Editing Pluto (section)

== Geology ==
{{Main|Geology of Pluto|Geography of Pluto}}

=== Surface ===
[[File:Pluto’s Heart - Like a Cosmic Lava Lamp.jpg|thumb|Sputnik Planitia is covered with churning nitrogen ice "cells" that are geologically young and turning over due to [[Convection cell|convection]].]]
The plains on Pluto's surface are composed of more than 98 percent [[nitrogen ice]], with traces of methane and [[carbon monoxide]].<ref name="tobias" /> [[Nitrogen]] and carbon monoxide are most abundant on the anti-Charon face of Pluto (around 180° longitude, where [[Tombaugh Regio]]'s western lobe, [[Sputnik Planitia]], is located), whereas methane is most abundant near 300° east.<ref name=Grundy_2013 /> The mountains are made of water ice.<ref name="drake-natgeo">{{cite magazine | url = http://news.nationalgeographic.com/2015/11/151109-astronomy-pluto-nasa-new-horizons-volcano-moons-science/| archive-url = https://web.archive.org/web/20151113013310/http://news.nationalgeographic.com/2015/11/151109-astronomy-pluto-nasa-new-horizons-volcano-moons-science/| url-status = dead| archive-date = November 13, 2015| title = Floating Mountains on Pluto – You Can't Make This Stuff Up| last = Drake| first = Nadia| author-link = Nadia Drake | date = November 9, 2015| magazine = [[National Geographic]]| access-date = December 23, 2016}}</ref> Pluto's surface is quite varied, with large differences in both brightness and color.<ref name="Buie_2010 light curve" /> Pluto is one of the most contrastive bodies in the Solar System, with as much contrast as [[Saturn]]'s moon [[Iapetus (moon)|Iapetus]].<ref name="Buie_web_map" /> The color varies from charcoal black, to dark orange and white.<ref name="Hubble2010" /> Pluto's color is more similar to that of [[Io (moon)|Io]] with slightly more orange and significantly less red than [[Mars]].<ref name="Buie_2010 surface-maps" /> [[Geography of Pluto|Notable geographical features]] include Tombaugh Regio, or the "Heart" (a large bright area on the side opposite Charon), [[Belton Regio]],<ref name = "Pluto System after New Horizons"/> or the "Whale" (a large dark area on the trailing hemisphere), and the "[[Brass Knuckles (Pluto)|Brass Knuckles]]" (a series of equatorial dark areas on the leading hemisphere).

Sputnik Planitia, the western lobe of the "Heart", is a 1,000&nbsp;km-wide basin of frozen nitrogen and carbon monoxide ices, divided into polygonal cells, which are interpreted as [[convection cell]]s that carry floating blocks of water ice crust and [[Sublimation (phase transition)|sublimation]] pits towards their margins;<ref name="lakdawalla-DPS-2016-10-26">{{cite web| url = http://www.planetary.org/blogs/emily-lakdawalla/2016/10251718-dpsepsc-new-horizons-pluto.html| title = DPS/EPSC update on New Horizons at the Pluto system and beyond| last = Lakdawalla| first = Emily| author-link = Emily Lakdawalla| date = October 26, 2016| publisher = [[The Planetary Society]]| access-date = October 26, 2016| archive-date = October 8, 2018| archive-url = https://web.archive.org/web/20181008021643/http://www.planetary.org/blogs/emily-lakdawalla/2016/10251718-dpsepsc-new-horizons-pluto.html| url-status = live}}</ref><ref name="McKinnon2016">{{cite journal|last1=McKinnon|first1=W. B.