View source for User:Marshallsumter/Radiation astronomy1/Magnetism

[[Image:Media 1.ogv|thumb|right|250px|On July 19, 2012, an eruption occurred on the sun that produced a moderately powerful solar flare and a dazzling magnetic display known as coronal rain. Credit: NASA Goddard Space Flight Center, Music: 'Thunderbolt' by Lars Leonhard, courtesy of artist.]]
A [[coronal cloud]] is a cloud, or cloud-like, natural astronomical entity, composed of plasma and usually associated with a star or other astronomical object where the temperature is such that X-rays are emitted. While small coronal clouds are above the photosphere of many different visual spectral type stars, others occupy parts of the [[interstellar medium]] (ISM), extending sometimes millions of kilometers into space, or thousands of light-years, depending on the size of the associated object such as a galaxy.
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==Neutrals==
{{main|Radiation astronomy/Neutrals|Neutrals astronomy}}
[[Image:Image-Pegasus XL IBEX in clean room 02.jpg|thumb|right|250px|This image shows the IBEX (photo cells forward) being surrounded by its protective nose cone. Credit: NASA (John F. Kennedy Space Center).{{tlx|free media}}]]
[[Image:Gruntman ena 01.jpg|thumb|right|250px|A hot plasma ion 'steals' charge from a cold neutral atom to become an '''E'''nergetic '''N'''eutral '''A'''tom ('''ENA''').<ref name=GrunDiagram>{{ cite web
|title= Charge Exchange Diagrams, In: ''Energetic Neutral Atoms Tutorial''
| author=Mike Gruntman
| url=http://astronauticsnow.com/ENA/index.html
| accessdate=2009-10-27 }}</ref> Credit Mike Gruntman.{{tlx|free media}}]]
[[Image:Gruntman ena 02.jpg|thumb|right|250px |The ENA leaves the charge exchange in a straight line with the velocity of the original plasma ion.<ref name=GrunDiagram/> Credit: Mike Gruntman.{{tlx|free media}}]]
[[Image:484684main 1 AP IBEX combined 1.74.jpg|thumb|right|250px|This image is an all-sky map of neutral atoms streaming in from the interstellar boundary. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio.{{tlx|free media}}]]
"The sensors on the IBEX spacecraft are able to detect energetic neutral atoms (ENAs) at a variety of energy levels."<ref name=McComas>{{ cite book
|author=Dave McComas
|author2=Lindsay Bartolone
|title=IBEX: Interstellar Boundary Explorer
|publisher=NASA Southwest Research Institute
|location=San Antonio, Texas USA
|date=May 10, 2012
|url=http://ibex.swri.edu/mission/measurements.shtml
|accessdate=2012-08-11 }}</ref>

The satellite's payload consists of two energetic neutral atom (ENA) imagers, IBEX-Hi and IBEX-Lo. Each of these sensors consists of a collimator that limits their fields-of-view, a conversion surface to convert neutral hydrogen and oxygen into ions, an electrostatic analyzer (ESA) to suppress ultraviolet light and to select ions of a specific energy range, and a detector to count particles and identify the type of each ion.

"IBEX–Lo can detect particles with energies ranging from 10 electron–volts to 2,000 electron–volts (0.01 keV to 2 keV) in 8 separate energy bands. IBEX–Hi can detect particles with energies ranging from 300 electron–volts to 6,000 electron–volts (.3 keV to 6 keV) in 6 separate energy bands. ... Looking across the entire sky, interactions occurring at the edge of our Solar System produce ENAs at different energy levels and in different amounts, depending on the process."<ref name=McComas/>

Proton–hydrogen charge-exchange collisions [such as those shown at right] are often the most important process in space plasma because [h]ydrogen is the most abundant constituent of both plasmas and background gases and hydrogen charge-exchange occurs at very high velocities involving little exchange of momentum.

"Energetic neutral atoms (ENA), emitted from the magnetosphere with energies of ∼50 keV, have been measured with solid-state detectors on the IMP 7/8 and ISEE 1 spacecraft. The ENA are produced when singly charged trapped ions collide with the exospheric neutral hydrogen geocorona and the energetic ions are neutralized by charge exchange."<ref name=Roelof>{{ cite journal
|author=E. C. Roelof
|author2=D. G. Mitchell
|author3=D. J. Williams
|title=Energetic neutral atoms (E ∼ 50 keV) from the ring current: IMP 7/8 and ISEE 1
|journal=Journal of Geophysical Research
|month=
|year=1985
|volume=90
|issue=A11
|pages=10,991-11,008
|url=http://www.agu.org/pubs/crossref/1985/JA090iA11p10991.shtml
|arxiv=
|bibcode=
|doi=10.1029/JA090iA11p10991
|pmid=
|accessdate=2012-08-12 }}</ref>

"The IMAGE mission ... High Energy Neutral Atom imager (HENA) ... images [ENAs] at energies between 10 and 60 keV/nucleon [to] reveal the distribution and the evolution of energetic [ions, including protons] as they are injected into the ring current during geomagnetic storms, drift about the Earth on both open and closed drift paths, and decay through charge exchange to pre‐storm levels."<ref name=Mitchell>{{ cite journal
|author=D. G. Mitchell
|author2=K. C. Hsieh
|author3=C. C. Curtis
|author4=D. C. Hamilton
|author5=H. D. Voes
|author6=E. C Roelof
|author7=P. C:son-Brandt
|title=Imaging two geomagnetic storms in energetic neutral atoms
|journal=Geophysical Research Letters
|month=
|year=2001
|volume=28
|issue=6
|pages=1151-4
|url=http://www.agu.org/pubs/crossref/2001/2000GL012395.shtml
|arxiv=
|bibcode=
|doi=10.1029/2000GL012395
|pmid=
|accessdate=2012-08-12 }}</ref>

"In 2009, NASA's Interstellar Boundary Explorer (IBEX) mission science team constructed the first-ever all-sky map [at right] of the interactions occurring at the edge of the solar system, where the sun's influence diminishes and interacts with the interstellar medium. A 2013 paper provides a new explanation for a giant ribbon of energetic neutral atoms – shown here in light green and blue --  streaming in from that boundary."<ref name=Fox>{{ cite web
|author=Karen C. Fox
|title=A Major Step Forward in Explaining the Ribbon in Space Discovered by NASA’s IBEX Mission
|publisher=NASA's Goddard Space Flight Center
|location=Greenbelt, MD USA
|date=February 5, 2013
|url=http://www.nasa.gov/mission_pages/ibex/news/ribbon-explained.html
|accessdate=2013-02-06 }}</ref>

"[T]he boundary at the edge of our heliosphere where material streaming out from the sun interacts with the galactic material ... emits no light and no conventional telescope can see it. However, particles from inside the solar system bounce off this boundary and neutral atoms from that collision stream inward. Those particles can be observed by instruments on NASA’s Interstellar Boundary Explorer (IBEX). Since those atoms act as fingerprints for the boundary from which they came, IBEX can map that boundary in a way never before done. In 2009, IBEX saw something in that map that no one could explain: a vast ribbon dancing across this boundary that produced many more energetic neutral atoms than the surrounding areas."<ref name=Fox/>

""What we are learning with IBEX is that the interaction between the sun's magnetic fields and the galactic magnetic field is much more complicated than we previously thought," says Eric Christian, the mission scientist for IBEX at NASA's Goddard Space Flight Center in Greenbelt, Md. "By modifying an earlier model, this paper provides the best explanation so far for the ribbon IBEX is seeing.""<ref name=Fox/>
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==Protons==
{{main|Radiation astronomy/Protons}}

