List of gravitationally rounded objects of the Solar System#Planets
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This is a list of most likely gravitationally rounded objects (GRO) of the Solar System, which are objects that have a rounded, ellipsoidal shape due to their own gravity (but are not necessarily in hydrostatic equilibrium). Apart from the Sun itself, these objects qualify as planets according to common geophysical definitions of that term. The radii of these objects range over three orders of magnitude, from planetary-mass objects like dwarf planets and some moons to the planets and the Sun. This list does not include small Solar System bodies, but it does include a sample of possible planetary-mass objects whose shapes have yet to be determined. The Sun's orbital characteristics are listed in relation to the Galactic Center, while all other objects are listed in order of their distance from the Sun.
Star
{{Main|Sun}}
The Sun is a G-type main-sequence star. It contains almost 99.9% of all the mass in the Solar System.{{cite journal |first=Michael Mark |last=Woolfson |author-link=Michael Woolfson |title=The Origin and Evolution of the Solar System |doi=10.1046/j.1468-4004.2000.00012.x |date=2000 |journal=Astronomy & Geophysics |volume=41 |issue=1 |pages=1.12–1.19 |bibcode=2000A&G....41a..12W |doi-access=free}}
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| colspan="2" rowspan=2 |
! style="background: yellow;" | Sun[http://solarsystem.nasa.gov/planets/profile.cfm?Object=Sun&Display=Facts&System=Metric NASA Solar System exploration Sun factsheet] {{webarchive |url=https://web.archive.org/web/20080102034758/http://solarsystem.nasa.gov/planets/profile.cfm?Object=Sun&Display=Facts&System=Metric |date=2008-01-02 }} and [http://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html NASA Sun factsheet] {{Webarchive|url=https://web.archive.org/web/20100715200549/http://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html |date=2010-07-15 }} NASA Retrieved 2008-11-17 (unless otherwise cited){{Cite web|title=By the Numbers {{!}} Sun - NASA Solar System Exploration|url=https://solarsystem.nasa.gov/solar-system/sun/by-the-numbers/|website=NASA|date=14 November 2017 |access-date=16 June 2021|archive-date=23 May 2019|archive-url=https://web.archive.org/web/20190523230455/https://solarsystem.nasa.gov/solar-system/sun/by-the-numbers/|url-status=live}} |
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| colspan="2" style="background: #fffdd0;" | Symbol (image){{ref label|Q|q|none}}
| style="background: yellow;" | 20px |
| colspan="2" style="background: #fffdd0;" | Symbol (Unicode){{ref label|Q|q|none}}
| style="background: yellow;" | ☉ |
| colspan="2" style="background: #fffdd0;" | Discovery year
| style="background: yellow;" | Prehistoric |
| style="background: #fffdd0;" | Mean distance from the Galactic Center | style="background: #fffdd0;" | km | style="background: yellow;" | ≈ 2.5{{e|17}} |
| style="background: #fffdd0;" | Mean radius
| style="background: #fffdd0;" | km | style="background: yellow;" | 695,508 |
| style="background: #fffdd0;" | Surface area
| style="background: #fffdd0;" | km2 | style="background: yellow;" | 6.0877{{e|12}} |
| style="background: #fffdd0;" | Volume
| style="background: #fffdd0;" | km3 | style="background: yellow;" | 1.4122{{e|18}} |
| style="background: #fffdd0;" | Mass
| style="background: #fffdd0;" | kg | style="background: yellow;" | 1.9855{{e|30}} |
| style="background: #fffdd0;" |Gravitational parameter
| style="background: #fffdd0;" |m3/s2 | style="background: yellow;" |1.327×1020 |
| style="background: #fffdd0;" | Density
| style="background: #fffdd0;" | g/cm3 | style="background: yellow;" | 1.409 |
| style="background: #fffdd0;" | Equatorial gravity
| style="background: #fffdd0;" | m/s2 | style="background: yellow;" | 274.0 |
| style="background: #fffdd0;" | Escape velocity
| style="background: #fffdd0;" | km/s | style="background: yellow;" | 617.7 |
| style="background: #fffdd0;" | Rotation period
| style="background: #fffdd0;" | days{{ref label|G|g|none}} | style="background: yellow;" | 25.38 |
| style="background: #fffdd0;" | Orbital period about Galactic Center{{cite web |url=http://hypertextbook.com/facts/2002/StacyLeong.shtml |work=The Physics Factbook (self-published) |first=Stacy |last=Leong |editor-first=Glenn |editor-last=Elert |date=2002 |title=Period of the Sun's Orbit around the Galaxy (Cosmic Year) |access-date=2008-06-26 |archive-date=7 January 2019 |archive-url=https://web.archive.org/web/20190107010909/https://hypertextbook.com/facts/2002/StacyLeong.shtml |url-status=live }}
| style="background: #fffdd0;" | million years | style="background: yellow;" | 225–250 |
| style="background: #fffdd0;" | Mean orbital speed
| style="background: #fffdd0;" | km/s | style="background: yellow;" | ≈ 220 |
| style="background: #fffdd0;" | Axial tilt{{ref label|I|i|none}} to the ecliptic
| style="background: #fffdd0;" | deg. | style="background: yellow;" | 7.25 |
| style="background: #fffdd0;" | Axial tilt{{ref label|I|i|none}} to the galactic plane
| style="background: #fffdd0;" | deg. | style="background: yellow;" | 67.23 |
| style="background: #fffdd0;" | Mean surface temperature
| style="background: #fffdd0;" | K | style="background: yellow;" | 5,778 |
| style="background: #fffdd0;" | Mean coronal temperature{{cite book |title=Encyclopedia of the Solar System |editor-first1=Lucy Ann |editor-last1=McFadden |editor-first2=Paul R. |editor-last2=Weissman |editor-first3=Torrence V. |editor-last3=Johnsson |chapter=The Sun |page=80 |first=Markus J. |last=Aschwanden |date=2007 |publisher=Academic Press }}
| style="background: #fffdd0;" | K | style="background: yellow;" | 1–2{{e|6}} |
| colspan="2" style="background: #fffdd0;" | Photospheric composition |
Planets
{{Main|Planet}}
In 2006, the International Astronomical Union (IAU) defined a planet as a body in orbit around the Sun that was large enough to have achieved hydrostatic equilibrium and to have "cleared the neighbourhood around its orbit".{{cite press release |date=2006-08-24 |publisher=International Astronomical Union |id=news release IAU0603 |title=IAU 2006 General Assembly: Result of the IAU Resolution votes |url=http://www.iau.org/news/pressreleases/detail/iau0603/ |access-date=2007-12-31 |archive-url=https://web.archive.org/web/20070103145836/http://www.iau.org/iau0603.414.0.html |archive-date=2007-01-03 }} ({{cite web |url=http://www.iau.org/iau0603.414.0.html |title=original IAU news release link |access-date=2008-10-06 |archive-url=https://web.archive.org/web/20080205210247/http://www.iau.org/iau0603.414.0.html |archive-date=2008-02-05 }}) The practical meaning of "cleared the neighborhood" is that a planet is comparatively massive enough for its gravitation to control the orbits of all objects in its vicinity. In practice, the term "hydrostatic equilibrium" is interpreted loosely. Mercury is round but not actually in hydrostatic equilibrium, but it is universally regarded as a planet nonetheless.{{cite book|first1=Sean|last1=Solomon|author-link1=Sean Solomon|first2=Larry|last2=Nittler|first3=Brian|last3=Anderson|date=20 December 2018|title=Mercury: The View after MESSENGER|series=Cambridge Planetary Science Series|number=21|url=https://books.google.com/books?id=4o92DwAAQBAJ|publisher=Cambridge University Press|pages=72–73|isbn=978-1-107-15445-2|access-date=23 September 2022|archive-date=1 March 2024|archive-url=https://web.archive.org/web/20240301162217/https://books.google.com/books?id=4o92DwAAQBAJ|url-status=live}}
According to the IAU's explicit count, there are eight planets in the Solar System; four terrestrial planets (Mercury, Venus, Earth, and Mars) and four giant planets, which can be divided further into two gas giants (Jupiter and Saturn) and two ice giants (Uranus and Neptune). When excluding the Sun, the four giant planets account for more than 99% of the mass of the Solar System.
