic storms can threaten communication satellites, navigation systems, the electric grid, and more. On Halloween 2003, for instance, a powerful storm destroyed a satellite and disrupted GPS systems used for airlines, deep-sea drilling, and other applications.
The storm that struck in May, although not as strong as the Carrington Event, was rated a G5 — the most severe rating — by the National Oceanic and Atmospheric Administration (NOAA). While people admired the auroras, space weather scientists breathed a sigh of relief.
“Even though there were a lot of effects, we’re unaware of a lot of really bad impacts,” says Shawn Dahl, a space weather forecaster at NOAA’s Space Weather Prediction Center in Boulder, Colorado. “This was the most successfully mitigated extreme space weather storm in history.”
We’re better prepared than we were in the past, says Dahl. Scientists use satellites to track changes in the sun’s temperatures and magnetometers around the world to look for magnetic field fluctuations. “We can forecast a lot of these events up to three days in advance,” he says. In May, NOAA issued a warning six hours in advance, giving grid operators time to prepare and airline companies time to redirect flights to safer routes. In the future, he hopes to see a wider warning system — to alert farmers using GPS for seeding and spraying, for example.
There’s plenty to look forward to, too. In March 2025, NOAA plans to launch a satellite for solar weather prediction. And NASA announced in October that the sun had reached solar maximum for its 11-year cycle. The level of activity could continue for another year, which could mean more CMEs, more flares, and more aurora borealis, shining down in Dallas.
Stay tuned.