"The ‘bubble’ of solar wind plasma and frozen-in magnetic fields expanding out from the solar corona, within a few radii of the Sun, to boundaries with the local interstellar gas and plasma near about 100 AU is called the heliosphere. Dependent on points of origin at the Sun, and on time phase during the eleven year cycle of solar activity, the solar wind plasma expands radially outward at speeds of 300–800 km/s. Neutral atoms flowing into the heliosphere from the Very Local Interstellar Medium (VLISM) can be ionized by solar UV, and by charge exchange with solar wind ions, then picked up by magnetic fields in the outward plasma flow. Due to inverse-square fall-off of solar wind ion density with distance from the Sun, these interstellar pickup ions increasingly contribute to the plasma pressure and become the dominant component beyond the orbit of Saturn (Burlaga et al., 1996; Whang et al., 1996). Further out near 90–100 AU (Stone, 2001; Stone and Cummings, 2001; Whang and Burlaga, 2002) the outflowing plasma is expected to encounter the solar wind termination shock where flow speeds abruptly transition to sub-sonic values ∼100 km/s. The shock position is dependent in part on the plasma and neutral gas density in the Local Interstellar Medium (LISM) and could move into the giant planet region, or even nearer to the Earth’s orbit, if the Sun passed through a region of much higher LISM density (Zank and Frisch, 1999; Frisch, 2000). Further out at 120 AU or more should be the heliopause, the contact boundary between the diverted solar wind plasma flows and the in-flowing interstellar plasma. The intervening region between the termination shock and the heliopause is called the heliosheath. In this latter region the previously radial flow of the solar wind is diverted into a direction downstream from the ∼26 km/s flow of the interstellar gas to form a huge teardrop-shaped structure called the heliotail which extends hundreds to perhaps thousands of AU from the Sun into the VLISM."<ref name=Cooper>{{ cite book
|author=John F. Cooper
|author2=Eric R. Christian
|author3=John D. Richardson
|author4=Chi Wang
|title=Proton irradiation of Centaur, Kuiper Belt, and Oort Cloud objects at plasma to cosmic ray energy, In: ''The First Decadal Review of the Edgeworth-Kuiper Belt''
|date=2004
|pages=261-277
|volume=92
|editor=Davies J.K., Barrera L.H.
|publisher=Springer
|location=Dordrecht
|url=http://people.virginia.edu/~rej/papers06/Cooper2003EMP20040616.pdf
|arxiv=
|bibcode=
|doi=10.1007/978-94-017-3321-2_24
|pmid=
|accessdate=19 June 2019 }}</ref>

"The initial solar wind conditions at the inner boundary at 1 AU are radial outward speed V = 441 km/s, solar wind proton density N = 7.0/cc and temperature T = 9.8 × 10<sup>4</sup> K, and interplanetary magnetic field = 7.0 × 10<sup>−5</sup> Gauss. The interstellar hydrogen atoms at the solar wind termination shock are taken to have speed 20 km/s and temperature 1 × 10<sup>4</sup> K, while H<sup>0</sup> density, and the energy partition ratio for ions, are varied to give good fits to radial speed and temperature profiles measured by the operational plasma spectrometer on Voyager 2. Good fits are obtained for a neutral density of 0.09/cc and a partition ratio of 0.05, which means that five percent of the total energy from the pickup process goes into solar wind protons. For the LISM plasma ions, which are not included in the Wang and Richardson model, we compute convecting maxwellian (Vasyliunas, 1971) distributions for the LISM parameters T ∼ 7000 K, u ∼ 26 km/s, and N ∼ 0.1/cc of interstellar protons as derived from Wood and Linsky (1997)."<ref name=Cooper/>

"Near solar minimum the ACR ions, including protons, are dominant components of radiation dosage outward from ∼40 AU to the outer heliosphere, while these ions largely disappear at solar maximum. There is a 22-year cycle in the polarity of the solar dipole magnetic field, which is frozen into the solar wind plasma within several radii of the Sun and thereby carried outward into the heliosphere. Due to sign-dependent transport effects, the ACR ions accelerated at the termination shock have larger fluxes, and more positive radial gradients, at 40 to 85 AU near the Ecliptic when the solar dipole moment is directed southward (qA < 0 polarity) than when it is northward (qA > 0 polarity)."<ref name=Cooper/>

==Ultraviolets==
{{main|Radiation astronomy/Ultraviolets|Ultraviolet astronomy}}
[[Image:August 2010 CME SDO.jpg|thumb|right|200px|A coronal mass ejection is shown in the ultraviolet. Credit: NASA/SDO.]]
[[Image:STEREO B EUVI 171.jpg|thumb|left|250px|The chromosphere of the Sun shows in ultraviolets. Credit: STEREO (NASA).]]
"One of the fastest CMEs in years was captured by the STEREO COR1 telescopes on August 1, 2010. ... This CME is seen to be heading towards Earth at speeds well over 1000 kilometers per second."<ref name=Zell/>

"On August 1st, almost the entire Earth-facing side of the sun erupted in a tumult of activity. There was a C3-class solar flare, a solar tsunami, multiple filaments of magnetism lifting off the stellar surface, large-scale shaking of the solar corona, radio bursts, a coronal mass ejection and more. This extreme ultraviolet snapshot [at right] from the Solar Dynamics Observatory (SDO) shows the sun's northern hemisphere in mid-eruption. Different colors in the image represent different gas temperatures ranging from ~1 to 2 million degrees K."<ref name=Zell>{{ cite book
|author=Holly Zell
|title=Spacecraft Observes Coronal Mass Ejection
|publisher=NASA
|location=Washington, DC USA
|date=August 4, 2010
|url=http://www.nasa.gov/topics/solarsystem/sunearthsystem/main/News080210-cme.html
|accessdate=2013-07-07 }}</ref>
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==Magnetism==
[[Image:Mineral magnetite (lodestone), from Tortola, British Virgin Islands.jpg|right|thumb|250px|Mineral magnetite (lodestone), from Tortola, British Virgin Islands is magnetic. Credit: [[c:User:Chris Oxford|Chris Oxford]].{{tlx|free media}}]]
'''Def.''' a mineral that is weakly attracted by the poles of a magnet but does not retain any permanent magnetism is called a '''paramagnet''', or a '''paramagnetic mineral'''.

'''Def.''' a mineral that is weakly attracted by the poles of a magnet tending to become magnetized in a direction at 180° to the applied magnetic field but does not retain any permanent magnetism is called a '''diamagnet''', or a '''diamagnetic mineral'''.

'''Def.''' a mineral that is exhibits the poles of a magnet even in zero applied magnetic field is called a '''ferromagnet''', or a '''ferromagnetic mineral'''.

'''Def.''' a mineral that is exhibits the poles of a magnet even in zero applied magnetic field but with opposite directions is called a '''antiferromagnet''', or a '''antiferromagnetic mineral'''.

'''Def.''' a mineral that is exhibits the poles of a magnet even in zero applied magnetic field with opposite directions but a net magnetic moment is called a '''ferrimagnet''', or a '''ferrimagnetic mineral'''.
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==Alloys==

Antitaenite is a meteoritic metal alloy mineral composed of iron and nickel, 20-40% Ni (and traces of other chemical elements) that has a face centered cubic crystal structure that exists as a new mineral species occurring in both iron meteorites and in chondrites<ref>D.G. Rancourt and R.B. Scorzelli. Low Spin γ-Fe-Ni (γLS) Proposed as a New Mineral in Fe-Ni-Bearing Meteorites: Epitaxial Intergrowth of γLS and Tetrataenite as Possible Equilibrium State at ~20-40 at % Ni. Journal of Magnetism and Magnetic Materials 150 (1995) 30-36</ref> The pair of minerals antitaenite and taenite constitute the first example in nature of two minerals that have the same crystal structure (face centered cubic) have the same chemical composition (same proportions of Fe and Ni) - but differ in their electronic structures: taenite has a high magnetic moment whereas antitaenite has a low magnetic moment.<ref>D.G. Rancourt, K. Lagarec, A. Densmore, R.A. Dunlap, J.I. Goldstein, R.J. Reisener, and R.B. Scorzelli. Experimental Proof of the Distinct Electronic Structure of a New Meteoritic Fe-Ni Alloy Phase. Journal of Magnetism and Magnetic Materials 191 (1999) L255-L260</ref> This difference arises from a high-magnetic-moment to low-magnetic-moment transition occurring in the Fe-Ni bi-metallic alloy series.<ref>K. Lagarec, D.G. Rancourt, S.K. Bose, B. Sanyal, and R.A. Dunlap. Observation of a composition-controlled high-moment/low-moment transition in the face centered cubic Fe-Ni system: Invar effect is an expansion, not a contraction. Journal of Magnetism and Magnetic Materials 236 (2001) 107-130.</ref>