|last2=Nimmo|first2= F.|last3=Wong|first3= T.|last4= Schenk|first4=P. M.|last5=White|first5=O. L.|last6=Roberts|first6=J. H.|last7=Moore|first7=J. M.|last8=Spencer|first8=J. R.|last9=Howard|first9=A. D.|last10=Umurhan|first10=O. M.|last11= Stern|first11=S. A.|last12=Weaver|first12=H. A.|last13= Olkin|first13=C. B.|last14=Young|first14=L. A.|last15= Smith|first15=K. E.|last16=Beyer|first16= R.|last17= Buie|first17= M.|last18=Buratti|first18= B.|last19= Cheng|first19= A.|last20=Cruikshank|first20=D.|last21=Dalle Ore|first21= C.|last22= Gladstone|first22= R.|last23= Grundy|first23= W.|last24=Lauer|first24=T.|last25=Linscott|first25= I.|last26= Parker|first26= J.|last27=Porter|first27= S.|last28= Reitsema|first28= H.|last29=Reuter|first29= D.|last30= Robbins|first30= S.|last31= Showalter|first31= M.|last32= Singer|first32= K.|last33=Strobel|first33= D.|last34= Summers|first34= M.|last35= Tyler|first35= L.|last36= Banks|first36= M.|last37=Barnouin|first37= O.|last38= Bray|first38= V.|last39= Carcich|first39= B.|last40=Chaikin|first40= A.|last41= Chavez|first41=C.|last42= Conrad|first42= C.|last43= Hamilton|first43= D.|last44= Howett|first44= C.|last45=Hofgartner|first45= J.|last46= Kammer|first46= J.|last47= Lisse|first47= C.|last48= Marcotte|first48= A.|last49=Parker|first49= A.|last50= Retherford|first50= K.|last51=Saina|first51= M.|last52= Runyon|first52= K.|last53=Schindhelm|first53= E.|last54= Stansberry|first54= J.|last55= Steffl|first55= A.|last56= Stryk|first56=T.|last57=Throop|first57=H.|last58=Tsang|first58=C.|last59=Verbiscer|first59=A.|last60=Winters|first60=H.|last61=Zangari|first61=A.|display-authors=5|title=Convection in a volatile nitrogen-ice-rich layer drives Pluto's geological vigour|journal= Nature|volume=534|issue= 7605|date=June 1, 2016|pages= 82–85|doi= 10.1038/nature18289|pmid=27251279|bibcode = 2016Natur.534...82M |arxiv=1903.05571|s2cid=30903520}}</ref><ref name="Trowbridge2016">{{cite journal|last1=Trowbridge|first1=A. J.|last2= Melosh|first2=H. J.|last3= Steckloff|first3= J. K.|last4=Freed|first4=A. M.|title=Vigorous convection as the explanation for Pluto's polygonal terrain|journal= Nature|volume= 534|issue=7605|date= June 1, 2016|pages=79–81|doi=10.1038/nature18016|pmid=27251278|bibcode = 2016Natur.534...79T |s2cid=6743360 }}</ref> there are obvious signs of glacial flows both into and out of the basin.<ref name="Pluto updates">{{cite web| url = http://www.planetary.org/blogs/emily-lakdawalla/2015/12211538-pluto-updates-from-agu.html| title = Pluto updates from AGU and DPS: Pretty pictures from a confusing world| last = Lakdawalla| first = Emily| author-link = Emily Lakdawalla| date = December 21, 2015| publisher = [[The Planetary Society]]| access-date = January 24, 2016| archive-date = December 24, 2015| archive-url = https://web.archive.org/web/20151224193036/http://www.planetary.org/blogs/emily-lakdawalla/2015/12211538-pluto-updates-from-agu.html| url-status = live}}</ref><ref name="Umurhan2016-01-08">{{cite web
| url = https://blogs.nasa.gov/pluto/2016/01/08/probing-the-mysterious-glacial-flow-on-plutos-frozen-heart/
| title = Probing the Mysterious Glacial Flow on Pluto's Frozen 'Heart'
| last = Umurhan
| first = O.