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|+Key | style="background-color: #eeffee; vertical-align: top;"| * Terrestrial planet |
| style="background-color: #fffaee; vertical-align: top;" | ° Gas giant |
| style="background-color: #ffe6ea; vertical-align: top;"| × Ice giant |
| class="wikitable" style="text-align: center;"
! colspan="2" rowspan=2 | ! style="background: #efe;" | *Mercury{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.html |title=NASA Mercury Fact Sheet |publisher=NASA |access-date=2008-11-17 |archive-url=https://web.archive.org/web/20151106171436/http://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.html |archive-date=2015-11-06}}{{cite web |url=http://solarsystem.nasa.gov/planets/profile.cfm?Object=Mercury&Display=Facts |archive-url=https://web.archive.org/web/20040224173620/http://solarsystem.nasa.gov/planets/profile.cfm?Object=Mercury&Display=Facts |archive-date=2004-02-24 |title=NASA Solar System Exploration Factsheet |publisher=NASA |access-date=2008-11-17}}{{Cite web|title=Planets and Pluto: Physical Characteristics|url=https://ssd.jpl.nasa.gov/?planet_phys_par|website=JPL, NASA|access-date=15 June 2021|archive-date=6 May 2020|archive-url=https://web.archive.org/web/20200506001657/https://ssd.jpl.nasa.gov/?planet_phys_par|url-status=live}} ! style="background: #efe;" | *Venus{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html |title=NASA Venus Factsheet |publisher=NASA |access-date=2008-11-17 |archive-url=https://web.archive.org/web/20160308174416/http://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html |archive-date=2016-03-08 |url-status=live}}{{cite web |url=http://sse.jpl.nasa.gov/planets/profile.cfm?Object=Venus&Display=Facts&System=Metric |title=NASA Solar System Exploration Factsheet |publisher=NASA |archive-url=https://web.archive.org/web/20060929003116/http://sse.jpl.nasa.gov/planets/profile.cfm?Object=Venus&Display=Facts&System=Metric |archive-date=2006-09-29 |access-date=2008-11-17}} ! style="background: #efe;" | *Earth{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html |title=NASA Earth factsheet |publisher=NASA |access-date=2008-11-17 |archive-date=8 May 2013 |archive-url=https://web.archive.org/web/20130508021904/http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html |url-status=live }}{{cite web |url=http://sse.jpl.nasa.gov/planets/profile.cfm?Object=Earth&Display=Facts&System=Metric |title=NASA Solar System Exploration Factsheet |archive-url=https://web.archive.org/web/20090827003435/http://sse.jpl.nasa.gov/planets/profile.cfm?Object=Earth&Display=Facts&System=Metric |archive-date=2009-08-27 |publisher=NASA |access-date=2008-11-17}} ! style="background: #efe;" | *Mars{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html |title=NASA Mars Factsheet |publisher=NASA |archive-url=https://web.archive.org/web/20100612092806/http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html |archive-date=2010-06-12 |access-date=2008-11-17}}{{cite web |url=http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mars&Display=Facts&System=Metric |archive-url=https://web.archive.org/web/20040123051926/http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mars&Display=Facts&System=Metric |archive-date=2004-01-23 |title=NASA Mars Solar System Exploration Factsheet |publisher=NASA |access-date=2008-11-17}} ! style="background: #fffaee;" | °Jupiter{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/jupiterfact.html |title=NASA Jupiter factsheet |publisher=NASA |access-date=2008-11-17 |archive-url=https://web.archive.org/web/20111013042045/http://nssdc.gsfc.nasa.gov/planetary/factsheet/jupiterfact.html |archive-date=2011-10-13 |url-status=live}}{{cite web |url=http://solarsystem.nasa.gov/planets/profile.cfm?Object=Jupiter&Display=Facts |archive-url=https://web.archive.org/web/20031215141351/http://solarsystem.nasa.gov/planets/profile.cfm?Object=Jupiter&Display=Facts |archive-date=2003-12-15 |title=NASA Solar System Exploration Factsheet |publisher=NASA |access-date=2008-11-17}} ! style="background: #fffaee;" | °Saturn{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/saturnfact.html |title=NASA Saturn factsheet |publisher=NASA |archive-url=https://web.archive.org/web/20110818175309/http://nssdc.gsfc.nasa.gov/planetary/factsheet/saturnfact.html |archive-date=2011-08-18 |url-status=live |access-date=2008-11-17}}{{cite web |url=http://solarsystem.nasa.gov/planets/profile.cfm?Object=Saturn&Display=Facts |archive-url=https://web.archive.org/web/20040224191458/http://solarsystem.nasa.gov/planets/profile.cfm?Object=Saturn&Display=Facts |archive-date=2004-02-24 |title=NASA Solar System Exploration Saturn Factsheet |publisher=NASA |access-date=2008-11-17}} ! style="background: #ffe6ea;" | ×Uranus{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/uranusfact.html |title=NASA Uranus Factsheet |publisher=NASA |archive-url=https://web.archive.org/web/20110804224710/http://nssdc.gsfc.nasa.gov/planetary/factsheet/uranusfact.html |archive-date=2011-08-04 |url-status=live |access-date=2008-11-17}}{{cite web |url=http://solarsystem.nasa.gov/planets/profile.cfm?Object=Uranus&Display=Facts |archive-url=https://web.archive.org/web/20031214200402/http://solarsystem.nasa.gov/planets/profile.cfm?Object=Uranus&Display=Facts |archive-date=2003-12-14 |title=NASA Solar System Exploration Uranus Factsheet |publisher=NASA |access-date=2008-11-17}} ! style="background: #ffe6ea;" | ×Neptune{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html |title=NASA Neptune Factsheet |publisher=NASA |access-date=2008-11-17 |archive-date=1 July 2010 |archive-url=https://web.archive.org/web/20100701192119/http://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html |url-status=live }}{{cite web |url=http://solarsystem.nasa.gov/planets/profile.cfm?Object=Neptune&Display=Facts |archive-url=https://web.archive.org/web/20031215224327/http://solarsystem.nasa.gov/planets/profile.cfm?Object=Neptune&Display=Facts |archive-date=2003-12-15 |title=NASA Solar System Exploration Neptune Factsheet |publisher=NASA |access-date=2008-11-17}} |
| style="background: black;" | 76x76px
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| colspan="2" style="background: #fffdd0;" | Symbol{{ref label|Q|q|none}}
| style="background: #eeffee;" | 20px | style="background: #eeffee;" | 20px | style="background: #eeffee;" | 20px | style="background: #eeffee;" | 20px | style="background: #fffaee;" | 20px | style="background: #fffaee;" | 20px | style="background: #ffe6ea;" | 20px or 20px | style="background: #ffe6ea;" | 20px |
| colspan="2" style="background: #fffdd0;" | Symbol (Unicode){{ref label|Q|q|none}}
| style="background: #eeffee;" | ☿ | style="background: #eeffee;" | ♀ | style="background: #eeffee;" | 🜨 | style="background: #eeffee;" | ♂ | style="background: #fffaee;" | ♃ | style="background: #fffaee;" | ♄ | style="background: #ffe6ea;" | ⛢ or ♅ | style="background: #ffe6ea;" | ♆ |
| colspan="2" style="background: #fffdd0;" | Discovery year
| style="background: #eeffee;" | Prehistoric | style="background: #eeffee;" | Prehistoric | style="background: #eeffee;" | Prehistoric | style="background: #eeffee;" | Prehistoric | style="background: #fffaee;" | Prehistoric | style="background: #fffaee;" | Prehistoric | style="background: #ffe6ea;" | 1781 | style="background: #ffe6ea;" | 1846 |
| style="background: #fffdd0;" | Mean distance from the Sun | style="background: #fffdd0;" | km | style="background: #eeffee;" | 57,909,175 | style="background: #eeffee;" | 108,208,930 | style="background: #eeffee;" | 149,597,890 | style="background: #eeffee;" | 227,936,640 | style="background: #fffaee;" | 778,412,010 | style="background: #fffaee;" | 1,426,725,400 | style="background: #ffe6ea;" | 2,870,972,200 | style="background: #ffe6ea;" | 4,498,252,900 |
