Tzu-Wei Fang will always remember February 3, 2022. It was a Thursday just after Groundhog Day, and Fang, a physicist born in Taiwan, was analyzing satellite images of a cloud of charged particles that had erupted from the sun. The incoming cloud was a coronal mass ejection, or CME—essentially a massive burst of magnetized plasma from the sun’s upper atmosphere. It looked like dozens of similar CMEs that hit Earth every year, usually making their presence known mostly through mesmerizing polar light displays.