The 1859 solar storm, known as the Carrington Event, was the most intense geomagnetic storm ever recorded. It was caused by a colossal coronal mass ejection from the sun, which took less than 18 hours to reach Earth—a trip that normally takes days. The resulting auroras were so bright that people in the northeastern U.S. could read newspapers by their light at midnight. Beyond the spectacular displays, the storm induced massive electrical currents in telegraph lines. Operators were shocked, equi