From the Quebec Blackout of 1989 to the historically intense Carrington Event 140 years earlier, geomagnetic storms are often memorable and spectacular events. This is why skygazers are excited about the recent news of an impending geomagnetic storm that will occur on Thursday evening and Friday evening, producing colorful auroras from northern California to Alabama. Though such storms are safe to view, they do carry some risk: possible widespread power outages.
The geomagnetic storm is expected to be a G4 class, according to the scale used by the U.S. National Oceanic and Atmospheric Administration (NOAA)'s Space Weather Prediction Center (SWPC). This is the second-highest level on the SWPC scale used to measure geomagnetic storms.