| style="background: #fffdd0;" | Equatorial radius
| style="background: #fffdd0;" | km | style="background: #eeffee;" | 2,440.53 | style="background: #eeffee;" | 6,051.8 | style="background: #eeffee;" | 6,378.1366 | style="background: #eeffee;" | 3,396.19 | style="background: #fffaee;" | 71,492 | style="background: #fffaee;" | 60,268 | style="background: #ffe6ea;" | 25,559 | style="background: #ffe6ea;" | 24,764 |
| style="background: #fffdd0;" | Surface area
| style="background: #fffdd0;" | km2 | style="background: #eeffee;" | 75,000,000 | style="background: #eeffee;" | 460,000,000 | style="background: #eeffee;" | 510,000,000 | style="background: #eeffee;" | 140,000,000 | style="background: #fffaee;" | 64,000,000,000 | style="background: #fffaee;" | 44,000,000,000 | style="background: #ffe6ea;" | 8,100,000,000 | style="background: #ffe6ea;" | 7,700,000,000 |
| style="background: #fffdd0;" | Volume
| style="background: #fffdd0;" | km3 | style="background: #eeffee;" | 6.083{{e|10}} | style="background: #eeffee;" | 9.28{{e|11}} | style="background: #eeffee;" | 1.083{{e|12}} | style="background: #eeffee;" | 1.6318{{e|11}} | style="background: #fffaee;" | 1.431{{e|15}} | style="background: #fffaee;" | 8.27{{e|14}} | style="background: #ffe6ea;" | 6.834{{e|13}} | style="background: #ffe6ea;" | 6.254{{e|13}} |
| style="background: #fffdd0;" | Mass
| style="background: #fffdd0;" | kg | style="background: #eeffee;" | 3.302{{e|23}} | style="background: #eeffee;" | 4.8690{{e|24}} | style="background: #eeffee;" | 5.972{{e|24}} | style="background: #eeffee;" | 6.4191{{e|23}} | style="background: #fffaee;" | 1.8987{{e|27}} | style="background: #fffaee;" | 5.6851{{e|26}} | style="background: #ffe6ea;" | 8.6849{{e|25}} | style="background: #ffe6ea;" | 1.0244{{e|26}} |
| style="background: #fffdd0;" |Gravitational parameter
| style="background: #fffdd0;" |m3/s2 | style="background: #eeffee;" |2.203×1013 | style="background: #eeffee;" |3.249×1014 | style="background: #eeffee;" |3.986×1014 | style="background: #eeffee;" |4.283×1013 | style="background: #fffaee;" |1.267×1017 | style="background: #fffaee;" |3.793×1016 | style="background: #ffe6ea;" |5.794×1015 | style="background: #ffe6ea;" |6.837×1015 |
| style="background: #fffdd0;" | Density
| style="background: #fffdd0;" | g/cm3 | style="background: #eeffee;" | 5.43 | style="background: #eeffee;" | 5.24 | style="background: #eeffee;" | 5.52 | style="background: #eeffee;" | 3.940 | style="background: #fffaee;" | 1.33 | style="background: #fffaee;" | 0.70 | style="background: #ffe6ea;" | 1.30 | style="background: #ffe6ea;" | 1.76 |
| style="background: #fffdd0;" | Equatorial gravity
| style="background: #fffdd0;" | m/s2 | style="background: #eeffee;" | 3.70 | style="background: #eeffee;" | 8.87 | style="background: #eeffee;" | 9.8 | style="background: #eeffee;" | 3.71 | style="background: #fffaee;" | 24.79 | style="background: #fffaee;" | 10.44 | style="background: #ffe6ea;" | 8.87 | style="background: #ffe6ea;" | 11.15 |
| style="background: #fffdd0;" | Escape velocity
| style="background: #fffdd0;" | km/s | style="background: #eeffee;" | 4.25 | style="background: #eeffee;" | 10.36 | style="background: #eeffee;" | 11.18 | style="background: #eeffee;" | 5.02 | style="background: #fffaee;" | 59.54 | style="background: #fffaee;" | 35.49 | style="background: #ffe6ea;" | 21.29 | style="background: #ffe6ea;" | 23.71 |
| style="background: #fffdd0;" | Rotation period{{ref label|G|g|none}}
| style="background: #fffdd0;" | days | style="background: #eeffee;" | 58.646225 | style="background: #eeffee;" | 243.0187 | style="background: #eeffee;" | 0.99726968 | style="background: #eeffee;" | 1.02595675 | style="background: #fffaee;" | 0.41354 | style="background: #fffaee;" | 0.44401 | style="background: #ffe6ea;" | 0.71833 | style="background: #ffe6ea;" | 0.67125 |
| style="background: #fffdd0;" | Orbital period{{ref label|G|g|none}}
| style="background: #fffdd0;" | days | style="background: #eeffee;" | 87.969 | style="background: #eeffee;" | 224.701 | style="background: #eeffee;" | 365.256363 | style="background: #eeffee;" | 686.971 | style="background: #fffaee;" | 4,332.59 | style="background: #fffaee;" | 10,759.22 | style="background: #ffe6ea;" | 30,688.5 | style="background: #ffe6ea;" | 60,182 |
| style="background: #fffdd0;" | Mean orbital speed
| style="background: #fffdd0;" | km/s | style="background: #eeffee;" | 47.8725 | style="background: #eeffee;" | 35.0214 | style="background: #eeffee;" | 29.7859 | style="background: #eeffee;" | 24.1309 | style="background: #fffaee;" | 13.0697 | style="background: #fffaee;" | 9.6724 | style="background: #ffe6ea;" | 6.8352 | style="background: #ffe6ea;" | 5.4778 |
| colspan="2" style="background: #fffdd0;" | Eccentricity
| style="background: #eeffee;" | 0.20563069 | style="background: #eeffee;" | 0.00677323 | style="background: #eeffee;" | 0.01671022 | style="background: #eeffee;" | 0.09341233 | style="background: #fffaee;" | 0.04839266 | style="background: #fffaee;" | 0.05415060 | style="background: #ffe6ea;" | 0.04716771 | style="background: #ffe6ea;" | 0.00858587 |
| style="background: #fffdd0;" | Inclination{{ref label|F|f|none}}
| style="background: #fffdd0;" | deg. | style="background: #eeffee;" | 7.00 | style="background: #eeffee;" | 3.39 | style="background: #eeffee;" | 0 | style="background: #eeffee;" | 1.85 | style="background: #fffaee;" | 1.31 | style="background: #fffaee;" | 2.48 | style="background: #ffe6ea;" | 0.76 | style="background: #ffe6ea;" | 1.77 |
| style="background: #fffdd0;" | Axial tilt{{ref label|I|i|none}}
| style="background: #fffdd0;" | deg. | style="background: #eeffee;" | 0.0 | style="background: #eeffee;" | 177.3{{ref label|H|h|none}} | style="background: #eeffee;" | 23.44 | style="background: #eeffee;" | 25.19 | style="background: #fffaee;" | 3.12 | style="background: #fffaee;" | 26.73 | style="background: #ffe6ea;" | 97.86{{ref label|H|h|none}} | style="background: #ffe6ea;" | 28.32 |
| style="background: #fffdd0;" | Mean surface temperature
| style="background: #fffdd0;" | K | style="background: #eeffee;" | 440–100 | style="background: #eeffee;" | 730 | style="background: #eeffee;" | 287 | style="background: #eeffee;" | 227 | style="background: #fffaee;" | 152 {{ref label|J|j|none}} | style="background: #fffaee;" | 134 {{ref label|J|j|none}} | style="background: #ffe6ea;" | 76 {{ref label|J|j|none}} | style="background: #ffe6ea;" | 73 {{ref label|J|j|none}} |
| style="background: #fffdd0;" | Mean air temperature{{ref label|K|k|none}}
| style="background: #fffdd0;" | K | style="background: #eeffee;" | | style="background: #eeffee;" | | style="background: #eeffee;" | 288 | style="background: #eeffee;" | | style="background: #fffaee;" | 165 | style="background: #fffaee;" | 135 | style="background: #ffe6ea;" | 76 | style="background: #ffe6ea;" | 73 |
| colspan="2" style="background: #fffdd0;" | Atmospheric composition
| style="background: #eeffee;" | He, Na+ | style="background: #eeffee;" | CO2, N2, SO2 | style="background: #eeffee;" | N2, O2, Ar, CO2 | style="background: #eeffee;" | CO2, N2 | style="background: #fffaee;" | H2, He | style="background: #fffaee;" | H2, He | style="background: #ffe6ea;" | H2, He | style="background: #ffe6ea;" | H2, He |
| colspan="2" style="background: #fffdd0;" | Number of known moons{{ref label|V|v|none}}
| style="background: #eeffee;" | 0 | style="background: #eeffee;" | 0 | style="background: #eeffee;" | 1 | style="background: #eeffee;" | 2 | style="background: #fffaee;" | 97 | style="background: #fffaee;" | 274 | style="background: #ffe6ea;" | 28 | style="background: #ffe6ea;" | 16 |
| colspan="2" style="background: #fffdd0;" | Rings?
