In addition to these relatively stable features, there are many events which represent a rapid (minutes to hours) release of energy. These include flares, coronal mass ejections, eruptive prominences, proton events, and solar radio noise. All of these events influence the Earth's upper atmosphere and are particularly harmful to humans and equipment in Earth orbit.
Many of these events, which arise from the solar atmosphere, are due to a sudden reconfiguration of the large-scale magnetic field of the Sun, in which magnetic energy is converted to mechanical energy, leading to an ejection of material from the Sun, usually toward Earth. In this process, charged particles (electrons and ionized atoms) also contribute to bursts of emission in X-rays, radio waves and gamma-rays. Many of these effects are crippling for radio communication and satellite systems.
Some of the solar eruptions are on very large scales, such as those associated with coronal mass ejections (CMEs), which can be as large as half of the solar radius. Disturbances in the magnetic field of the Earth are also a direct result of changes in the Sun's large-scale field.
Approved by Peter Fox
Last revised: Wed May 17 11:28:21 MDT 2000