Editing Geyser (section)

== Extraterrestrial geyser-like features ==
{{See also|Cryovolcano|Geysers on Mars}}There are many bodies in the [[Solar System]] where eruptions which superficially resemble terrestrial geysers have been observed or are believed to occur. Despite being commonly referred to as geysers, they are driven by fundamentally different processes, consist of a wide range of [[Volatile (astrogeology)|volatiles]], and can occur on vastly disparate scales; from the modestly sized [[Geysers on Mars|Martian carbon dioxide jets]] to the immense [[Enceladus#South polar plumes|plumes of Enceladus]]. Generally, there are two broad categories of feature commonly referred to as geysers: [[Sublimation (phase transition)|sublimation]] plumes, and [[Cryovolcano|cryovolcanic]] plumes (also referred to as cryogeysers).<ref>{{cite book |last1=Fagents |first1=SA |last2=Lopes |first2=RM |last3=Quick |first3=LC |last4=Gregg |first4=TK |year=2022 |chapter=Cryovolcanism |title=Planetary volcanism across the solar system |pages=161–234 |publisher=Elsevier |bibcode=2022pvss.book.....G |url=https://ntrs.nasa.gov/api/citations/20210026013/downloads/Quick_%20Chapter5_Cryovolcanism_13Jun2021.docx.pdf}}</ref>

'''Sublimation plumes''' are jets of sublimated volatiles and dust from shallow sources under icy surfaces. Known examples include the CO<sub>2</sub> jets on [[Mars]],<ref name="THEMIS2"/> and the [[nitrogen]] eruptions on [[Neptune]]'s moon [[Triton (moon)|Triton]].<ref name=shoemaker/>

On Mars [[carbon dioxide]] jets are believed to occur in the southern polar region of Mars during spring, as a layer of [[dry ice]] accumulated over winter is warmed by the sun. Although these jets have not yet been directly observed, they leave evidence visible from orbit in the form of dark spots and lighter fans atop the dry ice. These features consist primarily of sand and dust blown out by the outbursts, as well as spider-like patterns of channels created below the ice by the rapid flow of CO<sub>2</sub> gas.<ref name="THEMIS2">{{cite web |last=Burnham |first=Robert |date=16 August 2006 |title=Gas jet plumes unveil mystery of 'spiders' on Mars |url=http://www.asu.edu/news/stories/200608/20060818_marsplumes.htm |access-date=29 August 2009 |work=[[Arizona State University]] web site}}</ref> There are a plethora of theories to explain the eruptions, including heating from sunlight, chemical reactions, or even biological activity.<ref>{{Cite journal |last1=Horváth |first1=A. |last2=Gánti |first2=T. |last3=Gesztesi |first3=A. |last4=Bérczi |first4=Sz. |last5=Szathmáry |first5=E. |date=1 March 2001 |title=Probable Evidences of Recent Biological Activity on Mars: Appearance and Growing of Dark Dune Spots in the South Polar Region |url=https://ui.adsabs.harvard.edu/abs/2001LPI....32.1543H |journal=Lunar and Planetary Science |pages=1543 |bibcode=2001LPI....32.1543H}}</ref>