| style="background: #eeffee;" | No | style="background: #eeffee;" | No | style="background: #eeffee;" | No | style="background: #eeffee;" | No | style="background: #fffaee;" | Yes | style="background: #fffaee;" | Yes | style="background: #ffe6ea;" | Yes | style="background: #ffe6ea;" | Yes |
| colspan="2" style="background: #fffdd0;" | Planetary discriminant{{ref label|L|l|none}}{{ref label|O|o|none}}
| style="background: #eeffee;" | 9.1{{e|4}} | style="background: #eeffee;" | 1.35{{e|6}} | style="background: #eeffee;" | 1.7{{e|6}} | style="background: #eeffee;" | 1.8{{e|5}} | style="background: #fffaee;" | 6.25{{e|5}} | style="background: #fffaee;" | 1.9{{e|5}} | style="background: #ffe6ea;" | 2.9{{e|4}} | style="background: #ffe6ea;" | 2.4{{e|4}} |
Dwarf planets
{{Main|Dwarf planet}}
{{See also|List of possible dwarf planets}}
Dwarf planets are bodies orbiting the Sun that are massive and warm enough to have achieved hydrostatic equilibrium, but have not cleared their neighbourhoods of similar objects. Since 2008, there have been five dwarf planets recognized by the IAU, although only Pluto has actually been confirmed to be in hydrostatic equilibrium
{{cite journal |last1=Nimmo |first1=Francis |display-authors=etal |title=Mean radius and shape of Pluto and Charon from New Horizons images|journal=Icarus |date=2017 |volume=287 |pages=12–29 |doi=10.1016/j.icarus.2016.06.027|bibcode=2017Icar..287...12N |arxiv=1603.00821|s2cid=44935431}} (Ceres is close to equilibrium, though some anomalies remain unexplained).{{cite book|chapter-url=https://meetingorganizer.copernicus.org/EPSC2018/EPSC2018-645-1.pdf|display-authors=4|author1=Raymond, C.|author2=Castillo-Rogez, J.C.|author3=Park, R.S.|author4=Ermakov, A.|author5=Bland, M.T.|author6=Marchi, S.|author7=Prettyman, T.|author8=Ammannito, E.|author9=De Sanctis, M.C.|author10=Russell, C.T.|date=September 2018|chapter=Dawn Data Reveal Ceres' Complex Crustal Evolution|title=European Planetary Science Congress|volume=12|access-date=30 October 2021|archive-date=30 January 2020|archive-url=https://web.archive.org/web/20200130111631/https://meetingorganizer.copernicus.org/EPSC2018/EPSC2018-645-1.pdf|url-status=live}} Ceres orbits in the asteroid belt, between Mars and Jupiter. The others all orbit beyond Neptune.
| class="wikitable" border="1"
|+Key | bgcolor="#F2E0CE" style="text-align: left" |† Asteroid belt |
| bgcolor="#eeffff" style="text-align: left" |‡ Kuiper belt |
| bgcolor="#CEE0F2" style="text-align: left" |§ Scattered disc |
| bgcolor="#E0CEF2" style="text-align: left" |× Sednoid |
| class="wikitable" style="text-align: center;" |
| colspan="2" rowspan=2 |
! style="background: #F2E0CE;" | †{{dwarfplanet|Ceres}}{{cite web |title=NASA Asteroid Factsheet |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/asteroidfact.html |access-date=2008-11-17 |publisher=NASA |archive-url=https://web.archive.org/web/20100116142816/http://nssdc.gsfc.nasa.gov/planetary/factsheet/asteroidfact.html |archive-date=2010-01-16}} ! style="background: #eff;" | ‡{{dwarfplanet|Pluto}}{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/plutofact.html |title=NASA Pluto factsheet |publisher=NASA |access-date=2008-11-17 |archive-date=19 November 2015 |archive-url=https://archive.today/20151119095810/http://nssdc.gsfc.nasa.gov/planetary/factsheet/plutofact.html |url-status=live }}{{cite web |url=http://solarsystem.nasa.gov/planets/profile.cfm?Object=Pluto&Display=Facts |archive-url=https://web.archive.org/web/20040224190840/http://solarsystem.nasa.gov/planets/profile.cfm?Object=Pluto&Display=Facts |archive-date=2004-02-24 |title=NASA Solar System Exploration Pluto Factsheet |publisher=NASA |access-date=2008-11-17}} ! style="background: #eff;" | ‡{{dwarfplanet|Haumea}}{{cite journal |first1=Alexandra C. |last1=Lockwood |first2=Michael E. |last2=Brown |author-link2=Michael E. Brown |first3=John A. |last3=Stansberry |date=2014 |title=The Size and Shape of the Oblong Dwarf Planet Haumea |journal=Earth, Moon, and Planets |arxiv=1402.4456 |doi=10.1007/s11038-014-9430-1 |volume=111 |issue=3–4 |pages=127–137 |bibcode=2014EM&P..111..127L |s2cid=18646829 }}{{cite journal |first1=David L. |last1=Rabinowitz |author-link1=David L. Rabinowitz |first2=Kristina M. |last2=Barkume |first3=Michael E. |last3=Brown |first4=Henry G. |last4=Roe |first5=Michael |last5=Schwartz |first6=Suzanne W. |last6=Tourtellotte |first7=Chadwick A. |last7=Trujillo |date=2006 |title=Photometric Observations Constraining the Size, Shape, and Albedo of 2003 EL61, a rapidly rotating, Pluto-sized object in the Kuiper Belt |journal=The Astrophysical Journal |volume=639 |issue=2 |pages=1238–1251 |doi=10.1086/499575 |bibcode=2006ApJ...639.1238R |arxiv=astro-ph/0509401|s2cid=11484750 }}{{cite web |title=Jet Propulsion Laboratory Small-Body Database Browser: 136108 Haumea |publisher=NASA's Jet Propulsion Laboratory |quote=2008-05-10 last obs. |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=136108 |access-date=2008-11-13 |archive-date=27 December 2015 |archive-url=https://web.archive.org/web/20151227152421/http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=136108 |url-status=live }} ! style="background: #eff;" | ‡{{dwarfplanet|Makemake}}{{cite web |first=Marc W. |last=Buie |author-link=Marc W. Buie |date=2008-04-05 |title=Orbit fit and astrometric record for 136472 |publisher=SwRI |department=Space Science Department |url=http://www.boulder.swri.edu/~buie/kbo/astrom/136472.html |access-date=2008-07-13 |archive-date=27 May 2020 |archive-url=https://web.archive.org/web/20200527191044/https://www.boulder.swri.edu/~buie/kbo/astrom/136472.html |url-status=live }}{{cite web |title=NASA Small Bodies Database Browser: 136472 Makemake (2005 FY9) |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=136472 |publisher=NASA JPL |access-date=2008-10-03 |archive-date=17 May 2020 |archive-url=https://web.archive.org/web/20200517081526/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=136472 |url-status=live }} (unless otherwise cited) ! style="background: #CEE0F2;" | §{{dwarfplanet|Eris}}{{cite web |title=NASA Small Body Database Browser: Eris |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Eris |publisher=NASA JPL |access-date=2008-11-13 |archive-date=9 January 2019 |archive-url=https://web.archive.org/web/20190109202709/https://ssd.jpl.nasa.gov/?horizons |url-status=live }} (unless otherwise cited) |
|---|
| style="background: black;" | x70px
| style="background: black;" |70x70px | style="background: #181818;" | x70px | style="background: black;" | x70px | style="background: #420001;" | x70px |
| colspan="2" style="background: #fffdd0;" | Symbol{{ref label|Q|q|none}}
| style="background: #F2E0CE;" | x20px | style="background: #eff;" | x20px or x20px | style="background: #eff;" | x20px | style="background: #eff;" | x20px | style="background: #CEE0F2;" | x20px |
| colspan="2" style="background: #fffdd0;" | Symbol (Unicode){{ref label|Q|q|none}}
| style="background: #F2E0CE;" | ⚳ | style="background: #eff;" | ♇ or ⯓ | style="background: #eff;" | 🝻 | style="background: #eff;" | 🝼 | style="background: #CEE0F2;" | ⯰ |