Taenite (Fe,Ni), an alloy of iron and nickel, with nickel proportions of 20% up to 65%, found naturally on [[Rocks/Rocky objects/Earth|Earth]] mostly in iron meteorites, one of four known Fe-Ni meteorite minerals: kamacite, taenite, tetrataenite, and antitaenite, that is opaque with a metallic grayish to white color, has an isometric-hexoctahedral structure, a density around 8 g/cm³ and a hardness 5 to 5.5 on the Mohs scale of mineral hardness (Mohs scale) that is magnetic, with a crystal lattice of the c≈a= 3.582 Å ± 0.002 Å.<ref>{{cite journal
|title=Structure of taenite in two iron meteorites J.
|first1=F.
|last1=Albertsen
|first2=J. M.
|last2=Knudsen
|first3=G. B.
|last3=Jensen
|journal=Nature
|volume=273
|pages=453–454
|date=Jun
|year=1978
|doi=10.1038/273453a0
|issue=5662
|bibcode = 1978Natur.273..453A }}</ref> The Strunz classification is I/A.08-20, while the Dana classification is 1.1.11.2, with a hexoctahedral (cubic) structure.

==Iron meteorites==
[[Image:Iron-meteorite-impact-craters.png|thumb|right|250px|This iron meteorite also left no impact crater in the desert. Credit: Geuology.com.]]
As indicated in the image on the right, all or nearly all, iron meteorites are magnetic. Passage through the Earth's magnetic field and the natural electric field of the Earth may cause these iron meteorites to slow down sufficiently so as to land without a crater.
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==Solar magnetic active regions==
[[Image:Sun STEREO 4dec2006 lrg.jpg|thumb|right|200px|The false color image shows a number of bright magnetic active regions on the Sun. Credit: NASA.{{tlx|free media}}]]
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==Sunquakes==
[[Image:MoretonWaveAnimation200612.gif|thumb|right|250px|This is an animation of a Moreton wave which occurred on the Sun at December 6, 2006. Credit: National Solar Observatory (NSO)/AURA/NSF and USAF Research Laboratory.]]
[[Image:Solar tsunami.jpg|thumb|250px|right|This image shows a solar tsunami on May 19, 2007. Credit: NASA/STEREO/EUVI consortium.]]
"The phenomenon of flare induced sunquakes - waves in the photosphere - discovered by Kosovichev and Zharkova (1998) and now widely studied (e.g. Kosovichev 2006) should also result from the momentum impulse delivered by a cometary impact."<ref name=Brown>{{ cite journal
|author=J.C. Brown
|author2=H.E. Potts
|author3=L.J. Porter
|author4=G.le Chat
|title=Mass Loss, Destruction and Detection of Sun-grazing & -impacting Cometary Nuclei
|journal=Astronomy & Astrophysics
|date=November 8, 2011
|volume=535
|issue=
|pages=12
|url=http://www.aanda.org/articles/aa/abs/2011/11/aa15660-10/aa15660-10.html
|arxiv=
|bibcode=
|doi=10.1051/0004-6361/201015660
|pmid=
|pdf=http://arxiv.org/pdf/1107.1857.pdf
|accessdate=2012-11-25 }}</ref>

A '''Moreton wave''' is the [[w:chromosphere|chromospheric]] signature of a large-scale solar [[Coronal cloud|coronal]] [[w:shock wave|shock wave]]. Described as a kind of [[Stars/Sun|solar]] '[[w:tsunami|tsunami]]',<ref name="tphill09">{{ cite book
|author=Tony Phillips
|title=Monster Waves on the Sun are Real
|url=http://science.nasa.gov/science-news/science-at-nasa/2009/24nov_solartsunami/
|publisher=NASA
|accessdate=16 July 2010
|date=November 24, 2009 }}</ref> they are generated by solar flares<ref name=Moreton>{{ cite journal
|author=G. E. Moreton
|title=Hα Observations of Flare-Initiated Disturbances with Velocities ~1000 km/sec
|journal=Astronomical Journal
|volume=65
|issue=
|pages=494
|year=1960
|doi=10.1086/108346
|bibcode=1960AJ.....65U.494M }}</ref><ref name=Moreton60>{{ cite journal
|author=G. E. Moreton, H. E. Ramsey
|title=Recent Observations of Dynamical Phenomena Associated with Solar Flares
|journal=Publications of the Astronomical Society of the Pacific
|volume=72
|issue=428
|pages=357
|year=1960
|doi=10.1086/127549
|bibcode=1960PASP...72..357M }}</ref><ref name=Athay61>{{ cite journal
|author=R. Grant Athay, Gail E. Moreton
|title=Impulsive Phenomena of the Solar Atmosphere. I. Some Optical Events Associated with Flares Showing Explosive Phase
|journal=The Astrophysical Journal
|year=1961
|volume=133
|issue=
|pages=935
|doi=10.1086/147098
|bibcode=1961ApJ...133..935A }}</ref>.

The 1995 launch of the [[w:Solar and Heliospheric Observatory|Solar and Heliospheric Observatory]] led to observation of coronal waves, which cause Moreton waves. (SOHO's [[w:Extreme ultraviolet Imaging Telescope|EIT]] instrument discovered another, different wave type called 'EIT waves'.)<ref name=Chen>{{ cite journal
|url=http://solar.physics.montana.edu/nuggets/2002/020208/020208.html
|title=Moreton waves and coronal waves
|journal=The Astrophysical Journal
|volume=572
|issue=
|pages=L99–L102
|year=2002
|bibcode = 2002ApJ...572L..99C
|doi = 10.1086/341486
|author=P. F. Chen
|author2=S. T. Wu
|author3=K. Shibata
|author4=C. Fang
}}</ref> The reality of Moreton waves (aka fast-mode [[w:Magnetohydrodynamics|MHD]] waves) has also been confirmed by the two [[w:STEREO|STEREO]] spacecraft. They observed a 100,000-km-high wave of hot plasma and magnetism, moving at 250&nbsp;km/second, in conjunction with a big coronal mass ejection in February 2009.<ref name=Atkins>{{ cite book
|author=William Atkins
|title=STEREO spacecraft finds gigantic tsunami on Sun
|url=http://www.itwire.com/science-news/space/29658-stereo-spacecraft-finds-gigantic-tsunami-on-sun
|publisher=iTWire
|accessdate=16 July 2010
|date=26 November 2009 }}</ref><ref name="pho111909">{{ cite book
|title=Mystery of the Solar Tsunami -- Solved
|url=http://www.physorg.com/news177872248.html
|publisher=PhysOrg.com
|accessdate=16 July 2010
|author=JPL/NASA
|date=November 19, 2009 }}</ref>

Moreton waves propagate at a speed of usually 500–1500&nbsp;km/s. [[w:Yutaka Uchida|Yutaka Uchida]] interpreted Moreton waves as MHD fast mode shock waves propagating in the corona.<ref name=Sakurai2002>{{ cite book
|author=Takashi Sakurai
|title=SolarNews Newsletter
|url=http://spd.aas.org/SolarNews/archive/news.2002/19.sep
|publisher=Solar Physics Division, American Astronomical Society
|accessdate=15 June 2011
|date=3 September 2002 }}</ref> He links them to [[w:type II radio bursts|type II radio bursts]], which are radio wave discharges created when coronal mass ejections accelerate shocks.<ref name=Layton>{{ cite book
|author=Laura Layton
|title=STEREO Spies First Major Activity of Solar Cycle 24
|url=http://www.nasa.gov/mission_pages/stereo/news/solarcycle24.html
|publisher=NASA
|accessdate=15 June 2011
|date=May 15, 2009 }}</ref>