Triton was found to have [[Triton (moon)#Cryovolcanism|active eruptions]] of nitrogen and dust by ''[[Voyager 2]]'' when it flew past the moon in 1989. These plumes were up to 8{{Spaces}}km high, where winds would blow them up to 150{{Spaces}}km downwind, creating long, dark streaks across the otherwise bright south polar ice cap.<ref name=shoemaker>{{cite journal |doi=10.1126/science.250.4979.410 |pmid=17793016 |title=Triton's Geyser-Like Plumes: Discovery and Basic Characterization |journal=Science |volume=250 |issue=4979 |pages=410–415 |year=1990 |last1=Soderblom |first1=L. A. |last2=Kieffer |first2=S. W. |last3=Becker |first3=T. L. |last4=Brown |first4=R. H. |last5=Cook |first5=A. F. |last6=Hansen |first6=C. J. |last7=Johnson |first7=T. V. |last8=Kirk |first8=R. L. |last9=Shoemaker |first9=E. M. |bibcode=1990Sci...250..410S |s2cid=1948948}} </ref> There are various theories as to what drives the activity on Triton, such as solar heating through transparent ice,<ref name="harv2">{{cite conference |last=Kirk |first=RL |url=http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?db_key=AST&bibcode=1990LPI....21..633K&letter=.&classic=YES&defaultprint=YES&whole_paper=YES&page=633&epage=633&send=Send+PDF&filetype=.pdf |title=Thermal Models of Insolation-driven Nitrogen Geysers on Triton |conference=LPSC 22 |year=1990 |bibcode=1990LPI....21..633K |access-date=8 April 2008}}</ref> cryovolcanism, or basal heating of nitrogen ice sheets.<ref>{{Cite journal |last1=Hofgartner |first1=Jason D. |last2=Birch |first2=Samuel P. D. |last3=Castillo |first3=Julie |last4=Grundy |first4=Will M. |last5=Hansen |first5=Candice J. |last6=Hayes |first6=Alexander G. |last7=Howett |first7=Carly J. A. |last8=Hurford |first8=Terry A. |last9=Martin |first9=Emily S. |last10=Mitchell |first10=Karl L. |last11=Nordheim |first11=Tom A. |last12=Poston |first12=Michael J. |last13=Prockter |first13=Louise M. |last14=Quick |first14=Lynnae C. |last15=Schenk |first15=Paul |display-authors=4 |date=15 March 2022 |title=Hypotheses for Triton's plumes: New analyses and future remote sensing tests |url=https://www.sciencedirect.com/science/article/pii/S0019103521004796 |journal=Icarus |volume=375 |pages=114835 |doi=10.1016/j.icarus.2021.114835 |issn=0019-1035 |arxiv=2112.04627 |bibcode=2022Icar..37514835H}}</ref>

'''Cryovolcanic plumes''' or '''cryogeysers''' generally refer to large-scale eruptions of predominantly [[Water vapor|water vapour]] from active cryovolcanic features on certain [[icy moon]]s. Such plumes occur on [[Saturn]]'s moon [[Enceladus]]<ref name="Porco Helfenstein et al. 20062"/> and [[Jupiter]]'s moon [[Europa (moon)|Europa]].<ref name="NASA-20131212-EU2"/>

Plumes of water vapour, together with ice particles and smaller amounts of other components (such as [[carbon dioxide]], [[nitrogen]], [[ammonia]], [[hydrocarbon]]s and [[silicate]]s), have been observed erupting from vents associated with the "[[Tiger Stripes (Enceladus)|tiger stripes]]" in the south polar region of Enceladus by the ''[[Cassini–Huygens|Cassini]]'' orbiter. These plumes are the source of the material in Saturn's [[Rings of Saturn#E Ring|E ring]]. The mechanism which causes these eruptions are generated remains uncertain, as well as to what extent they are physically linked to Enceladus' [[subsurface ocean]], but they are believed to be powered at least in part by [[Tidal acceleration#Tidal heating|tidal heating]].<ref name="Porco Helfenstein et al. 20062">{{cite journal |last1=Porco |first1=C. C. |author-link1=Carolyn Porco |last2=Helfenstein |first2=P. |last3=Thomas |first3=P. C. |last4=Ingersoll |first4=A. P. |last5=Wisdom |first5=J. |last6=West |first6=R. |last7=Neukum |first7=G. |last8=Denk |first8=T. |last9=Wagner |first9=R. |display-authors=4 |date=10 March 2006 |title=Cassini Observes the Active South Pole of Enceladus |url=https://authors.library.caltech.edu/36593/ |journal=Science |volume=311 |issue=5766 |pages=1393–1401 |bibcode=2006Sci...311.1393P |doi=10.1126/science.1123013 |pmid=16527964 |s2cid=6976648 |ref={{sfnRef|Porco Helfenstein et al. 2006}}}}</ref> ''Cassini'' flew through these plumes several times, allowing direct analysis of water from inside another solar system body for the first time.<ref>{{Cite journal |last1=Waite |first1=J. Hunter |last2=Combi |first2=Michael R. |last3=Ip |first3=Wing-Huen |last4=Cravens |first4=Thomas E. |last5=McNutt |first5=Ralph L. |last6=Kasprzak |first6=Wayne |last7=Yelle |first7=Roger |last8=Luhmann |first8=Janet |last9=Niemann |first9=Hasso |last10=Gell |first10=David |last11=Magee |first11=Brian |last12=Fletcher |first12=Greg |last13=Lunine |first13=Jonathan |last14=Tseng |first14=Wei-Ling |display-authors=4 |date=10 March 2006 |title=Cassini Ion and Neutral Mass Spectrometer: Enceladus Plume Composition and Structure |url=https://www.science.org/doi/10.1126/science.1121290 |journal=Science |language=en |volume=311 |issue=5766 |pages=1419–1422 |doi=10.1126/science.1121290 |pmid=16527970 |bibcode=2006Sci...311.1419W |issn=0036-8075}}</ref>

