A coronal mass ejection is an eruption that hurls a billion tons or more of magnetized plasma from the Sun's corona into space. Unlike a solar flare, which is a burst of radiation arriving in minutes, an ejection is physical material that takes one to three days to reach Earth. If its magnetic field is oriented opposite to Earth's, it couples strongly and drives a geomagnetic storm capable of disrupting satellites, navigation, and power grids. The 1859 Carrington Event, the strongest on record, set telegraph lines sparking.