| colspan="2" style="background: #fffdd0;" | Minor planet number
| style="background: #F2E0CE;" | 1 | style="background: #eff;" | 134340 | style="background: #eff;" | 136108 | style="background: #eff;" | 136472 | style="background: #CEE0F2;" | 136199 |
| colspan="2" style="background: #fffdd0;" | Discovery year
| style="background: #F2E0CE;" | 1801 | style="background: #eff;" | 1930 | style="background: #eff;" | 2004 | style="background: #eff;" | 2005 | style="background: #CEE0F2;" | 2005 |
| style="background: #fffdd0;" | Mean distance from the Sun | style="background: #fffdd0;" | km | style="background: #F2E0CE;" | 413,700,000 | style="background: #eff;" | 5,906,380,000 | style="background: #eff;" | 6,484,000,000 | style="background: #eff;" | 6,850,000,000 | style="background: #CEE0F2;" | 10,210,000,000 |
| style="background: #fffdd0;" | Mean radius
| style="background: #fffdd0;" | km | style="background: #F2E0CE;" | 473 | style="background: #eff;" | 1,188.3 | style="background: #eff;" | 816 | style="background: #eff;" | 715 |
| style="background: #fffdd0;" | Volume
| style="background: #fffdd0;" | km3 | style="background: #F2E0CE;" | 4.21{{e|8}} | style="background: #eff;" | 6.99{{e|9}} | style="background: #eff;" | 1.98{{e|9}} | style="background: #eff;" | 1.7{{e|9}} | style="background: #CEE0F2;" | 6.59{{e|9}} |
| style="background: #fffdd0;" | Surface area
| style="background: #fffdd0;" | km2 | style="background: #F2E0CE;" | 2,770,000 | style="background: #eff;" | 17,700,000 | style="background: #eff;" | 8,140,000 | style="background: #eff;" | 6,900,000 | style="background: #CEE0F2;" | 17,000,000 |
| style="background: #fffdd0;" | Mass
| style="background: #fffdd0;" | kg | style="background: #F2E0CE;" | 9.39{{e|20}} | style="background: #eff;" | 1.30{{e|22}} | style="background: #eff;" | ≈ 3.1{{e|21}} | style="background: #CEE0F2;" | 1.65{{e|22}} |
| style="background: #fffdd0;" | Gravitational parameter
| style="background: #fffdd0;" | m3/s2 | style="background: #F2E0CE;" | 6.263 × 1010 | style="background: #eff;" | 8.710 × 1011 | style="background: #eff;" | 2.674 × 1011 | style="background: #eff;" | 2.069 × 1011 | style="background: #CEE0F2;" | 1.108 × 1012 |
| style="background: #fffdd0;" | Density
| style="background: #fffdd0;" | g/cm3 | style="background: #F2E0CE;" | 2.16 | style="background: #eff;" | 1.87 | style="background: #eff;" | 2.02 | style="background: #eff;" | 2.03 | style="background: #CEE0F2;" | 2.43 |
| style="background: #fffdd0;" | Equatorial gravity
| style="background: #fffdd0;" | m/s2 | style="background: #F2E0CE;" | 0.27{{ref label|D|d|none}} | style="background: #eff;" | 0.62 | style="background: #eff;" | 0.63{{ref label|D|d|none}} | style="background: #eff;" | 0.40 | style="background: #CEE0F2;" | 0.82{{ref label|D|d|none}} |
| style="background: #fffdd0;" | Escape velocity
| style="background: #fffdd0;" | km/s{{ref label|E|e|none}} | style="background: #F2E0CE;" | 0.51 | style="background: #eff;" | 1.21 | style="background: #eff;" | 0.91 | style="background: #eff;" | 0.54 | style="background: #CEE0F2;" | 1.37 |
| style="background: #fffdd0;" | Rotation period{{ref label|G|g|none}}
| style="background: #fffdd0;" | days | style="background: #F2E0CE;" | 0.3781 | style="background: #eff;" | 6.3872 | style="background: #eff;" | 0.1631 | style="background: #eff;" | 0.9511 | style="background: #CEE0F2;" | 15.7859 |
| style="background: #fffdd0;" | Orbital period{{ref label|G|g|none}}
| style="background: #fffdd0;" | years | style="background: #F2E0CE;" | 4.599 | style="background: #eff;" | 247.9 | style="background: #eff;" | 283.8 | style="background: #eff;" | 306.2 | style="background: #CEE0F2;" | 559 |
| style="background: #fffdd0;" | Mean orbital speed
| style="background: #fffdd0;" | km/s | style="background: #F2E0CE;" | 17.882 | style="background: #eff;" | 4.75 | style="background: #eff;" | 4.48{{ref label|O|o|none}} | style="background: #eff;" | 4.40{{ref label|O|o|none}} | style="background: #CEE0F2;" | 3.44{{ref label|N|n|none}} |
| colspan="2" style="background: #fffdd0;" | Eccentricity
| style="background: #F2E0CE;" | 0.080 | style="background: #eff;" | 0.249 | style="background: #eff;" | 0.195 | style="background: #eff;" | 0.161 | style="background: #CEE0F2;" | 0.436 |
| style="background: #fffdd0;" | Inclination{{ref label|F|f|none}}
| style="background: #fffdd0;" | deg. | style="background: #F2E0CE;" | 10.59 | style="background: #eff;" | 17.14 | style="background: #eff;" | 28.21 | style="background: #eff;" | 28.98 | style="background: #CEE0F2;" | 44.04 |
| style="background: #fffdd0;" | Axial tilt{{ref label|I|i|none}}
| style="background: #fffdd0;" | deg. | style="background: #F2E0CE;" | 4 | style="background: #eff;" | 119.6{{ref label|H|h|none}} | style="background: #eff;" | ≈ 126{{ref label|H|h|none}} | style="background: #eff;" | ? | style="background: #CEE0F2;" | ≈ 78 |
| style="background: #fffdd0;" | Mean surface temperature{{ref label|W|w|none}}
| style="background: #fffdd0;" | K | style="background: #F2E0CE;" | 167{{cite journal |first1=Olivier |last1=Saint-Pé |first2=Michel |last2=Combes |first3=François J. |last3=Rigaut |title=Ceres surface properties by high-resolution imaging from Earth |date=1993 |volume=105 |issue=2 |pages=271–281 |journal=Icarus |doi=10.1006/icar.1993.1125 |bibcode=1993Icar..105..271S }} | style="background: #eff;" | 30 | style="background: #CEE0F2;" | 30 |
| colspan="2" style="background: #fffdd0;" | Atmospheric composition
| style="background: #F2E0CE;" | H2O | style="background: #eff;" | N2, CH4, CO | style="background: #eff;" |? |
| colspan="2" style="background: #fffdd0;" | Number of known moons{{ref label|V|v|none}}
| style="background: #F2E0CE;" | 0 | style="background: #eff;" | 5 | style="background: #eff;" | 2{{cite conference |first1=Darin |last1=Ragozzine |first2=Michael E. |last2=Brown |first3=Chadwick A. |last3=Trujillo |first4=Emily L. |last4=Schaller |title=Orbits and Masses of the 2003 EL61 Satellite System |url=http://www.abstractsonline.com/viewer/viewAbstract.asp?CKey={421E1C09-F75A-4ED0-916C-8C0DDB81754D}&MKey={35A8F7D5-A145-4C52-8514-0B0340308E94}&AKey={AAF9AABA-B0FF-4235-8AEC-74F22FC76386}&SKey={545CAD5F-068B-4FFC-A6E2-1F2A0C6ED978} |conference=AAS DPS conference 2008 |access-date=2008-10-17 |archive-url=https://web.archive.org/web/20130718182107/http://www.abstractsonline.com/viewer/viewAbstract.asp?CKey=%7B421E1C09-F75A-4ED0-916C-8C0DDB81754D%7D&MKey=%7B35A8F7D5-A145-4C52-8514-0B0340308E94%7D&AKey=%7BAAF9AABA-B0FF-4235-8AEC-74F22FC76386%7D&SKey=%7B545CAD5F-068B-4FFC-A6E2-1F2A0C6ED978%7D |archive-date=2013-07-18}} | style="background: #eff;" |1{{cite news |last=Chang |first=Kenneth |date=26 April 2016 |title=Makemake, the Moonless Dwarf Planet, Has a Moon, After All |url=https://www.nytimes.com/2016/04/27/science/makemake-the-moonless-dwarf-planet-has-a-moon-after-all.html |newspaper=The New York Times |access-date=26 April 2016 |archive-date=17 August 2019 |archive-url=https://web.archive.org/web/20190817085223/https://www.nytimes.com/2016/04/27/science/makemake-the-moonless-dwarf-planet-has-a-moon-after-all.html |url-status=live }} | style="background: #CEE0F2;" | 1{{cite journal |title=Satellites of the largest Kuiper belt objects |first1=Michael E. |last1=Brown |first2=Marcos A. |last2=van Dam |first3=Antonin H. |last3=Bouchez |first4=David |last4=Le Mignant |first5=Chadwick A. |last5=Trujillo |first6=Randall D. |last6=Campbell |display-authors=6 |first7=Jason C. Y. |last7=Chin |first8=Albert R. |last8=Conrad |first9=Scott |last9=Hartman |first10=Erik M. |last10=Johansson |first11=Robert E. |last11=Lafon |first12=David L. |last12=Rabinowitz |first13=Paul |last13=Stomski |first14=Doug |last14=Summers |first15=Peter L. |last15=Wizinowich |journal=The Astrophysical Journal |date=2006 |volume=639 |issue=1 |pages=L43–L46 |doi=10.1086/501524 |arxiv=astro-ph/0510029 |bibcode=2006ApJ...639L..43B|s2cid=2578831 }} |
