Geomagnetic storm set for June 4-5, aurora could brighten

A significant geomagnetic storm is expected to impact Earth on Thursday, June 4, and continue into Friday, June 5, potentially creating widespread displays of the northern lights across North America and parts of Europe. The U.S. National Oceanic and Atmospheric Administration’s Space Weather Prediction Center has issued a watch for a strong, or G3-level, geomagnetic storm, with conditions possibly intensifying to severe G4 levels.

The event is driven by multiple coronal mass ejections (CMEs)—clouds of solar plasma and magnetic fields—that erupted from the sun earlier this week. These eruptions originated from a large and volatile sunspot region, designated 4455, which is directly facing Earth. This region produced several powerful solar flares, including an X-class flare, the most intense category, on June 2.

Forecasters note that one of the later, faster-moving CMEs has overtaken an earlier eruption, merging to form what scientists describe as a "cannibal" CME. This phenomenon can result in a more powerful and longer-lasting geomagnetic disturbance when it interacts with Earth's magnetic field. The combined CMEs are projected to begin arriving in the mid-to-late afternoon...