Moreton waves can be observed primarily in the [[w:Hα|Hα]] band.<ref name="Narukage, et al.">{{ cite journal
|author=N. Narukage
|author2=Shigeru
|author3=Miwako Kadota
|author4=Reizaburo Kitai
|author5=Hiroki Kurokawa
|author6=Kazunari Shibata
|year=2004
|title=Moreton waves observed at Hida Observatory
|journal = Proceedings IAU Symposium
|issue = 223
|pages = 367–370
|doi=10.1017/S1743921304006143
|url=http://journals.cambridge.org/production/action/cjoGetFulltext?fulltextid=288483
|accessdate = 2006-12-11
|volume = 2004 }}</ref>
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==Coronal clouds==

"Coronal clouds, type IIIg, form in space above a spot area and rain streamers upon it."<ref name=Pettit43>{{ cite journal
|author=Edison Pettit
|title=The Properties of Solar Prominences as Related to Type
|journal=Astrophysical Journal
|month=July
|year=1943
|volume=98
|issue=7
|pages=6-19
|url=
|bibcode=1943ApJ....98....6P
|doi=10.1086/144539
|pmid=
|accessdate=2011-08-01 }}</ref>

"[C]oronal magnetic bottles, produced by flares, [may] serve as temporary traps for solar cosmic rays ... It is the expansion of these bottles at velocities of 300–500 km/s which allows fast azimuthal propagation of solar cosmic rays independent of energy. A coronagraph on [[w:OSO 7|Os 7]] observed a coronal cloud which was associated with bifurcation of the underlying coronal structure."<ref name="Schatten">{{cite journal
|author=K. H. Schatten, D. J. Mullan
|title=Fast azimuthal transport of solar cosmic rays via a coronal magnetic bottle
|journal=Journal of Geophysical Research
|month=December 1,
|year=1977
|volume=82
|issue=35
|pages=5609-20
|url=http://www.agu.org/pubs/crossref/1977/JA082i035p05609.shtml
|arxiv=
|bibcode=
|doi=10.1029/JA082i035p05609
|pmid=
|accessdate=2013-07-07 }}</ref>

In a coronal cloud are magnetohydrodynamic plasma flux tubes along magnetic field lines.<ref name=Aschwanden>{{ cite journal
  | author = M. J. Aschwanden
  | title = An evaluation of coronal heating models for Active Regions based on Yohkoh, SOHO, and TRACE observations
  | journal = The Astrophysical Journal
  | volume = 560
  | issue = 2
  | pages = 1035–44
  | year = 2001
  | doi = 10.1086/323064
| bibcode=2001ApJ...560.1035A }}</ref>

==Coronal heating==

"The photosphere of the Sun has an effective temperature of 5,570 K<ref name=Massey>{{ cite journal
|author=Massey P
|author2=Silva DR
|author3=Levesque EM
|author4=Plez B
|author5=Olsen KAG
|author6=Clayton GC
|author7=Meynet G
|author8=Maeder A
|title=Red Supergiants in the Andromeda Galaxy (M31)
|journal=The Astrophysical Journal
|volume=703
|year=2009
|issue=1
|page=420
|doi=10.1088/0004-637X/703/1/420
|bibcode=2009ApJ...703..420M }}</ref> yet its corona has an average temperature of 1–2 x 10<sup>6</sup> K.<ref name=Erdelyi>{{ cite journal
|author=Erdèlyi R
|author2=Ballai I
|title=Heating of the solar and stellar coronae: a review
|year=2007
|journal=Astron Nachr
|volume=328
|issue=8
|page=726
|doi=10.1002/asna.200710803
|bibcode=2007AN....328..726E }}</ref> However, the hottest regions are 8–20 x 10<sup>6</sup> K.<ref name=Erdelyi/> The high temperature of the corona shows that it is heated by something other than direct heat conduction from the photosphere.<ref name=Russell2001>{{ cite book
|author=Russell CT
|title=Space Weather (Geophysical Monograph)
|year=2001
|publisher=American Geophysical Union
|chapter=Solar wind and interplanetary magnetic field: A tutorial
|editor=Song, Paul
|editor2=Singer, Howard J.
|editor3=Siscoe, George L.
|isbn=9780875909844
|pages=73–88
|url=http://www-ssc.igpp.ucla.edu/personnel/russell/papers/SolWindTutorial.pdf }}</ref>

It is thought that the energy necessary to heat the corona is provided by turbulent motion in the convection zone below the photosphere, and two main mechanisms have been proposed to explain coronal heating.<ref name=Erdelyi/> The first is [[w:wave|wave]] heating, in which sound, gravitational or magnetohydrodynamic waves are produced by turbulence in the convection zone.<ref name=Erdelyi/> These waves travel upward and dissipate in the corona, depositing their energy in the ambient gas in the form of heat.<ref name=Alfven>{{ cite journal
|author=Alfvén H
|title=Magneto-hydrodynamic waves, and the heating of the solar corona
|bibcode=1947MNRAS.107..211A
|journal=Monthly Notices of the Royal Astronomical Society
|volume=107
|page=211
|year=1947 }}</ref> The other is [[w:magnetic field|magnetic]] heating, in which magnetic energy is continuously built up by photospheric motion and released through [[w:magnetic reconnection|magnetic reconnection]] in the form of large [[w:solar flare|solar flare]]s and myriad similar but smaller events—[[w:nanoflares|nanoflares]].<ref name=Parker2>{{ cite journal
|author=Parker EN
|title=Nanoflares and the solar X-ray corona
|journal=The Astrophysical Journal
|volume=330
|page=474
|year=1988
|doi=10.1086/166485
|bibcode=1988ApJ...330..474P }}</ref>

Currently, it is unclear whether waves are an efficient heating mechanism. All waves except [[w:Alfvén wave|Alfvén wave]]s have been found to dissipate or refract before reaching the corona.<ref name=Sturrock>{{ cite journal
|author=Sturrock PA, Uchida Y
|title=Coronal heating by stochastic magnetic pumping
|journal=The Astrophysical Journal
|volume=246
|page=331
|year=1981
|doi=10.1086/158926
|bibcode=1981ApJ...246..331S }}</ref> In addition, Alfvén waves do not easily dissipate in the corona. Current research focus has therefore shifted towards flare heating mechanisms.<ref name=Erdelyi/>

==Solar winds==
[[Image:1024px--D3- LighningStormPanorama.jpg|thumb|right|300px|A lightning storm over England is imaged. Credit: Catalin Fatu.{{tlx|fairuse}}]]
"The sun spits out charged particles that hit our atmosphere two to four days later at 1.5-2.7 million kph, but it does not do so evenly."<ref name=Luntz>{{ cite web
|author=Stephen Luntz
|title=Solar Activity Could Cause Lightning Storms On Earth
|location=
|date=May 16, 2014
|url=http://www.iflscience.com/space/solar-activity-could-cause-lightning-storms-earth
|accessdate=2014-08-31 }}</ref>

"The solar wind is not continuous, it has slow and fast streams. Because the Sun rotates, these streams can be sent out behind each other - so if you have a fast solar wind catching up with a slow solar wind, it causes a concentration to occur."<ref name=Scott>{{ cite web
|author=Christ Scott
|title=Solar Activity Could Cause Lightning Storms On Earth
|location=
|date=May 16, 2014
|url=http://www.iflscience.com/space/solar-activity-could-cause-lightning-storms-earth
|accessdate=2014-08-31 }}</ref>

"The slow phase is composed similarly to the solar corona while fast particles have a composition close to that of the photosphere, the outer layer of the sun that produces the light."<ref name=Luntz/>

There is "a 31% increase in average lightning strikes over central England (422 to 321) in the 40 days after major solar wind events compared to the days beforehand. Lightning peaked 12-18 days after the wind's arrival. A matching increase in thundery days provided supporting evidence."<ref name=Luntz/>

