A coronal mass ejection (CME) is a significant release of plasma and
magnetic field from the solar corona. They often follow solar flares
and are normally present during a solar prominence eruption. The
plasma is released into the solar wind, and can be observed in
Coronal mass ejections are often associated with other forms of solar
activity, but a broadly accepted theoretical understanding of these
relationships has not been established. CMEs most often originate from
active regions on the Sun's surface, such as groupings of sunspots
associated with frequent flares. Near solar maxima, the
1 Description 2 Cause 3 Impact on Earth 4 Physical properties 5 Association with other solar phenomena 6 Theoretical models 7 Interplanetary coronal mass ejections 8 Related solar observation missions
9.1 First traces 9.2 First clear detections 9.3 Recent events
10 Future risk 11 Stellar coronal mass ejections 12 See also 13 References 14 Further reading 15 External links
Follow a CME as it passes Venus then Earth, and explore how the Sun drives Earth's winds and oceans.
Arcs rise above an active region on the surface of the Sun.
Coronal mass ejections release large quantities of matter and
electromagnetic radiation into space above the Sun's surface, either
near the corona (sometimes called a solar prominence), or farther into
the planetary system, or beyond (interplanetary CME). The ejected
material is a magnetized plasma consisting primarily of electrons and
protons. While solar flares are very fast (being electromagnetic
radiation), CMEs are relatively slow.
Coronal mass ejections are associated with enormous changes and
disturbances in the coronal magnetic field. They are usually observed
with a white-light coronagraph.
Scientific research has shown that the phenomenon of magnetic
reconnection is closely associated with CMEs and solar flares. In
magnetohydrodynamic theory, the sudden rearrangement of magnetic field
lines when two oppositely directed magnetic fields are brought
together is called "magnetic reconnection". Reconnection releases
energy stored in the original stressed magnetic fields. These magnetic
field lines can become twisted in a helical structure, with a
'right-hand twist' or a 'left hand twist'. As the Sun's magnetic field
lines become more and more twisted, CMEs appear to be a 'valve' to
release the magnetic energy being built up, as evidenced by the
helical structure of CMEs, that would otherwise renew itself
continuously each solar cycle and eventually rip the
Impact on Earth
When the ejection is directed towards
A video of the series of CMEs in August 2010.
This video features two model runs. One looks at a moderate coronal mass ejection (CME) from 2006. The second run examines the consequences of a large coronal mass ejection, such as the Carrington-class CME of 1859.
A typical coronal mass ejection may have any or all of three
distinctive features: a cavity of low electron density, a dense core
(the prominence, which appears on coronagraph images as a bright
region embedded in this cavity), and a bright leading edge.
Most ejections originate from active regions on the Sun's surface,
such as groupings of sunspots associated with frequent flares. These
regions have closed magnetic field lines, in which the magnetic field
strength is large enough to contain the plasma. These field lines must
be broken or weakened for the ejection to escape from the Sun.
However, CMEs may also be initiated in quiet surface regions, although
in many cases the quiet region was recently active. During solar
minimum, CMEs form primarily in the coronal streamer belt near the
solar magnetic equator. During solar maximum, they originate from
active regions whose latitudinal distribution is more homogeneous.
Coronal mass ejections reach velocities from 20 to 3,200 km/s (12
to 1,988 mi/s) with an average speed of 489 km/s
(304 mi/s), based on SOHO/LASCO measurements between 1996 and
2003. These speeds correspond to transit times from the
Video of a solar filament being launched
Coronal mass ejections are often associated with other forms of solar activity, most notably:
Eruptive prominence and
The association of a CME with some of those phenomena is common but not fully understood. For example, CMEs and flares are normally closely related, but there was confusion about this point caused by the events originating beyond the limb. For such events no flare could be detected. Most weak flares do not have associated CMEs; most powerful ones do. Some CMEs occur without any flare-like manifestation, but these are the weaker and slower ones. It is now thought that CMEs and associated flares are caused by a common event (the CME peak acceleration and the flare impulsive phase generally coincide). In general, all of these events (including the CME) are thought to be the result of a large-scale restructuring of the magnetic field; the presence or absence of a CME during one of these restructures would reflect the coronal environment of the process (i.e., can the eruption be confined by overlying magnetic structure, or will it simply break through and enter the solar wind). Theoretical models It was first postulated that CMEs might be driven by the heat of an explosive flare. However, it soon became apparent that many CMEs were not associated with flares, and that even those that were often started before the flare. Because CMEs are initiated in the solar corona (which is dominated by magnetic energy), their energy source must be magnetic. Because the energy of CMEs is so high, it is unlikely that their energy could be directly driven by emerging magnetic fields in the photosphere (although this is still a possibility). Therefore, most models of CMEs assume that the energy is stored up in the coronal magnetic field over a long period of time and then suddenly released by some instability or a loss of equilibrium in the field. There is still no consensus on which of these release mechanisms is correct, and observations are not currently able to constrain these models very well. These same considerations apply equally well to solar flares, but the observable signatures of these phenomena differ. Interplanetary coronal mass ejections
Illustration of a coronal mass ejection moving beyond the planets toward the heliopause
CMEs typically reach
Forbush decrease Health threat from cosmic rays K-index List of coronal mass ejections List of solar storms Magnetic cloud Orbiting Solar Observatory Solar and Heliospheric Observatory Space weather
^ Christian, Eric R. (5 March 2012). "Coronal Mass Ejections".
