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Created page with "A '''coronal mass ejection''' (often abbreviated to CME) is a large outburst of plasma from the solar corona, the outermost layer of the Sun.<ref name=britannica>{..."
A '''coronal mass ejection''' (often abbreviated to CME) is a large outburst of [[plasma]] from the solar [[corona]], the outermost layer of the [[Sun]].<ref name=britannica>{{cite web|url=https://www.britannica.com/topic/coronal-mass-ejection|title=Coronal mass ejection|accessdate=2019-01-04}}</ref> These travel radially outwards from the Sun at [[speed]]s ranging from 250-3,000 km/s.<ref name=noaa>{{cite web|url=https://www.swpc.noaa.gov/phenomena/coronal-mass-ejections|title=CORONAL MASS EJECTIONS|accessdate=2019-01-5}}</ref> Coronal mass ejections can contain billions of tons of material and also possess an internal [[magnetic field]]. CMEs can be responsible for [[geomagnetic storm]]s on [[Earth]], which disturb the Earth's own magnetic field and may damage electronics.
The first observations of a CME were made using the OSO 7 [[satellite]] between 1971 and 1973.<ref name=spaceweatherlive>{{cite web|url=https://www.spaceweatherlive.com/en/help/what-is-a-coronal-mass-ejection-cme|title=What is a coronal mass ejection?|accessdate=2019-01-05}}</ref> The satellite utilised a coronagraph, a circular disk that blocks the bright light emanating from the Sun. This allows the much fainter solar corona and also CMEs to be observed.
==Physics and Properties==
Coronal mass ejections are believed to be formed when the [[Sun]]'s [[magnetic field]] suddenly reconfigures itself.<ref name=britannica/> High energy CMEs occur when the [[magnetic field|magnetic]] [[field line]]s in the Sun's [[corona]] become twisted and contorted.<ref name=noaa/> At some point the field becomes too stressed and this tension is released in a process called magnetic reconnection, where the field realigns. Sometimes there is a release of electromagnetic energy in the form of a [[solar flare]], followed by a burst of [[plasma]]. This plasma is the coronal mass ejection. Such ejections often occur where the magnetic field of the Sun is strong, such as near [[sunspot]]s. Alternatively, CMEs may be produced where comparatively cool but dense plasma is trapped by magnetic fields in the inner corona, known as solar filaments or [[prominences]].<ref name=noaa/> Sometimes this material will be simply reabsorbed into the solar surface when the magnetic fields reconfigure, but if not a CME may be generated.
CMEs are truly vast phenomena, with [[mass (science)|mass]] of 10<sup>15</sup> grams (billions of tons).<ref name=britannica/>. Travelling at 250-3,000 km/s a CMR may reach the Earth in anywhere from 15-18 hours to several days.<ref name=noaa/> As they travel outwards, the material that the ejection is composed of expands. When it reaches 1 [[AU]] from the Sun, it may be as large as 0.25 AU; a quarter of the distance between the [[Earth]] and the Sun.
==Effects on Earth==
If an ejection is directed towards the [[Earth]], it will generally result in a [[geomagnetic storm]] as well as vivid and very intense [[aurora]].<ref name=spaceweatherlive/> The energy of the CME can be transferred efficiently to the Earth by magnetic reconnection, the same process that originally generated the ejection.<ref name=britannica/>
==See also==
*[[Solar flare]]
*[[Sunspot]]
*[[Corona]]
*[[Sun]]
==References==
{{reflist}}
[[Category:Astronomy]]
[[Category:Stars]]
[[Category:Sun]]
The first observations of a CME were made using the OSO 7 [[satellite]] between 1971 and 1973.<ref name=spaceweatherlive>{{cite web|url=https://www.spaceweatherlive.com/en/help/what-is-a-coronal-mass-ejection-cme|title=What is a coronal mass ejection?|accessdate=2019-01-05}}</ref> The satellite utilised a coronagraph, a circular disk that blocks the bright light emanating from the Sun. This allows the much fainter solar corona and also CMEs to be observed.
==Physics and Properties==
Coronal mass ejections are believed to be formed when the [[Sun]]'s [[magnetic field]] suddenly reconfigures itself.<ref name=britannica/> High energy CMEs occur when the [[magnetic field|magnetic]] [[field line]]s in the Sun's [[corona]] become twisted and contorted.<ref name=noaa/> At some point the field becomes too stressed and this tension is released in a process called magnetic reconnection, where the field realigns. Sometimes there is a release of electromagnetic energy in the form of a [[solar flare]], followed by a burst of [[plasma]]. This plasma is the coronal mass ejection. Such ejections often occur where the magnetic field of the Sun is strong, such as near [[sunspot]]s. Alternatively, CMEs may be produced where comparatively cool but dense plasma is trapped by magnetic fields in the inner corona, known as solar filaments or [[prominences]].<ref name=noaa/> Sometimes this material will be simply reabsorbed into the solar surface when the magnetic fields reconfigure, but if not a CME may be generated.
CMEs are truly vast phenomena, with [[mass (science)|mass]] of 10<sup>15</sup> grams (billions of tons).<ref name=britannica/>. Travelling at 250-3,000 km/s a CMR may reach the Earth in anywhere from 15-18 hours to several days.<ref name=noaa/> As they travel outwards, the material that the ejection is composed of expands. When it reaches 1 [[AU]] from the Sun, it may be as large as 0.25 AU; a quarter of the distance between the [[Earth]] and the Sun.
==Effects on Earth==
If an ejection is directed towards the [[Earth]], it will generally result in a [[geomagnetic storm]] as well as vivid and very intense [[aurora]].<ref name=spaceweatherlive/> The energy of the CME can be transferred efficiently to the Earth by magnetic reconnection, the same process that originally generated the ejection.<ref name=britannica/>
==See also==
*[[Solar flare]]
*[[Sunspot]]
*[[Corona]]
*[[Sun]]
==References==
{{reflist}}
[[Category:Astronomy]]
[[Category:Stars]]
[[Category:Sun]]