"It's unexpected, because these streams of particles bring with them an enhanced magnetic field - and this shields Earth from the very high-energy cosmic rays from outside of the Solar System.”<ref name=Scott/>

"The reduction in cosmic rays is only around 1%, but still noticeable. Cosmic rays emitted by supernovae are thought to trigger lighting strikes, and it was expected that the shielding effect of the solar wind would cause a reduction in lightning, rather than an increase."<ref name=Luntz/>

Sunspot "numbers negatively correlate with thunder days in other parts of the world."<ref name=Luntz/>

"High speed streams were found to occur after periods when the sun was putting out less light, but sunspot numbers increased. Scott and his fellow authors attribute this to the streams coming from an active region appearing on the eastern side of the sun."<ref name=Luntz/>

"We propose that these particles, while not having sufficient energies to reach the ground and be detected there, nevertheless electrify the atmosphere as they collide with it, altering the electrical properties of the air and thus influencing the rate or intensity at which lightning occurs."<ref name=Scott/>
{{clear}}

==Earth==
{{main|Rocks/Rocky objects/Earth}}
"Traces of magnetism in ancient rocks suggest that Earth had a magnetic field as far back as 4.2 billion years ago. That earlier field was likely generated by heat within the planet driving circulation within the molten core. But over time, computer simulations suggest, the heat-driven circulation wouldn’t have been strong enough alone to continue to power a strong magnetic field. Instead, the field began to shut down, signaled in the rock record by weakening intensities and rapid polarity reversals over millions of years. And then, at some point, Earth’s inner core began to crystallize, jump-starting the geodynamo and generating a new, strong magnetic field."<ref name=Gramling/>

"Data from [seismic] waves, rotations and inertia of the whole Earth, magnetic-field dynamo theory, and laboratory experiments on melting and alloying of iron all contribute to the identification of the composition of the inner and outer core. The core is presumed to be composed principally of iron, with about 10 percent alloy of oxygen or sulfur or nickel, or perhaps some combination of these three elements."<ref name=Robertson>{{ cite web
|author=Eugene C. Robertson
|title=The Interior of the Earth
|publisher=USGS
|location=Reston, Virginia USA
|date=14 January 2011
|url=http://pubs.usgs.gov/gip/interior/
|accessdate=2014-12-01 }}</ref>

"Radioactive potassium, uranium and thorium are thought to be the three main sources of heat in the Earth's interior, aside from that generated by the formation of the planet. Together, the heat keeps the mantle actively churning and the core generating a protective magnetic field."<ref name=Sanders>{{ cite book
|author=Robert Sanders
|title=Radioactive potassium may be major heat source in Earth's core
|publisher=University of California Berkeley
|location=Berkeley, Californis USA
|date=December 10, 2003
|url=http://www.berkeley.edu/news/media/releases/2003/12/10_heat.shtml
|accessdate=2014-03-28 }}</ref>

"Modelers need heat, so this is one source, because the radiogenic isotope of potassium can produce heat and that can help power convection in the core and drive the magnetic field. They proved it could go in. What's important is how much is pulled out of the silicate. There's still work to be done."<ref name=Buffett>{{ cite book
|author=Bruce Buffett
|title=Radioactive potassium may be major heat source in Earth's core
|publisher=University of California Berkeley
|location=Berkeley, Californis USA
|date=December 10, 2003
|url=http://www.berkeley.edu/news/media/releases/2003/12/10_heat.shtml
|accessdate=2014-03-28 }}</ref>

"The heat generated in the core turns the iron into a convecting dynamo that maintains a magnetic field strong enough to shield the planet from the solar wind. This heat leaks out into the mantle, causing convection in the rock that moves crustal plates and fuels volcanoes."<ref name=Sanders/>

In the case of the Earth, the magnetic field is induced and constantly maintained by the convection of liquid iron in the outer core. A requirement for the induction of field is a rotating fluid. Rotation in the outer core is supplied by the Coriolis effect caused by the rotation of the Earth. The Coriolis force tends to organize fluid motions and electric currents into columns aligned with the rotation axis. Induction or creation of magnetic field is described by the induction equation:

:<math>\frac{\partial \mathbf{B}}{\partial t} = \eta \nabla^2 \mathbf{B} + \nabla \times (\mathbf{u} \times \mathbf{B}),</math>

where '''u''' is a velocity, '''B''' is the magnetic field, ''t'' is time, and <math>\eta=1/\sigma\mu</math> is the magnetic diffusivity with <math>\sigma</math> electrical conductivity and <math>\mu</math> permeability. The ratio of the second term on the right hand side to the first term gives the Magnetic Reynolds number, a dimensionless ratio of advection of a magnetic field to diffusion.

"Of course, you need a force to move fluid towards the tangent cylinder. This could be provided by buoyancy, or perhaps more likely from changes in the magnetic field within the core."<ref name=Hollerbach>{{ cite web
|author=Rainer Hollerbach
|title=Iron 'jet stream' detected in Earth's outer core
|publisher=BBC
|location=London, England
|date=19 December 2016
|url=http://www.bbc.com/news/science-environment-38372342
|accessdate=2017-01-11 }}</ref>

"As the inner core cools, crystallizing iron releases impurities, sending lighter molten material into the liquid outer core. This upwelling, combined with the Earth's rotation, drives convection, forcing the molten metal into whirling vortices. These vortices stretch and twist magnetic field lines, creating Earth’s magnetic field. Currently, the center of the field, called an axis, emerges in the Arctic Ocean west of Ellesmere Island, about 300 miles (500 kilometers) from the geographic North Pole."<ref name=Oskin>{{ cite web
|author=Becky Oskin
|title=Why Earth's Magnetic Field Is Wonky
|publisher=LiveScience
|location=
|date=July 18, 2012
|url=http://www.livescience.com/21668-why-earth-magnetic-field-wonky.html
|accessdate=2013-05-14 }}</ref>

"The lopsided growth of the inner core makes convection in the outer core a little bit lopsided, and that then induces the geomagnetic field to have this lopsided or eccentric character too".<ref name=Olson2012>{{ cite web
|author=Peter Olson
|title=Why Earth's Magnetic Field Is Wonky
|publisher=LiveScience
|location=
|date=July 18, 2012
|url=http://www.livescience.com/21668-why-earth-magnetic-field-wonky.html
|accessdate=2013-05-14 }}</ref>

"Magnetic particles trapped and aligned in rocks reveal that the magnetic north pole wandered around the Western Hemisphere over the past 10,000 years, and circled the Eastern Hemisphere before that — a result mirrored by the numerical test."<ref name=Oskin/>

"Earth’s magnetic field [...] is powered by circulation of iron-rich fluid in the core. [...] Earth’s solid inner core [may have] formed after 565 million years ago, saving a weakening magnetic field from collapse."<ref name=Gramling>{{ cite journal
|author=Carolyn Gramling
|title=Earth’s core may have hardened just in time to save its magnetic field
|journal=Science News
|date=March 2, 2019
|volume=195
|issue=4
|pages=13
|url=https://www.sciencenews.org/article/earth-core-solidified-just-time-save-magnetic-field
|arxiv=
|bibcode=
|doi=
|pmid=
|accessdate=13 March 2019 }}</ref>

"We don’t have many real benchmarks for the thermal history of our planet."<ref name=Olson>{{ cite journal
|author=Peter Olson
|title=Earth’s core may have hardened just in time to save its magnetic field
|journal=Science News
|date=March 2, 2019
|volume=195
|issue=4
|pages=13
|url=https://www.sciencenews.org/article/earth-core-solidified-just-time-save-magnetic-field
|arxiv=
|bibcode=
|doi=
|pmid=
|accessdate=13 March 2019 }}</ref>

"Proposed ages have been anywhere from 500 million years ago to older than 2.5 billion years."<ref name=Tarduno>{{ cite journal
|author=John Tarduno
|title=Earth’s core may have hardened just in time to save its magnetic field
|journal=Science News
|date=March 2, 2019
|volume=195
|issue=4
|pages=13
|url=https://www.sciencenews.org/article/earth-core-solidified-just-time-save-magnetic-field
|arxiv=
|bibcode=
|doi=
|pmid=
|accessdate=13 March 2019 }}</ref>

