Earth encountered one of the strongest solar radiation storms in more than two decades after a powerful flare and coronal mass ejection (CME) erupted from the sun on January 18, 2026. The flare was classified as an X1.9 event, placing it among the most intense solar outbursts. Charged particles from the eruption reached Earth the next day and interacted with the planet’s magnetic field, driving a geomagnetic storm rated G4 on the NOAA severity scale. That rating denotes a severe event capable of affecting both space-based systems and Earth’s upper atmosphere, tells Live Science.
The storm reached what forecasters call S4 conditions for solar radiation, a rare level indicating a high flux of energetic particles. These particles can interfere with satellites, radio communications, and navigation systems; operators often take precautionary steps such as placing satellites into safe mode or adjusting flight paths for high-latitude aviation. Although widespread disruptions were not immediately reported, scientists and space-weather agencies monitored ongoing activity closely.
One of the most visible outcomes of the event was the appearance of auroras at unusually low latitudes. Observers across parts of the United States, including Southern California and several states in the Southeast, reported vibrant northern lights. Similar displays appeared across large swaths of Europe. Auroras occur when solar particles excite atoms in Earth’s upper atmosphere, causing them to emit light; intense geomagnetic storms can push these displays far from their typical polar zones.
This solar storm is the most significant radiation-level event recorded since 2003, eclipsing all but the most powerful flares and particle events in recent solar cycles. It underscores that, as the sun approaches the peak of its 11-year activity cycle, space weather can deliver spectacular sky shows but also pose challenges for technology that modern life depends on.