| colspan="2" style="background: #fffdd0;" | Rings?
| style="background: #F2E0CE;" | No | style="background: #eff;" | No | style="background: #eff;" | Yes | style="background: #eff;" | ? | style="background: #CEE0F2;" | ? |
| colspan="2" style="background: #fffdd0;" | Planetary discriminant{{ref label|L|l|none}}{{ref label|O|o|none}}
| style="background: #F2E0CE;" | 0.33 | style="background: #eff;" | 0.077 | style="background: #eff;" | 0.023 | style="background: #eff;" | 0.02 | style="background: #CEE0F2;" | 0.10 |
Astronomers usually refer to solid bodies such as Ceres as dwarf planets, even if they are not strictly in hydrostatic equilibrium. They generally agree that several other trans-Neptunian objects (TNOs) may be large enough to be dwarf planets, given current uncertainties. However, there has been disagreement on the required size. Early speculations were based on the small moons of the giant planets, which attain roundness around a threshold of 200 km radius.{{cite web|url=http://web.gps.caltech.edu/~mbrown/dwarfplanets/|author=Mike Brown|title=The Dwarf Planets|access-date=2008-01-20|author-link=Michael E. Brown|archive-date=21 April 2020|archive-url=https://web.archive.org/web/20200421065407/http://web.gps.caltech.edu/~mbrown/dwarfplanets/|url-status=live}} However, these moons are at higher temperatures than TNOs and are icier than TNOs are likely to be. Estimates from an IAU question-and-answer press release from 2006, giving 800 km radius and {{val|0.5|e=21|u=kg}} mass as cut-offs that normally would be enough for hydrostatic equilibrium, while stating that observation would be needed to determine the status of borderline cases.{{cite web |title='Planet Definition' Questions & Answers Sheet |url=https://www.iau.org/static/archives/releases/doc/iau0601_q_answers.doc |publisher=International Astronomical Union |date=August 24, 2006 |access-date=October 16, 2021 |archive-date=7 May 2021 |archive-url=https://web.archive.org/web/20210507125920/https://www.iau.org/static/archives/releases/doc/iau0601_q_answers.doc |url-status=live }} Many TNOs in the 200–500 km radius range are dark and low-density bodies, which suggests that they retain internal porosity from their formation, and hence are not planetary bodies (as planetary bodies have sufficient gravitation to collapse out such porosity).
In 2023, Emery et al. wrote that near-infrared spectroscopy by the James Webb Space Telescope (JWST) in 2022 suggests that Sedna, Gonggong, and Quaoar underwent internal melting, differentiation, and chemical evolution, like the larger dwarf planets Pluto, Eris, Haumea, and Makemake, but unlike "all smaller KBOs". This is because light hydrocarbons are present on their surfaces (e.g. ethane, acetylene, and ethylene), which implies that methane is continuously being resupplied, and that methane would likely come from internal geochemistry. On the other hand, the surfaces of Sedna, Gonggong, and Quaoar have low abundances of CO and CO2, similar to Pluto, Eris, and Makemake, but in contrast to smaller bodies. This suggests that the threshold for dwarf planethood in the trans-Neptunian region is around 500 km radius.{{cite journal|last1=Emery|first1=J. P. |first2=I. |last2=Wong |first3=R. |last3=Brunetto |first4=J. C. |last4=Cook |first5=N. |last5=Pinilla-Alonso |first6=J. A. |last6=Stansberry |first7=B. J. |last7=Holler |first8=W. M. |last8=Grundy |first9=S. |last9=Protopapa |first10=A. C. |last10=Souza-Feliciano |first11=E. |last11=Fernández-Valenzuela |first12=J. I. |last12=Lunine |first13=D. C. |last13=Hines |author-link=|date=2024|title=A Tale of 3 Dwarf Planets: Ices and Organics on Sedna, Gonggong, and Quaoar from JWST Spectroscopy|journal=Icarus |volume=414 |doi=10.1016/j.icarus.2024.116017 |arxiv=2309.15230|bibcode=2024Icar..41416017E }}
In 2024, Kiss et al. found that Quaoar has an ellipsoidal shape incompatible with hydrostatic equilibrium for its current spin. They hypothesised that Quaoar originally had a rapid rotation and was in hydrostatic equilibrium, but that its shape became "frozen in" and did not change as it spun down due to tidal forces from its moon Weywot.{{cite journal
|display-authors = etal
|first1 = C. |last1 = Kiss
|first2 = T. G. |last2 = Müller
|first3 = G. |last3 = Marton
|first4 = R. |last4 = Szakáts
|first5 = A. |last5 = Pál
|first6 = L. |last6 = Molnár
|title = The visible and thermal light curve of the large Kuiper belt object (50000) Quaoar
|journal = Astronomy & Astrophysics
|date = March 2024
|volume = 684
|issue =
|pages = A50 |doi = 10.1051/0004-6361/202348054
|arxiv = 2401.12679
|bibcode = 2024A&A...684A..50K}} If so, this would resemble the situation of Saturn's moon Iapetus, which is too oblate for its current spin.Cowen, R. (2007). Idiosyncratic Iapetus, Science News vol. 172, pp. 104–106. [http://www.sciencenews.org/articles/20070818/bob8ref.asp references] {{Webarchive|url=https://web.archive.org/web/20071013165655/http://www.sciencenews.org/articles/20070818/bob8ref.asp |date=2007-10-13 }}{{cite journal| doi = 10.1016/j.icarus.2010.01.025| last1 = Thomas| first1 = P. C.| date = July 2010| title = Sizes, shapes, and derived properties of the saturnian satellites after the Cassini nominal mission| journal = Icarus| volume = 208| issue = 1| pages = 395–401| url = http://www.ciclops.org/media/sp/2011/6794_16344_0.pdf| bibcode = 2010Icar..208..395T| access-date = 2015-09-25| archive-date = 2018-12-23| archive-url = https://web.archive.org/web/20181223003125/http://www.ciclops.org/media/sp/2011/6794_16344_0.pdf| url-status = dead}} Iapetus is generally still considered a planetary-mass moon nonetheless, though not always.{{cite journal |last1=Chen |first1=Jingjing |last2=Kipping |first2=David |date=2016 |title=Probabilistic Forecasting of the Masses and Radii of Other Worlds |journal=The Astrophysical Journal |volume=834 |issue=1 |page=17 |doi= 10.3847/1538-4357/834/1/17|arxiv=1603.08614 |s2cid=119114880 |doi-access=free |bibcode=2017ApJ...834...17C }}
The table below gives Orcus, Quaoar, Gonggong, and Sedna as additional consensus dwarf planets; slightly smaller Salacia, which is larger than 400 km radius, has been included as a borderline case for comparison, (and is therefore italicized).
