Earth’s nearest star erupted late on January 22, belching out a solar flare. At the same time the sun launched a blast of hot gas known as a coronal mass ejection toward Earth.
A day later, when the particles slammed into the atmosphere, they set off auroras around the Arctic Circle. Fast-moving protons that came along for the ride also triggered a solar radiation storm, the biggest seen since the “Halloween storms” of October 2003.
Scientists expect such powerful solar blasts to become more common as the sun moves toward a predicted peak of activity in 2013.