mass ejection

A coronal mass ejection (CME) is an ejection of material from the solar corona, usually observed with a white-light coronagraph.

The ejected material is a plasma consisting primarily of electrons and protons (in addition to small quantities of heavier elements such as helium, oxygen, and iron), plus the entrained coronal magnetic field.

The first detection of a CME was made on December 14, 1971 by R. Tousey (1973) using the 7th Orbiting Solar Observatory (OSO-7).

The largest geomagnetic perturbation, resulting presumably from a "prehistoric" CME, coincided with the first-observed solar flare, in 1859. The flare was observed visually by Richard Christopher Carrington and the geomagnetic storm was observed with the recording magnetograph at Kew Gardens.

When the ejecta reaches the Earth as an ICME (Interplanetary CME), it may disrupt the Earth's magnetosphere, compressing it on the dayside and extending the nightside tail. When the magnetosphere reconnects on the nightside, it creates trillions of watts of powerupper atmosphere. This process can cause particularly strong aurora also known as the Northern Lights, or aurora borealis (in the Northern Hemisphere), and the Southern Lights, or aurora australis (in the Southern Hemisphere). CME events, along with solar flares, can disrupt radio transmissions, cause power outages (blackouts), and cause damage to satellites and electrical transmission lines.