Editing Saturn (section)

=== Internal structure ===
[[File:Saturn diagram.svg|thumb|upright=1.5|Diagram of Saturn, to scale|left]]Despite consisting mostly of hydrogen and helium, most of Saturn's mass is not in the [[gas]] [[phase (matter)|phase]], because hydrogen becomes a [[ideal solution|non-ideal liquid]] when the density is above {{val|0.01|u=g/cm3}}, which is reached at a radius containing 99.9% of Saturn's mass. The temperature, pressure, and density inside Saturn all rise steadily toward the core, which causes hydrogen to be a metal in the deeper layers.<ref name=ssr152_1_423/>

Standard planetary models suggest that the interior of Saturn is similar to that of Jupiter, having a small rocky core surrounded by hydrogen and helium, with trace amounts of various [[Volatile (astrogeology)|volatiles]].<ref name=guillot_et_al2009/> Analysis of the distortion shows that Saturn is substantially more centrally condensed than [[Jupiter]] and therefore contains much more material denser than [[hydrogen]] near its center. Saturn's central regions are about 50% hydrogen by mass, and Jupiter's are about 67% hydrogen.<ref>{{Cite web |title=Saturn - The interior {{!}} Britannica |url=https://www.britannica.com/place/Saturn-planet/The-interior |access-date=14 April 2022 |website=www.britannica.com |language=en}}</ref>

This core is similar in composition to Earth, but is more dense. The examination of Saturn's [[gravitational moment]], in combination with physical models of the interior, has allowed constraints to be placed on the mass of Saturn's core. In 2004, scientists estimated that the core must be 9–22 times the mass of Earth,<ref name="science305_5689_1414" /><ref name="apj609_2_1170" /> which corresponds to a diameter of about {{Convert|25000|km|abbr=on}}.<ref>{{cite web |url=https://www.bbc.co.uk/dna/h2g2/A383960 |title=Saturn |publisher=BBC |access-date=19 July 2011 |date=2000 |archive-url=https://web.archive.org/web/20110101024556/http://www.bbc.co.uk/dna/h2g2/A383960 |archive-date=1 January 2011 |url-status=live }}</ref> However, measurements of Saturn's rings suggest a much more diffuse core, with a mass equal to about 17 Earths and a radius equal to about 60% of Saturn's entire radius.<ref>{{cite journal |last1=Mankovich |first1=Christopher R. |last2=Fuller |first2=Jim |title=A diffuse core in Saturn revealed by ring seismology |url=https://www.nature.com/articles/s41550-021-01448-3 |journal=Nature Astronomy |year=2021 |volume=5 |issue=11 |pages=1103–1109 |doi=10.1038/s41550-021-01448-3 |arxiv=2104.13385 |bibcode=2021NatAs...5.1103M |s2cid=233423431 |access-date=22 August 2021 |archive-date=20 August 2021 |archive-url=https://web.archive.org/web/20210820195416/https://www.nature.com/articles/s41550-021-01448-3 |url-status=live }}</ref> This is surrounded by a thicker, liquid [[metallic hydrogen]] layer, followed by a liquid layer of helium-saturated [[molecular hydrogen]], which gradually transitions to a gas as altitude increases. The outermost layer spans about {{Convert|1000|km|abbr=on}} and consists of gas.<ref name="faure_mensing2007" /><ref name="NMM Saturn" /><ref>{{cite web |url=http://www.windows2universe.org/saturn/interior/S_int_structure_overview.html |title=Structure of Saturn's Interior |publisher=Windows to the Universe |access-date=19 July 2011 |archive-url=https://web.archive.org/web/20110917140427/http://www.windows2universe.org/saturn/interior/S_int_structure_overview.html |archive-date=17 September 2011 |url-status=dead }}</ref>

Saturn has a hot interior, reaching {{Convert|11700|C}} at its core, and radiates 2.5 times more energy into space than it receives from the Sun. Jupiter's [[thermal energy]] is generated by the [[Kelvin–Helmholtz mechanism]] of slow [[gravitational compression]]; but such a process alone may not be sufficient to explain heat production for Saturn, because it is less massive. An alternative or additional mechanism may be the generation of heat through the "raining out" of droplets of helium deep in Saturn's interior. As the droplets descend through the lower-density hydrogen, the process releases heat by [[friction]] and leaves Saturn's outer layers depleted of helium.<ref name=de_pater_lissauer2010/><ref name=nasa_saturn/> These descending droplets may have accumulated into a helium shell surrounding the core.<ref name=guillot_et_al2009/> Rainfalls of [[diamond]]s have been suggested to occur within Saturn, as well as in Jupiter<ref name="SC-20131009">{{cite news |last=Kramer |first=Miriam |title=Diamond Rain May Fill Skies of Jupiter and Saturn |url=https://www.space.com/23135-diamond-rain-jupiter-saturn.html |date=9 October 2013 |work=[[Space.com]] |access-date=27 August 2017 |archive-date=27 August 2017 |archive-url=https://web.archive.org/web/20170827171415/https://www.space.com/23135-diamond-rain-jupiter-saturn.html |url-status=live }}</ref> and [[ice giant]]s Uranus and Neptune.<ref name="WP-20170825">{{cite news |last=Kaplan |first=Sarah |title=It rains solid diamonds on Uranus and Neptune |url=https://www.washingtonpost.com/news/speaking-of-science/wp/2017/08/25/it-rains-solid-diamonds-on-uranus-and-neptune/ |date=25 August 2017 |newspaper=[[The Washington Post]] |access-date=27 August 2017 |archive-date=27 August 2017 |archive-url=https://web.archive.org/web/20170827011901/https://www.washingtonpost.com/news/speaking-of-science/wp/2017/08/25/it-rains-solid-diamonds-on-uranus-and-neptune/ |url-status=live }}</ref>