Not just auroras. Disruption of critical infrastructure: electric grid, pipelines, transportation, communications, satellites, navigation. Worst US case: Stoppage of food/fuel/pharmaceutical production/delivery, multiyear recovery of electric grid, up to 90% casualties. Can this come to pass? 1859 Carrington event disrupted telegraph system, sparked fires. 1921 NY Railway Storm disrupted signals/switching, halted NYC trains, burned down railway station. Equipment in both cases was far more robust than modern semiconductor electronics. How would this affect modern technology? Why are NY and Quebec more vulnerable? What are coronal mass ejections? Solar flares? This course covers solar storms, Earth’s shield (magnetosphere), resulting geomagnetic storms and terrestrial effects, historical examples, and mitigation measures.