| date = January 8, 2016
| website = blogs.nasa.gov
| publisher = NASA
| access-date = January 24, 2016
| archive-date = April 19, 2016
| archive-url = https://web.archive.org/web/20160419182828/https://blogs.nasa.gov/pluto/2016/01/08/probing-the-mysterious-glacial-flow-on-plutos-frozen-heart/
| url-status = live
}}</ref> It has no craters that were visible to ''New Horizons'', indicating that its surface is less than 10&nbsp;million years old.<ref name="Marchis2016">{{cite journal|last1=Marchis|first1=F.|last2=Trilling|first2=D. E.|title=The Surface Age of Sputnik Planum, Pluto, Must Be Less than 10 Million Years|journal=PLOS ONE|volume= 11|issue=1|date= January 20, 2016|pages= e0147386|doi= 10.1371/journal.pone.0147386|arxiv = 1601.02833 |bibcode = 2016PLoSO..1147386T|pmid=26790001|pmc=4720356|doi-access=free}}</ref> Latest studies have shown that the surface has an age of {{val|180000|-90000|+40000}} years.<ref name="LPSC2017Buhler">{{cite conference|last1=Buhler|first1=P. B.|last2=Ingersoll|first2=A. P.|url=https://www.hou.usra.edu/meetings/lpsc2017/pdf/1746.pdf|title=Sublimation pit distribution indicates convection cell surface velocity of ~10 centimeters per year in Sputnik Planitia, Pluto|book-title=48th Lunar and Planetary Science Conference|date=March 23, 2017|access-date=May 11, 2017|archive-date=August 13, 2017|archive-url=https://web.archive.org/web/20170813010426/https://www.hou.usra.edu/meetings/lpsc2017/pdf/1746.pdf|url-status=live}}</ref>
The New Horizons science team summarized initial findings as "Pluto displays a surprisingly wide variety of geological landforms, including those resulting from [[glaciological]] and surface–atmosphere interactions as well as impact, [[plate tectonics|tectonic]], possible [[cryovolcanic]], and [[mass wasting|mass-wasting]] processes."<ref name="Stern2015" />

In Western parts of Sputnik Planitia there are fields of [[transverse dunes]] formed by the winds blowing from the center of Sputnik Planitia in the direction of surrounding mountains. The dune wavelengths are in the range of 0.4–1&nbsp;km and likely consist of methane particles 200–300&nbsp;μm in size.<ref name="Brown2018">{{cite journal|doi=10.1126/science.aao2975|pmid=29853681|title=Dunes on Pluto|journal=Science|volume=360|issue=6392|pages=992–997|year=2018|last1=Telfer|first1=Matt W|last2=Parteli|first2=Eric J. R|last3=Radebaugh|first3=Jani|last4=Beyer|first4=Ross A|last5=Bertrand|first5=Tanguy|last6=Forget|first6=François|last7=Nimmo|first7=Francis|last8=Grundy|first8=Will M|last9=Moore|first9=Jeffrey M|last10=Stern|first10=S. Alan|last11=Spencer|first11=John|last12=Lauer|first12=Tod R|last13=Earle|first13=Alissa M|last14=Binzel|first14=Richard P|last15=Weaver|first15=Hal A|last16=Olkin|first16=Cathy B|last17=Young|first17=Leslie A|last18=Ennico|first18=Kimberly|last19=Runyon|first19=Kirby|bibcode=2018Sci...360..992T|s2cid=44159592|url=https://pearl.plymouth.ac.uk/bitstream/handle/10026.1/11613/UoP_Deposit_Agreement%20v1.1%2020160217.pdf?sequence=2&isAllowed=y|doi-access=free|access-date=April 12, 2020|archive-date=October 23, 2020|archive-url=https://web.archive.org/web/20201023114119/https://pearl.plymouth.ac.uk/bitstream/handle/10026.1/11613/UoP_Deposit_Agreement%20v1.1%2020160217.pdf?sequence=2&isAllowed=y|url-status=live}}</ref>

<gallery mode=packed heights=160>
File:Pluto-01 Stern 03 Pluto Color TXT.jpg|Multispectral Visual Imaging Camera image of Pluto in enhanced color to bring out differences in surface composition
File:Pluto_Charon_crater_map_Robbins_Dones_2023.jpg|Distribution of numerous impact craters and basins on both Pluto and Charon. The variation in density (with none found in [[Sputnik Planitia]]) indicates a long history of varying geological activity. Precisely for this reason, the confidence of numerous craters on Pluto remain uncertain.<ref name="Robbins2023"/> The lack of craters on the left and right of each map is due to low-resolution coverage of those anti-encounter regions.