"The interplay of the two layers drives the geodynamo, the circulation of iron-rich fluid that powers the magnetic field. That field, surrounding the planet, protects Earth from being battered by the solar wind, a constant flow of charged particles ejected by the sun. As the inner core cools and crystallizes, the composition of the remaining fluid changes; more buoyant liquid rises like a plume while the cooling crystals sink. That self-sustaining, density-driven circulation generates a strong magnetic field with two opposing poles, north and south, or polarity."<ref name=Gramling/>

"Traces of magnetism in ancient rocks suggest that Earth had a magnetic field as far back as 4.2 billion years ago. That earlier field was likely generated by heat within the planet driving circulation within the molten core. But over time, computer simulations suggest, the heat-driven circulation wouldn’t have been strong enough alone to continue to power a strong magnetic field. Instead, the field began to shut down, signaled in the rock record by weakening intensities and rapid polarity reversals over millions of years. And then, at some point, Earth’s inner core began to crystallize, jump-starting the geodynamo and generating a new, strong magnetic field."<ref name=Gramling/>

Magnetic "inclusions within a suite of rocks in Quebec, Canada, dating to about 565 million years ago [...] — needlelike iron-rich grains that align themselves with the orientation of the magnetic field that existed when the rocks formed — show that the planet’s magnetic field was extremely weak at that time. These paleo-intensity values were 10 times less than the present magnetic field, lower than anything observed previously. It suggested there’s something fundamental going on in the core."<ref name=Tarduno/>

"Combined with previous studies that have found that the magnetic field was also rapidly reversing polarity during that time period, the new result indicates that Earth’s field may have been on the point of collapse about 565 million years ago. That suggests that the inner core hadn’t yet solidified."<ref name=Gramling/>

"Because the rocks bearing the magnetic grains didn’t cool instantaneously but over a long time, the data represent an average field intensity for about a 100,000-year period. [A] true, persistent signal [was found]. Computer simulations have suggested that the weak field phase may have lasted much longer, from about 900 million to 600 million years ago."<ref name=Olson/>

If "the core is cooling quickly, that means it was very hot in the recent past, and that the lower mantle was very hot in the recent past — so hot that both were molten just 1 billion to 2 billion years ago. We absolutely do not see that in the rock record."<ref name=Driscoll>{{ cite journal
|author=Peter Driscoll
|title=Earth’s core may have hardened just in time to save its magnetic field
|journal=Science News
|date=March 2, 2019
|volume=195
|issue=4
|pages=13
|url=https://www.sciencenews.org/article/earth-core-solidified-just-time-save-magnetic-field
|arxiv=
|bibcode=
|doi=
|pmid=
|accessdate=13 March 2019 }}</ref>

Palaeointensity "data from the Ediacaran (~565 million years old) Sept-Îles intrusive suite measured on single plagioclase and clinopyroxene crystals that hosted single-domain magnetic inclusions [indicates] a time-averaged dipole moment of ~0.7 × 10<sup>22</sup> A m<sup>2</sup>, the lowest value yet reported for the geodynamo from extant rocks and more than ten times smaller than the strength of the present-day field."<ref name=Bono>{{ cite journal
|author=Richard K. Bono, John A. Tarduno, Francis Nimmo & Rory D. Cottrell
|title=Young inner core inferred from Ediacaran ultra-low geomagnetic field intensity
|journal=Nature Geoscience
|date=28 January 2019
|volume=12
|issue=
|pages=143–147
|url=https://www.nature.com/articles/s41561-018-0288-0
|arxiv=
|bibcode=
|doi=
|pmid=
|accessdate=13 March 2019 }}</ref>

"Palaeomagnetic directional studies of these crystals define two polarities with an unusually high angular dispersion (S = ~26°) at a low latitude. Together with 14 other directional data sets that suggest a hyper-reversal frequency, these extraordinary low field strengths suggest an anomalous field behaviour, consistent with predictions of geodynamo simulations, high thermal conductivities and an Ediacaran onset age of inner core growth."<ref name=Bono/>
{{clear}}

==Magnetic field reversals==
{{main|Magnetic field reversals/Earth}}
[[Image:East_Pacific_Rise_seafloor_magnetic_profile_-_observed_vs_calculated.png|thumb|250px|right|The graph shows a comparison of the observed magnetic profile for the seafloor across the East Pacific Rise against a profile calculated from the Earth's known magnetic reversals, assuming a constant rate of spreading. Credit: W. Jacquelyne Kious and Robert I. Tilling, USGS.{{tlx|free media}}]]
The graph in the center shows a comparison of the observed magnetic profile for the seafloor across the East Pacific Rise against a profile calculated from the Earth's known magnetic reversals, assuming a constant rate of spreading.
{{clear}}

==Theoretical magnetic field reversals==
[[Image:Oceanic.Stripe.Magnetic.Anomalies.Scheme.svg|thumb|right|250px|The image shows a theoretical model of the formation of magnetic striping. Credit: US Geological Survey.{{tlx|free media}}]]
On the right is an image of a model for the formation of magnetic striping on Earth.

Here's a [[Definitions/Theory#Theoretical definition|theoretical definition]]:

'''Def.''' a polarity reversal of the global magnetic field of an astronomical object or body is called a '''magnetic field reversal'''.
{{clear}}

==Remanent magnetization==
[[Image:LIRM anomaly with archaeological hearths.jpg|thumb|upright|right|250px|Lightning-induced remanent magnetization (LIRM) is mapped during a magnetic field gradient survey of an archaeological site located in Wyoming, United States. Credit: [[w:user:Pöhönen|Pöhönen]].{{tlx|fairuse}}]]
The movement of electrical charges produces a magnetic field, where the intense currents of a lightning discharge create a fleeting but very strong magnetic field and the lightning current path passes through rock, soil, or metal these materials can become permanently magnetized, known as lightning-induced remanent magnetism, or LIRM which follow the least resistive path, often horizontally near the surface<ref>{{cite journal
|title=The Re-magnetization of a Surface Outcrop by Lightning Currents
|doi=10.1111/j.1365-246X.1961.tb02963.x
|date=1961
|last1=Graham
|first1=K.W.T.
|journal=Geophysical Journal International
|volume=6
|issue=1
|page=85
|bibcode = 1961GeoJ....6...85G }}</ref><ref>Cox A. (1961). Anomalous Remanent Magnetization of Basalt [url=https://web.archive.org/web/20130529011301/http://pubs.usgs.gov/bul/1083e/report.pdf] May 29, 2013 . U.S. Geological Survey Bulletin 1038-E, pp. 131–160.</ref> but sometimes vertically, where faults, ore bodies, or ground water offers a less resistive path.<ref>Bevan B. (1995). "Magnetic Surveys and Lightning". ''Near Surface Views'' (newsletter of the Near Surface Geophysics section of the Society of Exploration Geophysics). October 1995, pp. 7–8.</ref> One theory suggests that lodestones, natural magnets encountered in ancient times, were created in this manner.<ref>{{cite journal
| doi=10.1029/1999GL900496
| first=Peter
| last=Wasilewski
|author2=Günther Kletetschka
 | title=Lodestone: Nature's only permanent magnet – What it is and how it gets charged
|url=https://web.archive.org/web/20061003193325/http://lep694.gsfc.nasa.gov/gunther/gunther/Wasilewski1999.pdf
| archivedate=October 3, 2006
| journal=Geophysical Research Letters
| volume=26
| issue=15
| pages=2275–78
| date=1999
| accessdate=July 13, 2009|bibcode = 1999GeoRL..26.2275W }}</ref>

