Coronal Mass Ejection (CME)

An observable change in coron al structure that occurs on a time scale between a few minutes and several hours, and involves the appearance of a new discrete, bright, white light feature in the coronagraph field of view, that displays a predominantly outward motion. The solar corona material is massive in size (they can occupy up to a quarter of the solar limb ), and frequently accompanied by the remnants of an eruptive prominence , and less often by a strong solar flare . The leading edges of fast-moving CMEs drive giant shock waves before them through the solar wind at speeds up to 1200 km per second. Some astronomers believe that CMEs are the crucial link between a solar disturbance its propagation through the heliosphere , and the effects on the Earth.