A massive ball of plasma and accompanying magnetic field ejected from the sun is expected to strike Earth on Thursday morning, potentially triggering auroras as far south as Alabama, according to US forecasters.
This event coincides with the sun approaching or possibly reaching the peak of its 11-year cycle, during which solar activity is heightened.
In May, the planet experienced its most powerful geomagnetic storms in two decades, producing colorful displays across night skies far from the poles.
Shawn Dahl of the Space Weather Prediction Center stated, "The current anticipation is that it is going to arrive tomorrow morning to midday, Eastern time, and perhaps continue into the following day."
The coronal mass ejection (CME) is traveling through space at 2.5 million miles (four million kilometers) an hour, prompting the agency to issue a level 4 geomagnetic storm watch (G4), one level below the highest possible G5, which was observed in May. The final outcome of the storm could vary, with better predictions possible only 15-30 minutes before impact, as it crosses tracking satellites located a million miles from Earth.
Dahl also mentioned that the Federal Emergency Management Agency (FEMA), under pressure from the aftermath of Hurricane Helene and the approaching Hurricane Milton, has been informed, along with companies operating the North American power grid, to take necessary mitigation steps.
When CMEs hit Earth's magnetosphere, they can create geomagnetic storms that disrupt satellites, radio signals, and GPS systems, and potentially knock out electricity grids. The "Halloween Storms" of October 2003, for instance, caused blackouts in Sweden and damaged power infrastructure in South Africa.
May's storms disrupted precision GPS systems used by US farmers in the Midwest and caused some high-voltage transformers to trip, although large-scale grid disruptions were avoided. Dahl noted that around 5,000 satellites had to have their orbital levels corrected due to the storm's effects on the ionosphere.
For those living in suitable latitudes, potentially as far south as northern California or Alabama, auroras will be most visible away from city lights. Experts recommend using cameras or phones to capture the displays, as digital imagery can often detect them even when the naked eye cannot.