| class="wikitable" style="text-align: center;" |
| colspan="2" rowspan=2 |
! style="background: #eff;" | ‡Orcus{{cite web |type=2020-01-04 last obs |title=JPL Small-Body Database Browser: 90482 Orcus (2004 DW) |publisher=Jet Propulsion Laboratory |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2090482 |access-date=2020-02-20 |archive-date=8 July 2019 |archive-url=https://web.archive.org/web/20190708202911/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2090482 |url-status=live }} ! style="background: #eff;" | ‡Salacia{{cite web |type=2019-09-21 last obs |title=JPL Small-Body Database Browser: 120347 Salacia (2004 SB60) |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2120347 |publisher=Jet Propulsion Laboratory |access-date=2020-02-20 |archive-date=3 April 2017 |archive-url=https://web.archive.org/web/20170403194747/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2120347 |url-status=live }} ! style="background: #eff;" | ‡Quaoar{{cite web |type=2019-08-31 last obs |title=NASA JPL Database Browser: 50000 Quaoar |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2050000 |publisher=Jet Propulsion Laboratory |access-date=2020-02-20 |archive-date=2 October 2018 |archive-url=https://web.archive.org/web/20181002121446/http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2050000 |url-status=live }} ! style="background: #CEE0F2;" | §Gonggong{{cite web |title=NASA Small Bodies Database Browser: 225088 Gonggong (2007 OR10) |publisher=Jet Propulsion Laboratory |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2225088 |access-date=2020-02-20 |archive-date=1 March 2017 |archive-url=https://web.archive.org/web/20170301010854/http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2225088 |url-status=live }} ! style="background: #E0CEF2;" | ×Sedna{{cite web |first=Marc W. |last=Buie |date=2007-08-13 |title=Orbit Fit and Astrometric record for 90377 |publisher=Deep Ecliptic Survey |url=http://www.boulder.swri.edu/~buie/kbo/astrom/90377.html |access-date=2006-01-17 |archive-date=20 May 2011 |archive-url=https://web.archive.org/web/20110520122821/http://www.boulder.swri.edu/~buie/kbo/astrom/90377.html |url-status=live }} |
|---|
| style="background: #181818;" | x55px
| style="background: #181818;" | x55px | style="background: #181818;" | x55px | style="background: #3c3c3c;" | x55px | style="background: #181818;" | x55px |
| colspan="2" style="background: #fffdd0;" | Symbol{{ref label|Q|q|none}}
| style="background: #eff;" | x20px | style="background: #eff;" | | style="background: #eff;" | x20px | style="background: #CEE0F2;" | x20px | style="background: #E0CEF2;" | x20px |
| colspan="2" style="background: #fffdd0;" | Symbol (Unicode){{ref label|Q|q|none}}
| style="background: #eff;" | 🝿 | style="background: #eff;" | | style="background: #eff;" | 🝾 | style="background: #CEE0F2;" | 🝽 | style="background: #E0CEF2;" | ⯲ |
| colspan="2" style="background: #fffdd0;" | Minor-planet number
| style="background: #eff;" | 90482 | style="background: #eff;" | 120347 | style="background: #eff;" | 50000 | style="background: #CEE0F2;" | 225088 | style="background: #E0CEF2;" | 90377 |
| colspan="2" style="background: #fffdd0;" | Discovery year
| style="background: #eff;" | 2004 | style="background: #eff;" | 2004 | style="background: #eff;" | 2002 | style="background: #CEE0F2;" | 2007 | style="background: #E0CEF2;" | 2003 |
| style="background: #fffdd0;" | Semi-major axis
| style="background: #fffdd0;" | km | style="background: #eff;" | 5,896,946,000 | style="background: #eff;" | 6,310,600,000 | style="background: #eff;" | 6,535,930,000 | style="background: #CEE0F2;" | 10,072,433,340 | style="background: #E0CEF2;" | 78,668,000,000 |
| style="background: #fffdd0;" | Mean radius{{ref label|S|s|none}}
| style="background: #fffdd0;" | km | style="background: #eff;" | 423{{cite journal |title=Mutual Orbit Orientations of Transneptunian Binaries |url=http://www2.lowell.edu/users/grundy/abstracts/preprints/2019.TNB_orbits.pdf |first1=W. M. |last1=Grundy |first2=K. S. |last2=Noll |first3=H. G. |last3=Roe |first4=M. W. |last4=Buie |first5=S. B. |last5=Porter |first6=A. H. |last6=Parker |first7=D. |last7=Nesvorný |first8=S. D. |last8=Benecchi |first9=D. C. |last9=Stephens |first10=C. A. |last10=Trujillo |journal=Icarus |volume=334 |pages=62–78 |year=2019 |doi=10.1016/j.icarus.2019.03.035 |bibcode=2019Icar..334...62G |s2cid=133585837 |issn=0019-1035 |access-date=2019-10-26 |archive-url=https://web.archive.org/web/20200115091416/http://www2.lowell.edu/~grundy/abstracts/preprints/2019.TNB_orbits.pdf |archive-date=2020-01-15 }} |
| style="background: #fffdd0;" | Surface area{{ref label|A|a|none}}
| style="background: #fffdd0;" | km2 | style="background: #eff;" | 2,641,700 | style="background: #eff;" | 2,248,500 | style="background: #eff;" | 3,870,800 | style="background: #CEE0F2;" | 4,932,300 | style="background: #E0CEF2;" | 3,110,200 |
| style="background: #fffdd0;" | Volume{{ref label|B|b|none}}
| style="background: #fffdd0;" | km3 | style="background: #eff;" | 403,744,500 | style="background: #eff;" | 317,036,800 | style="background: #eff;" | 716,089,900 | style="background: #CEE0F2;" | 1,030,034,600 | style="background: #E0CEF2;" | 515,784,000 |
| style="background: #fffdd0;" | Mass{{ref label|T|t|none}}
| style="background: #fffdd0;" | kg | style="background: #eff;" | 5.48{{e|20}}{{cite journal |arxiv = 2307.04848 | last1=Brown | first1=Michael E. | last2=Butler | first2=Bryan J. | title=Masses and densities of dwarf planet satellites measured with ALMA | journal=The Planetary Science Journal | date=2023 | volume=4 | issue=10 | page=193 | doi=10.3847/PSJ/ace52a | doi-access=free | bibcode=2023PSJ.....4..193B }} | style="background: #eff;" | 4.9{{e|20}} | style="background: #eff;" | 1.20{{e|21}} | style="background: #CEE0F2;" | 1.75{{e|21}} | style="background: #E0CEF2;" | ? |
| style="background: #fffdd0;" | Density{{ref label|T|t|none}}
| style="background: #fffdd0;" | g/cm3 | style="background: #eff;" | {{val|1.4|0.2}} | style="background: #eff;" | {{val|1.50|0.12}} | style="background: #eff;" | ≈ {{val|1.7}} | style="background: #CEE0F2;" | {{val|1.74|0.16}} | style="background: #E0CEF2;" | ? |
| style="background: #fffdd0;" | Equatorial gravity{{ref label|D|d|none}}
| style="background: #fffdd0;" | m/s2 | style="background: #eff;" | {{Gr|0.632|497.5|2}} | style="background: #eff;" | {{Gr|0.49|432|2}} | style="background: #eff;" | {{Gr|1.20|569|2}} | style="background: #CEE0F2;" | {{Gr|1.75|615|2}} | style="background: #E0CEF2;" | ? |
| style="background: #fffdd0;" | Escape velocity{{ref label|E|e|none}}
| style="background: #fffdd0;" | km/s | style="background: #eff;" | {{V2|0.632|497.5|2}} | style="background: #eff;" | {{V2|0.49|432|2}} | style="background: #eff;" | {{V2|1.20|569|2}} | style="background: #CEE0F2;" | {{V2|1.75|615|2}} | style="background: #E0CEF2;" | ? |