Lightning-induced magnetic anomalies can be mapped in the ground,<ref>{{Cite journal
|last=Sakai
|first=H. S.
|last2=Sunada
|first2=S.
|last3=Sakurano
|first3=H.
|date=1998
|title=Study of Lightning Current by Remanent Magnetization
|journal=Electrical Engineering in Japan
|volume=123
|issue=4
|pages=41–47
|doi=10.1002/(SICI)1520-6416(199806)123:4<41::AID-EEJ6>3.0.CO;2-O }}</ref><ref> Archaeo-Physics, LLC Lightning-induced magnetic anomalies on archaeological sites [https://web.archive.org/web/20071012080847/http://www.archaeophysics.com/pubs/LIRM.html] October 12, 2007. Archaeophysics.com. Retrieved on June 23, 2012.</ref> and analysis of magnetized materials can confirm lightning was the source of the magnetization<ref>{{Cite journal
|last=Maki
|first=David
|date=2005
|title=Lightning strikes and prehistoric ovens: Determining the source of magnetic anomalies using techniques of environmental magnetism
|journal=Geoarchaeology
|volume=20
|issue=5
|pages=449–459
|doi=10.1002/gea.20059
|url=https://web.archive.org/web/20130515025335/http://www.archaeophysics.com/pubs/lightning-oven.pdf
|archivedate=May 15, 2013
|citeseerx=10.1.1.536.5980 }}</ref> and provide an estimate of the peak current of the lightning discharge.<ref>{{Cite journal
|last=Verrier
|first=V.
|last2=Rochette
|first2=P.
|date=2002
|title=Estimating Peak Currents at Ground Lightning Impacts Using Remanent Magnetization
|journal=Geophysical Research Letters
|volume=29
|issue=18
|page=1867
|doi=10.1029/2002GL015207
|bibcode = 2002GeoRL..29.1867V }}</ref>

Magnetic fields generated by plasma may induce hallucinations in subjects located within 200 meters of a severe lightning storm.<ref>{{cite web
|url=https://www.technologyreview.com/s/418887/magnetically-induced-hallucinations-explain-ball-lightning-say-physicists/
|title = Magnetically Induced Hallucinations Explain Ball Lightning, Say Physicists }}</ref>
{{clear}}

==Auroras==
{{main|Plasmas/Plasma objects/Auroras}}
[[Image:Aurora Iceland 2015 Carlos Gauna 625.jpg|thumb|right|300px|This dramatic panorama shows a colourful, shimmering auroral curtain reflected in a placid Icelandic lake. Credit: Carlos Gauna. {{tlx|fairuse}}]]
'''Auroras''' can be caused by electrons being absorbed into an atmosphere.

The "dramatic panorama [on the right shows a colorful], shimmering auroral curtain reflected in a placid Icelandic lake. The image was taken on 18 March 2015 by Carlos Gauna, near Jökulsárlón Glacier Lagoon in southern Iceland."<ref name=ESAGauna>{{ cite book
|author=European Space Agency
|title=Aurora over Icelandic Lake
|publisher=ESA
|location=
|date=9 April 2015
|url=http://sci.esa.int/cluster/55767-aurora-over-icelandic-lake/
|accessdate=2015-04-12 }}</ref>

"The celestial display was generated by a coronal mass ejection, or CME, on 15 March. Sweeping across the inner Solar System at some 3 million km per hour, the eruption reached Earth, 150 million kilometres away, in only two days. The gaseous cloud collided with Earth’s magnetic field at around 04:30 GMT on 17 March."<ref name=ESAGauna/>

"When the charged particles from the Sun penetrate Earth's magnetic shield, they are channelled downwards along the magnetic field lines until they strike atoms of gas high in the atmosphere. Like a giant fluorescent neon lamp, the interaction with excited oxygen atoms generates a green or, more rarely, red glow in the night sky, while excited nitrogen atoms yield blue and purple colours."<ref name=ESAGauna/>

"Auroral displays are not just decorative distractions. They are most frequent when the Sun's activity nears its peak roughly every 11 years. At such times, the inflow of high-energy particles and the buffeting of Earth’s magnetic field may sometimes cause power blackouts, disruption of radio communications, damage to satellites and even threaten astronaut safety."<ref name=ESAGauna/>
{{clear}}

==Jupiter==
{{main|Jupiter}}
[[Image:Jupiter xray ill.jpg|thumb|right|250px|Jupiter shows intense X-ray emission associated with auroras in its polar regions (Chandra observatory X-ray image on the left). The accompanying schematic illustrates how Jupiter's unusually frequent and spectacular auroral activity is produced. Observation period: 17 hrs, February 24-26, 2003. Credit: X-ray: NASA/CXC/MSFC/R.Elsner et al.; Illustration: CXC/M.Weiss.]]
In the image at right is a diagram describing interaction with the local magnetic field. Jupiter's strong, rapidly rotating magnetic field (light blue lines in the figure) generates strong electric fields in the space around the planet. Charged particles (white dots), "trapped in Jupiter's magnetic field, are continually being accelerated (gold particles) down into the atmosphere above the polar regions, so auroras are almost always active on Jupiter. Electric voltages of about 10 million volts, and currents of 10 million amps - a hundred times greater than the most powerful lightning bolts - are required to explain the auroras at Jupiter's poles, which are a thousand times more powerful than those on Earth. On Earth, auroras are triggered by solar storms of energetic particles, which disturb Earth's magnetic field. As shown by the swept-back appearance in the illustration, gusts of particles from the Sun also distort Jupiter's magnetic field, and on occasion produce auroras."<ref name=Elsner>{{ cite book
|author=X-ray: NASA/CXC/MSFC/R.Elsner
|author2=Illustration: CXC/M.Weiss
|title=Jupiter: Chandra Probes High-Voltage Auroras on Jupiter
|publisher=Harvard-Smithsonian Center for Astrophysics
|location=Cambridge, Massachusetts
|date=March 2, 2005
|url=http://chandra.harvard.edu/photo/2005/jupiter/
|accessdate=2012-07-11 }}</ref>

Supporting the idea of water clouds are the flashes of lightning detected in the atmosphere of Jupiter that can be up to a thousand times as powerful as lightning on Earth.<ref>{{cite web
|editor=Watanabe, Susan
|date=February 25, 2006
|url=http://www.nasa.gov/vision/universe/solarsystem/galileo_end.html
|title=Surprising Jupiter: Busy Galileo spacecraft showed jovian system is full of surprises
|publisher=NASA
|accessdate=February 20, 2007 }}</ref> The water clouds are assumed to generate thunderstorms in the same way as terrestrial thunderstorms, driven by the heat rising from the interior.<ref>{{cite journal
|last=Kerr
|first=Richard A.
|title=Deep, Moist Heat Drives Jovian Weather
|journal=Science
|date=2000
|volume=287
|issue=5455
|pages=946–947
|url=http://www.sciencemag.org/cgi/content/full/287/5455/946b
|doi=10.1126/science.287.5455.946b
|accessdate=February 24, 2007 }}</ref>

As the spacecraft passed behind the planet, it observed flashes of lightning in the night side atmosphere.<ref name="burgess">{{cite book
|first=Eric
|last=Burgess
|date=1982
|title=By Jupiter: Odysseys to a Giant
|publisher=Columbia University Press
|location=New York
|isbn=978-0-231-05176-7 }}</ref><ref name="voyager1">{{cite web
|date=January 14, 2003
|url=http://voyager.jpl.nasa.gov/science/jupiter.html
|title=Jupiter
|publisher=NASA/JPL
|accessdate=November 28, 2006 }}</ref>
{{clear}}

==Saturn==

Starting in early 2005, scientists used ''Cassini'' to track lightning on Saturn. The power of the lightning is approximately 1,000&nbsp;times that of lightning on Earth.<ref>{{cite web
|title=Astronomers Find Giant Lightning Storm At Saturn
|date=2007
|accessdate=27 July 2007
|publisher=ScienceDaily LLC
|url=https://www.webcitation.org/616W9ngSD?url=http://www.sciencedaily.com/releases/2006/02/060215090726.htm
|archivedate=21 August 2011 }}</ref>