In December 2013, the [[Hubble Space Telescope]] detected water vapour plumes potentially 200{{Spaces}}km high above the south polar region of [[Europa (moon)|Europa]].<ref name="NASA-20131212-EU2">{{cite web |last1=Cook |first1=Jia-Rui C. |last2=Gutro |first2=Rob |last3=Brown |first3=Dwayne |last4=Harrington |first4=J.D. |last5=Fohn |first5=Joe |date=12 December 2013 |title=Hubble Sees Evidence of Water Vapor at Jupiter Moon |url=http://www.jpl.nasa.gov/news/news.php?release=2013-363 |work=NASA}}</ref> Re-examination of ''[[Galileo (spacecraft)|Galileo]]'' data also suggested that it may have flown through a plume during a flyby in 1997.<ref>{{Cite journal |last1=Jia |first1=Xianzhe |last2=Kivelson |first2=Margaret G. |last3=Khurana |first3=Krishan K. |last4=Kurth |first4=William S. |date=June 2018 |title=Evidence of a plume on Europa from Galileo magnetic and plasma wave signatures |url=https://www.nature.com/articles/s41550-018-0450-z |journal=Nature Astronomy |language=en |volume=2 |issue=6 |pages=459–464 |doi=10.1038/s41550-018-0450-z |bibcode=2018NatAs...2..459J |issn=2397-3366}}</ref> Water was also detected by the [[Keck Observatory]] in 2016, announced in a 2019 [[Nature (journal)|Nature]] article speculating the cause to be a cryovolcanic eruption.<ref>{{Cite journal |last1=Paganini |first1=L. |last2=Villanueva |first2=G. L. |last3=Roth |first3=L. |last4=Mandell |first4=A. M. |last5=Hurford |first5=T. A. |last6=Retherford |first6=K. D. |last7=Mumma |first7=M. J. |date=March 2020 |title=A measurement of water vapour amid a largely quiescent environment on Europa |url=https://www.nature.com/articles/s41550-019-0933-6 |journal=Natuceasere Astronomy |language=en |volume=4 |issue=3 |pages=266–272 |doi=10.1038/s41550-019-0933-6 |bibcode=2020NatAs...4..266P |issn=2397-3366}}</ref> It is thought that Europa's [[lineae]] might be venting this water vapour into space in a similar manner to the "tiger stripes" of Enceladus.<ref>{{cite journal |last1=Roth |first1=L |last2=Saur |first2=J |last3=Retherford |first3=KD |last4=Strobel |first4=DF |last5=Feldman |first5=PD |last6=McGrath |first6=MA |last7=Nimmo |first7=F |year=2014 |title=Transient water vapor at Europa's south pole |journal=Science |volume=343 |issue=6167 |pages=171–174 |doi=10.1126/science.1247051 |pmid=24336567 |bibcode=2014Sci...343..171R}}</ref>
{{multiple image
| direction         = horizontal
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| width1            = 250
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| image1            = Voyager 2 Triton 14bg r90ccw colorized.jpg
| image2            = Fountains of Enceladus PIA07758.jpg
| image3            = Geysers on Mars.jpg
| caption1          = Dark streaks deposited by plumes on [[Triton (moon)|Triton]]
| caption2          = Plumes erupting from [[Enceladus]]{{'}} subsurface
| caption3          = Artist's impression of the carbon dioxide jets on [[Mars]]
}}
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