NASA/Goddard Space Flight Center. Retrieved 9 July 2013.
^ Hathaway, David H. (14 August 2014). "Coronal Mass Ejections".
NASA/Marshall Space Flight Center. Retrieved 7 July 2016.
^ "Coronal Mass Ejections". NOAA/Space Weather Prediction Center.
Retrieved 7 July 2016.
^ Fox, Nicky. "Coronal Mass Ejections". NASA/International
Solar-Terrestrial Physics. Retrieved 6 April 2011.
^ Gleber, Max (21 September 2014). "CME Week: The Difference Between
Flares and CMEs". NASA. Retrieved 7 July 2016.
^ "Scientists unlock the secrets of exploding plasma clouds on the
sun". Eurekalert.org. American Physical Society. 8 November 2010.
Retrieved 7 July 2016.
^ Phillips, Tony, ed. (1 March 2001). "Cannibal Coronal Mass
Ejections". Science News. NASA. Retrieved 20 March 2015.
^ Green, Lucie (2014). 15 Million Degrees. Viking. p. 212.
^ Holman, Gordon D. (April 2006). "The Mysterious Origins of Solar
Flares". Scientific American. 294 (4): 38–45.
^ Baker, Daniel N.; et al. (2008). Severe Space Weather Events —
Understanding Societal and Economic Impacts: A Workshop Report.
National Academies Press. p. 77. doi:10.17226/12507.
ISBN 978-0-309-12769-1. These assessments indicate that severe
geomagnetic storms pose a risk for long-term outages to major portions
of the North American grid. John Kappenman remarked that the analysis
shows "not only the potential for large-scale blackouts but, more
troubling, ... the potential for permanent damage that could lead to
extraordinarily long restoration times."
^ a b Morring, Jr., Frank (14 January 2013). "Major Solar Event Could
Devastate Power Grid". Aviation Week & Space Technology.
pp. 49–50. But the most serious potential for damage rests with
the transformers that maintain the proper voltage for efficient
transmission of electricity through the grid.
^ Wilson, John W.; Wood, J. S.; Shinn, Judy L.; Cucinotta, Francis A.;
Nealy, John E. (August 1993). "A proposed performance index for
galactic cosmic ray shielding materials". NASA.
Bibcode:1993STIN...9411278W. Technical Manual 4444.
^ Carroll, Bradley W.; Ostlie, Dale A. (2007). An Introduction to
Modern Astrophysics. San Francisco: Addison-Wesley. p. 390.
^ Tomczak, M.; Chmielewska, E. (March 2012). "A Catalog of Solar X-Ray
Plasma Ejections Observed by the Soft X-Ray Telescope on Board
The Astrophysical Journal Supplement Series. 199 (1). 10.
arXiv:1201.1040 . Bibcode:2012ApJS..199...10T.
^ Andrews, M. D. (December 2003). "A Search for CMEs Associated with
Big Flares". Solar Physics. 218 (1): 261–279.
^ Manoharan, P. K. (May 2006). "Evolution of Coronal Mass Ejections in
the Inner Heliosphere: A Study Using White-Light and Scintillation
Images". Solar Physics. 235 (1-2): 345–368.
^ Freiherr von Forstner, Johan L.; Guo, Jingnan; Wimmer-Schweingruber,
Robert F.; et al. (2017). "Using Forbush decreases to derive the
transit time of ICMEs propagating from 1 AU to Mars". Journal of
Geophysical Research: Space Physics: 2017JA024700.
arXiv:1712.07301 . doi:10.1002/2017ja024700.
^ Richardson, I. G. (2014). "Identification of Interplanetary Coronal
Mass Ejections at Ulysses Using Multiple Solar Wind Signatures". Solar
Physics. 289 (10): 3843–3894. Bibcode:2014SoPh..289.3843R.
doi:10.1007/s11207-014-0540-8. ISSN 0038-0938.
^ Wilkinson, John (2012). New Eyes on the Sun: A Guide to Satellite
Images and Amateur Observation. Springer. p. 98.
^ Vourlidas, A.; Wu, S. T.; Wang, A. H.; Subramanian, P.; Howard, R.
A. (December 2003). "Direct Detection of a Coronal Mass
Ejection-Associated Shock in Large Angle and Spectrometric Coronagraph
Experiment White-Light Images". The Astrophysical Journal. 598 (2):
1392–1402. arXiv:astro-ph/0308367 . Bibcode:2003ApJ...598.1392V.
