{{Short description|Feature on Titan}} {{Other uses|Sotra (disambiguation)}} {{Infobox feature on celestial object |name = Sotra Patera |image = [[File:Sotra Facula.jpg|250px]] |caption = Stereoscopic map of Sotra Patera and [[Doom Mons]]. Height is exaggerated by a factor of 10. The colours are false. |type = [[Patera (planetary nomenclature)]] |coordinates = {{coord|12.5|S|39.8|W|globe:titan_type:landmark|display=inline,title}} |diameter = {{Convert|235|km|mi|abbr=on}} |eponym = [[Sotra]], [[Norway]] }}
'''Sotra Patera''' (named after [[Sotra]] island in [[Norway]]) is a prominent depression on [[Titan (moon)|Titan]], the largest [[moons of Saturn|moon of]] [[Saturn]]. It was formerly known as '''Sotra Facula'''; the current name was approved on 19 December 2012.<ref name = USGS_Sotra_Patera>{{gpn|15077|Sotra Patera}}</ref> It is a possible [[cryovolcanic]] caldera {{convert|30|km|mi|abbr=on}} across and {{convert|1.7|km|mi|abbr=on}} deep, and is immediately to the east of the largest putative cryovolcanic mountain on Titan, the {{convert|abbr=on|1.45|km|mi|2}} high [[Doom Mons]].<ref name=Lopes_2013>{{cite journal |last1=Lopes |first1=R. M. C. |authorlink=Rosaly Lopes-Gautier |last2=Kirk |first2=R. L. |last3=Mitchell |first3=K. L. |last4=LeGall |first4=A. |last5=Barnes |first5=J. W. |last6=Hayes |first6=A. |last7=Kargel |first7=J. |last8=Wye |first8=L. |last9=Radebaugh |first9=J. |last10=Stofan |first10=E. R. |last11=Janssen|first11=M. A. |last12=Neish |first12=C. D. |last13=Wall |first13=S. D. |last14=Wood |first14=C. A. |last15=Lunine |first15=Jonathan I. |author-link15=Jonathan Lunine |last16=Malaska |first16=M. J.|title=Cryovolcanism on Titan: New results from Cassini RADAR and VIMS |journal=Journal of Geophysical Research: Planets |volume=118 |issue=3 |pages=416–435 |date=19 March 2013 |doi=10.1002/jgre.20062 |bibcode=2013JGRE..118..416L |url=https://hal.archives-ouvertes.fr/hal-00807740/file/Lopes_et_al-2013-Journal_of_Geophysical_Research__Planets.pdf |doi-access=free }}</ref> Sotra Patera is the deepest known pit on Titan.<ref name=Lopes_2013 />
The ice volcano or cryovolcano Doom Mons forms a roughly circular mountain measuring about {{convert|65|km|mi}} across. It has two peaks standing about {{convert|1000|m|ft}} and {{convert|1450|m|ft}} high with multiple craters, with Sotra Patera at {{convert|1700|m|ft}} being the deepest. Finger-like flows are visible on the flanks of the mountain, measuring perhaps {{convert|100|m|ft}} thick.<ref name="NASA statement">"[http://saturn.jpl.nasa.gov/news/newsreleases/newsrelease20101214/ Cassini Spots Potential Ice Volcano on Saturn Moon]". NASA, December 14, 2010</ref><ref name="NatGeo">{{cite web | last = Lovett | first = Richard A. | title = Saturn Moon Has Ice Volcano—And Maybe Life? | work = National Geographic News | publisher = | date = 2010-12-15 | url = http://news.nationalgeographic.com/news/2010/12/101215-saturn-moon-titan-ice-volcano-nasa-science-pictures/ | archive-url = https://web.archive.org/web/20101217154625/http://news.nationalgeographic.com/news/2010/12/101215-saturn-moon-titan-ice-volcano-nasa-science-pictures/ | url-status = dead | archive-date = December 17, 2010 | format = | accessdate = 2012-12-08}}</ref>
[[File:Sotra Facula global view.jpg|left|thumb|Global view of Titan showing the location of Sotra Patera]] The ''[[Cassini–Huygens]]'' mission has mapped Sotra Patera using the Cassini orbiter's onboard radar instrument and the visual and infrared mapping spectrometer. An earlier survey of the region in 2004 revealed a circular bright spot, or ''facula'', which was nicknamed "The Rose". A subsequent flyby by Cassini re-surveyed the region from a different angle, enabling members of the [[US Geological Survey]] [[Astrogeology]] Science Center to generate [[stereoscopic]] mapping of Sotra Patera and the surrounding area. Researchers also discovered at least two more mountains and another big crater, forming a chain of mountains several hundred kilometers long flanked by lava-covered lowlands.<ref name="NatGeo" />
With Doom Mons, Sotra Patera is regarded as "the very best evidence, by far, for volcanic topography anywhere documented on an icy satellite", according to planetary scientist Jeffrey Kargel of the [[University of Arizona]]. It has been compared with terrestrial volcanoes such as [[Mount Etna|Etna]], [[Laki]] and volcanic cones near [[Flagstaff, Arizona]]. There is as yet no evidence of current activity, but researchers plan to monitor the area for changes.<ref name="NASA statement" />
It is unclear what might have been erupted from Sotra Patera—possibly water mixed with [[ammonium]], or more exotic [[hydrocarbon]] compounds such as [[polyethylene]], [[paraffin wax]]es or [[Bitumen|asphalt]].<ref name="NatGeo" /><ref name="SciAm">Castelvecchi, Davide. "[http://www.scientificamerican.com/article.cfm?id=titan-spews-discovery Titan Spews: Discovery of Cold Volcanoes on Saturnian Moon May Solve Methane Mystery]". ''Scientific American'', December 16, 2010</ref> The eruptions may also have brought [[methane]] to the surface. Titan's dense methane atmosphere is constantly being broken down by sunlight in the upper atmosphere through [[photolysis]]; cryovolcanism may therefore explain how the atmosphere is being replenished.<ref name="SciAm" />
The eruptions of Sotra Patera are presumed to originate in a layer of liquid water lying below Titan's icy crust. The mountain's heavily cratered appearance indicates that it must have erupted with considerable force, but the precise mechanism by which this happened is not certain. Liquid water is ordinarily denser than ice but it is possible that the water's density may be reduced by mixing with other substances, such as [[ammonia]], allowing it to force its way to the surface. Alternatively, some other mechanism such as the underground formation of methane bubbles or a build-up of tectonic pressure may be responsible.<ref name="SciAm" />
==References==
{{reflist}}
{{Titan}}
[[Category:Surface features of Titan (moon)]] [[Category:Extraterrestrial volcanoes]]