The Radio and Plasma Wave Science instrument (RPWS) on ''Cassini-Huygens'' studied the configuration of Saturn's magnetic field and its relationship to Saturn Kilometric Radiation (SKR), as well as monitoring and mapping Saturn's ionosphere, plasma, and lightning from Saturn's (and possibly Titan's) atmosphere.<ref name="instruments-cassini">{{cite web
|url=http://saturn.jpl.nasa.gov/spacecraft/cassiniorbiterinstruments/
|title=Cassini Orbiter Instruments
|publisher=Saturn.jpl.nasa.gov
|accessdate=August 20, 2011 }}</ref><ref>{{cite web
|url=http://caps.space.swri.edu/
|title=CAPS team page
|publisher=Caps.space.swri.edu
|accessdate=August 20, 2011 }}</ref>

==Local Interstellar Mediums==
{{main|Interstellar medium}}
In 2009, ''Voyager 2'' data suggested that the magnetic strength of the local interstellar medium was much stronger than expected (370 to 550 picotesla (pT), against previous estimates of 180 to 250 pT). The fact that the Local Interstellar Cloud is strongly magnetized could explain its continued existence despite the pressures exerted upon it by the winds that blew out the Local Bubble.<ref>{{cite journal
|url=http://www-personal.umich.edu/~tamas/TIGpapers/2009/2009_Opher_nature.pdf
|title=A strong, highly-tilted interstellar magnetic field near the Solar System
|journal=Nature
|first1=M.
|last1=Opher
|first2=F.
|last2=Alouani Bibi
|first3=G.
|last3=Toth
|first4=J. D.
|last4=Richardson
|first5=V. V.
|last5=Izmodenov
|first6=T. I.
|last6=Gombosi
|volume=462
|date=December 24–31, 2009
|doi=10.1038/nature08567
|bibcode=2009Natur.462.1036O
|pages=1036–1038
|pmid=20033043 }}</ref>

==White dwarfs==
{{main|Stars/Dwarfs/Whites}}
"White dwarfs are end-products of stellar evolution. The fundamental properties of the dominant group of nonmagnetic white dwarfs have been invaluable in constraining the theory of single star evolution."<ref name=Berdyugina>{{ cite journal
|author=S. V. Berdyugina, A. V. Berdyugin, and V. Piirola
|title=Molecular Magnetic Dichroism in Spectra of White Dwarfs
|journal=Physical Review Letters
|month=August
|year=2007
|volume=99
|issue=9
|pages=091101-1 to -5
|url=http://www3.kis.uni-freiburg.de/~sveta/papers/berdyugina_PRL.pdf
|bibcode= 2007PhRvL..99i1101B
|doi=10.1103/PhysRevLett.99.091101
|pmid=
|accessdate=2011-08-10 }}</ref> Of the 2551 white dwarf stars from the full spectroscopic white dwarf and hot subdwarf sample within the Sloan Digital Sky Survey (SDSS) first data release, DR1, 1888 are non-magnetic DA types and 171, non-magnetic DBs.<ref name=Kleinman>{{ cite journal
|author=S. J. Kleinman, Hugh C. Harris, Daniel J. Eisenstein, James Liebert, Atsuko Nitta, 
Jurek Krzesi ́nski, Jeffrey A. Munn, Conard C. Dahn, Suzanne L. Hawley, Jeffrey R. Pier, Gary Schmidt, Nicole M. Silvestri, J. Allyn Smith, Paula Szkody, Michael A. Strauss, G. R. Knapp, Matthew J. Collinge, A. S. Mukadam, D. Koester, Alan Uomoto, D. J. Schlegel, Scott F. Anderson, J. Brinkmann, D.Q. Lamb, Donald P. Schneider, and Donald G. York
|title=A Catalog of Spectroscopically Identified White Dwarf Stars in the First Data Release of the Sloan Digital Sky Survey
|journal=The Astrophysical Journal
|month=May
|year=2004
|volume=607
|issue=1
|pages=426-44
|url=http://iopscience.iop.org/0004-637X/607/1/426/fulltext
|bibcode= 2004ApJ...607..426K
|doi=10.1086/383464
|pmid=
|accessdate=2011-08-10 |arxiv = astro-ph/0402209 }}</ref> "White dwarfs are the most readily studied of the end products of stellar evolution. Investigations of white dwarfs have generally focused on the dominant group of the nonmagnetic variety for which realistic model atmospheres can be constructed and stellar parameters deduced."<ref name=Wickramasinghe>{{ cite journal
|author=D. T. Wickramasinghe and Lilia Ferrario
|title=Magnetism in Isolated and Binary White Dwarfs
|journal=Publications of the Astronomical Society of the Pacific
|month=July
|year=2000
|volume=112
|issue=
|pages=873-924
|url=http://www.astro.caltech.edu/~srk/ay125/magnetismwd.pdf
|bibcode= 2000PASP..112..873W
|doi= 10.1086/316593
|pmid=
|accessdate=2011-08-10 }}</ref> "White dwarfs are intensively studied end products of stellar evolution. However, investigations of white dwarfs have generally focused on the dominant group of nonmagnetic stars for which realistic model atmospheres can be constructed and fundamental properties, such as their masses or interior chemical composition can be determined."<ref name=Sliwinski>{{ cite journal
|author=Śliwiński M.S., Krzyczkowska L.I.
|title=The movie about the magnetism in isolated white dwarfs, In: ''Magnetic stars'', Proceedings of the International Conference, held in the Special Astrophysical Observatory of the Russian AS, August 27-31, 2003
|month=October
|year=2004
|editor=Yu. Glagolevskij, D. Kudryavtsev, I. Romanyuk, Nizhnij Arkhyz
|issue=
|pages=268-71
|url=http://unipaq.sao.ru/hq/lizm/conferences/pdf/2003/2003_p268.pdf
|bibcode=2004mast.conf..268S
|doi=
|pmid=
|accessdate=2011-08-10 }}</ref>

==Satellites==
[[Image:Swarm-satellite.jpg|thumb|right|300px|The "Swarm" satellites have been flying around Earth since Fall of 2013. Credit: Christoph Seidler, ESA/DTU.]]
[[Image:Depiction of where the jet is moving - in the outer core.png|left|thumb|250px|Depiction shows where the molten iron jet is moving - in the outer core. Credit: ESA.]]
"Three [Swarm] satellites of the European Space Agency (ESA) have measured the magnetic field of Earth more precisely than ever before."<ref name=Seidler>{{ cite book
|author=Christoph Seidler
|author2=translated by Anne-Marie de Grazia
|title=Earth's weakening magnetic field
|publisher=Q-Mag.org
|location=
|date=19 June 2014
|url=http://www.q-mag.org/earths-weakening-magnetic-field.html
|accessdate=2014-10-21 }}</ref>
{{clear}}

==See also==
{{div col|colwidth=20em}}
* [[Gamma-ray astronomy]]
* [[Radiation/Neutrons|Neutron astronomy]]
* [[Optical astronomy]]
* [[Submillimeter astronomy]]
* [[X-ray astronomy]]
{{Div col end}}

==References==
{{reflist|2}}

==External links==
* [http://www.iau.org/ International Astronomical Union]
* [http://nedwww.ipac.caltech.edu/ NASA/IPAC Extragalactic Database - NED]
* [http://nssdc.gsfc.nasa.gov/ NASA's National Space Science Data Center]
* [http://www.osti.gov/ Office of Scientific & Technical Information]
* [http://www.adsabs.harvard.edu/ The SAO/NASA Astrophysics Data System]
* [http://www.scirus.com/srsapp/advanced/index.jsp?q1= Scirus for scientific information only advanced search]
* [http://cas.sdss.org/astrodr6/en/tools/quicklook/quickobj.asp SDSS Quick Look tool: SkyServer]
* [http://simbad.u-strasbg.fr/simbad/ SIMBAD Astronomical Database]
* [http://nssdc.gsfc.nasa.gov/nmc/SpacecraftQuery.jsp Spacecraft Query at NASA]
* [http://heasarc.gsfc.nasa.gov/cgi-bin/Tools/convcoord/convcoord.pl Universal coordinate converter]

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