^ Manchester, W. B., IV; Gombosi, T. I.; De Zeeuw, D. L.; Sokolov, I.
V.; Roussev, I. I.; et al. (April 2005). "Coronal Mass Ejection Shock
and Sheath Structures Relevant to Particle Acceleration" (PDF). The
Astrophysical Journal. 622 (2): 1225–1239.
Bibcode:2005ApJ...622.1225M. doi:10.1086/427768. Archived from the
original (PDF) on 5 February 2007.
^ "Spacecraft go to film
Nicholson, Seth B. (1954). "Solar Activity in 1953". Publications of the Astronomical Society of the Pacific. 66 (389): 55–57. Bibcode:1954PASP...66...55N. doi:10.1086/126653. ISSN 0004-6280. JSTOR 40672795. Cragg, Thomas A. (1955). "Solar Activity in 1954". Publications of the Astronomical Society of the Pacific. 67 (395): 99–101. Bibcode:1955PASP...67...99C. doi:10.1086/126771. ISSN 0004-6280. JSTOR 40672921. Nicholson, Seth B. (1956). "Solar Activity in 1955". Publications of the Astronomical Society of the Pacific. 68 (401): 146–148. Bibcode:1956PASP...68..146N. doi:10.1086/126899. ISSN 0004-6280. JSTOR 40673035. Cragg, Thomas A. (1957). "Solar Activity in 1956". Publications of the Astronomical Society of the Pacific. 69 (407): 166–168. Bibcode:1957PASP...69..166C. doi:10.1086/127038. ISSN 0004-6280. JSTOR 40676393. Cragg, Thomas A. (1958). "Solar Activity in 1957". Publications of the Astronomical Society of the Pacific. 70 (414): 299–302. Bibcode:1958PASP...70..299C. doi:10.1086/127227. ISSN 0004-6280. JSTOR 40673342. Cragg, Thomas A. (1959). "Solar Activity in 1958". Publications of the Astronomical Society of the Pacific. 71 (420): 212–215. Bibcode:1959PASP...71..212C. doi:10.1086/127366. ISSN 0004-6280. JSTOR 40673498. Cragg, Thomas A. (1960). "Solar Activity in 1959". Publications of the Astronomical Society of the Pacific. 72 (426): 200–203. Bibcode:1960PASP...72..200C. doi:10.1086/127509. ISSN 0004-6280. JSTOR 40676961. Cragg, Thomas A. (1961). "Solar Activity in 1960". Publications of the Astronomical Society of the Pacific. 73 (432): 198–201. Bibcode:1961PASP...73..198C. doi:10.1086/127655. ISSN 0004-6280. JSTOR 40673546.
^ Howard, Russell A. (October 2006). "A Historical Perspective on
Coronal Mass Ejections" (PDF). Solar Eruptions and Energetic
Particles. Geophysical Monograph Series. 165. American Geophysical
Union. Bibcode:2006GMS...165....7H. doi:10.1029/165GM03.
^ Howard, Russell A. (1999). "Obituary: Guenter E. Brueckner,
1934-1998". Bulletin of the American Astronomical Society. 31 (5):
^ a b Phillips, Tony (23 July 2014). "Near Miss: The Solar Superstorm
of July 2012". NASA. Retrieved 26 July 2014.
^ "ScienceCasts: Carrington-class CME Narrowly Misses Earth".
YouTube.com. NASA. 28 April 2014. Retrieved 26 July 2014.
^ "NASA's SDO Sees Massive Filament Erupt on Sun". NASA. 4 September
2012. Retrieved 11 September 2012.
^ "August 31, 2012 Magnificent CME". NASA/Goddard Space Flight Center.
31 August 2012. Retrieved 11 September 2012.
^ "Space Weather Alerts and Warnings Timeline: September 1–16, 2012
(archive)". NOAA. Archived from the original on 28 September 2012.
Retrieved 24 September 2012.
^ Chillymanjaro (6 September 2012). "Geomagnetic storming levels back
to normal". The Watchers. Retrieved 11 September 2012.
^ Witasse, O.; Sánchez-Cano, B.; Mays, M. L.; Kajdič, P.;
Opgenoorth, H.; et al. (14 August 2017). "Interplanetary coronal mass
ejection observed at STEREO-A, Mars, comet 67P/Churyumov-Gerasimenko,
Gopalswamy, Natchimuthukonar; Mewaldt, Richard A.; Torsti, Jarmo, eds. (October 2006). Solar Eruptions and Energetic Particles. Geophysical Monograph Series. 165. American Geophysical Union. Bibcode:2006GMS...165.....G. doi:10.1029/GM165. ISBN 0-87590-430-0.
Bell, Trudy E.; Phillips, Tony (6 May 2008). "A Super Solar Flare".
Phillips, Tony (27 May 2008). "Cartwheel Coronal Mass Ejection".
Odenwald, Sten F.; Green, James L. (28 July 2008). "Bracing the
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