File:Pluto's Sputnik Planum geologic map (cropped).jpg|Geologic map of Sputnik Planitia and surroundings ([[:File:Pluto's Sputnik Planum geologic map - context.jpg|context]]), with [[convection cell]] margins outlined in black
NH-Pluto-WaterIceDetected-BlueRegions-Released-20151008.jpg|Regions where water ice has been detected (blue regions)
</gallery>

=== Internal structure ===
{{redirect|Life on Pluto|fiction about aliens from Pluto|Life on Pluto in fiction}}
[[File:Pluto's internal structure2.jpg|thumb|Model of the internal structure of Pluto<ref name="Hussmann2006" />{{Bulleted list|Water ice crust|Liquid water ocean|Silicate core}}]]
Pluto's density is {{val|1.853|0.004|u=g/cm3}}.<ref name="Brozovic2024"/> Because the decay of radioactive elements would eventually heat the ices enough for the rock to separate from them, scientists expect that Pluto's internal structure is differentiated, with the rocky material having settled into a dense [[Core (geology)|core]] surrounded by a [[mantle (geology)|mantle]] of water ice. The pre–''New Horizons'' estimate for the diameter of the core is {{val|1,700|u=km}}, 70% of Pluto's diameter.<ref name="Hussmann2006" /> 
It is possible that such heating continues, creating a [[subsurface ocean]] of liquid water {{nowrap|100 to 180 km}} thick at the core–mantle boundary.<ref name="Hussmann2006" /><ref name="pluto.jhuapl Inside Story" /><ref name="Sci Am 2017">[https://www.scientificamerican.com/article/overlooked-ocean-worlds-fill-the-outer-solar-system/ Overlooked Ocean Worlds Fill the Outer Solar System] {{Webarchive|url=https://web.archive.org/web/20181226133924/https://www.scientificamerican.com/article/overlooked-ocean-worlds-fill-the-outer-solar-system/ |date=December 26, 2018 }}.  John Wenz, ''Scientific American''. October 4, 2017.</ref> In September 2016, scientists at [[Brown University]] simulated the impact thought to have formed [[Sputnik Planitia]], and showed that it might have been the result of liquid water upweling from below after the collision, implying the existence of a subsurface ocean at least 100&nbsp;km deep.<ref>{{cite magazine|title=An Incredibly Deep Ocean Could Be Hiding Beneath Pluto's Icy Heart|author=Samantha Cole|url=http://www.popsci.com/an-incredibly-deep-ocean-could-be-hiding-beneath-plutos-icy-heart|magazine=Popular Science|access-date=September 24, 2016|archive-date=September 27, 2016|archive-url=https://web.archive.org/web/20160927112125/http://www.popsci.com/an-incredibly-deep-ocean-could-be-hiding-beneath-plutos-icy-heart|url-status=live}}</ref> In June 2020, astronomers reported evidence that Pluto may have had a [[Extraterrestrial liquid water|subsurface ocean]], and consequently may have been [[Planetary habitability|habitable]], when it was first formed.<ref name="INV-20200622">{{cite news |last=Rabie |first=Passant |title=New Evidence Suggests Something Strange and Surprising about Pluto&nbsp;— The findings will make scientists rethink the habitability of Kuiper Belt objects. |url=https://www.inverse.com/science/pluto-hot-star |date=June 22, 2020 |work=[[Inverse (website)|Inverse]] |access-date=June 23, 2020 |archive-date=June 23, 2020 |archive-url=https://web.archive.org/web/20200623071829/https://www.inverse.com/science/pluto-hot-star |url-status=live }}</ref><ref name="NGS-20200622">{{cite journal |author=Bierson, Carver |display-authors=et al. |title=Evidence for a hot start and early ocean formation on Pluto |url=https://www.nature.com/articles/s41561-020-0595-0 |date=June 22, 2020 |journal=[[Nature Geoscience]] |volume=769 |issue=7 |pages=468–472 |doi=10.1038/s41561-020-0595-0 |bibcode=2020NatGe..13..468B |s2cid=219976751 |access-date=June 23, 2020 |url-access=subscription |archive-date=June 22, 2020 |archive-url=https://web.archive.org/web/20200622201613/https://www.nature.com/articles/s41561-020-0595-0 |url-status=live }}</ref> In March 2022, a team of researchers proposed that the mountains [[Wright Mons]] and [[Piccard Mons]] are actually a merger of many smaller cryovolcanic domes, suggesting a source of heat on the body at levels previously thought not possible.<ref>{{cite journal |title=Large-scale cryovolcanic resurfacing on Pluto |first=Kelsi N. |last=Singer |journal=[[Nature Communications]] |date=March 29, 2022 |volume=13 |issue=1 |page=1542 |doi=10.1038/s41467-022-29056-3 |pmid=35351895 |pmc=8964750 |arxiv=2207.06557 |bibcode=2022NatCo..13.1542S }}</ref>