Large coronal mass ejection (CME) as recorded by the LASCO C3 coronagraph on 15 January 1996.
CMEs are clouds of hot (1-2 million degrees) gasses ejected from the Sun at extremely high speeds (from several hundreds to 2000 km per second). After acceleration at the Sun, they travel through interplanetary space and reach Earth in 2.5 to 5 days. When they reach the Earth, CMEs cause disturbances in the magnetosphere, which trigger auroras, make magnetic navigation at high latitudes difficult, and sometimes cause current spikes in high-voltage power lines, resulting in power outages and occasionally in destruction of power equipment. They also can damage or destroy Earth-orbiting satellites.