| style="background: #fffdd0;" | Rotation period{{ref label|G|g|none}}
| style="background: #fffdd0;" | days | style="background: #eff;" | 9.54? | style="background: #eff;" | ? | style="background: #eff;" | 0.7367{{Cite Q|Q116754015|display-authors=1}} | style="background: #CEE0F2;" | 0.9333 | style="background: #E0CEF2;" | 0.4280{{cite web |type=2016-01-12 last obs |title=JPL Small-Body Database Browser: 90377 Sedna (2003 VB12) |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2090377 |access-date=28 May 2019 |archive-date=12 April 2019 |archive-url=https://web.archive.org/web/20190412221701/http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2090377 |url-status=live }} |
| style="background: #fffdd0;" | Orbital period{{ref label|G|g|none}}
| style="background: #fffdd0;" | years | style="background: #eff;" | 247.49 | style="background: #eff;" | 273.98 | style="background: #eff;" | 287.97 | style="background: #CEE0F2;" | 552.52 | style="background: #E0CEF2;" | 12,059 |
| style="background: #fffdd0;" | Mean orbital speed
| style="background: #fffdd0;" | km/s | style="background: #eff;" | 4.68 | style="background: #eff;" | 4.57 | style="background: #eff;" | 4.52 | style="background: #CEE0F2;" | 3.63 | style="background: #E0CEF2;" | 1.04 |
| colspan="2" style="background: #fffdd0;" | Eccentricity
| style="background: #eff;" | 0.226 | style="background: #eff;" | 0.106 | style="background: #eff;" | 0.038 | style="background: #CEE0F2;" | 0.506 | style="background: #E0CEF2;" | 0.855 |
| style="background: #fffdd0;" | Inclination{{ref label|F|f|none}}
| style="background: #fffdd0;" | deg. | style="background: #eff;" | 20.59 | style="background: #eff;" | 23.92 | style="background: #eff;" | 7.99 | style="background: #CEE0F2;" | 30.74 | style="background: #E0CEF2;" | 11.93 |
| style="background: #fffdd0;" | Axial tilt{{ref label|I|i|none}}
| style="background: #fffdd0;" | deg. | style="background: #eff;" | ? | style="background: #eff;" | ? | style="background: #eff;" | 13.6 or 14.0{{Cite Q|Q117802048|display-authors=1}} | style="background: #CEE0F2;" | ? | style="background: #E0CEF2;" | ? |
| style="background: #fffdd0;" | Mean surface temperature{{ref label|W|w|none}}
| style="background: #fffdd0;" | K | style="background: #eff;" | ≈ 42 | style="background: #eff;" | ≈ 43 | style="background: #eff;" | ≈ 41 | style="background: #CEE0F2;" | ≈ 30 | style="background: #E0CEF2;" | ≈ 12 |
| colspan="2" style="background: #fffdd0;" | Number of known moons
| style="background: #eff;" | 1{{cite web |url=http://www.boulder.swri.edu/ekonews/issues/past/n051/html/index.html |title=Distant EKO |website=The Kuiper Belt Electronic newsletter |date=March 2007 |access-date=2008-11-17 |archive-date=12 September 2007 |archive-url=https://web.archive.org/web/20070912203658/http://www.boulder.swri.edu/ekonews/issues/past/n051/html/index.html |url-status=live }} | style="background: #eff;" | 1 | style="background: #eff;" | 1{{cite web |title=IAUC 8812: Sats of 2003 AZ_84, (50000), (55637), (90482); V1281 Sco; V1280 Sco |url=http://www.cbat.eps.harvard.edu/iauc/08800/08812.html |publisher=International Astronomical Union |access-date=2011-07-05 |archive-date=19 July 2011 |archive-url=https://web.archive.org/web/20110719205520/http://cbat.eps.harvard.edu/iauc/08800/08812.html |url-status=live }} | style="background: #CEE0F2;" | 1 | style="background: #E0CEF2;" | 0 |
| colspan="2" style="background: #fffdd0;" | Rings?
| style="background: #eff;" | ? | style="background: #eff;" | ? | style="background: #eff;" | Yes | style="background: #CEE0F2;" | ? | style="background: #E0CEF2;" | ? |
| colspan="2" style="background: #fffdd0;" | Planetary discriminant{{ref label|L|l|none}}{{ref label|O|o|none}}
| style="background: #eff;" | 0.003 | style="background: #eff;" | <0.1 | style="background: #eff;" | 0.0015 | style="background: #CEE0F2;" | <0.1 | style="background: #E0CEF2;" | ?{{ref label|X|x|none}} |
| colspan="2" style="background: #fffdd0;" | Absolute magnitude (H)
| style="background: #eff;" | 2.3 | style="background: #eff;" | 4.1 | style="background: #eff;" | 2.71 | style="background: #CEE0F2;" | 1.8 | style="background: #E0CEF2;" | 1.5 |
As for objects in the asteroid belt, none are generally agreed as dwarf planets today among astronomers other than Ceres. The second- through fifth-largest asteroids have been discussed as candidates. Vesta (radius {{val|262.7|0.1|u=km}}), the second-largest asteroid, appears to have a differentiated interior and therefore likely was once a dwarf planet, but it is no longer very round today.{{cite press release
|author1=Savage, Don
|author2=Jones, Tammy
|author3=Villard, Ray
|date=1995-04-19
|title=Asteroid or mini-planet? Hubble maps the ancient surface of Vesta
|id=News Release STScI-1995-20
|website=HubbleSite
|url=http://hubblesite.org/newscenter/archive/releases/1995/20/image/c
|access-date=2006-10-17
|archive-date=13 August 2012
|archive-url=https://web.archive.org/web/20120813040524/http://hubblesite.org/newscenter/archive/releases/1995/20/image/c/
|url-status=live
}} Pallas (radius {{val|255.5|2|u=km}}), the third-largest asteroid, appears never to have completed differentiation and likewise has an irregular shape. Vesta and Pallas are nonetheless sometimes considered small terrestrial planets anyway by sources preferring a geophysical definition, because they do share similarities to the rocky planets of the inner solar system.{{Cite web |editor=Emily Lakdawalla |date=21 April 2020 |title=What Is A Planet? |url=https://www.planetary.org/worlds/what-is-a-planet |access-date=2023-01-01 |website=The Planetary Society |language=en-US |archive-url=https://web.archive.org/web/20220122142140/https://www.planetary.org/worlds/what-is-a-planet |archive-date=2022-01-22}} The fourth-largest asteroid, Hygiea (radius {{val|216.5|4|u=km}}), is icy. The question remains open if it is currently in hydrostatic equilibrium: while Hygiea is round today, it was probably previously catastrophically disrupted and today might be just a gravitational aggregate of the pieces.{{cite journal
|title=A basin-free spherical shape as an outcome of a giant impact on asteroid Hygiea
|url=https://www.eso.org/public/archives/releases/sciencepapers/eso1918/eso1918a.pdf
|display-authors=etal
|last1=Vernazza
|first1=P.
|last2=Jorda
|first2=L.
|last3=Ševeček
|first3=P.
|last4=Brož
|first4=M.
|last5=Viikinkoski
|first5=M.
|last6=Hanuš
|first6=J.
|journal=Nature Astronomy
|volume=273
|issue=2
|pages=136–141
|doi=10.1038/s41550-019-0915-8
|hdl=10045/103308
|access-date=2019-10-28
|year=2020
|bibcode=2020NatAs...4..136V
|s2cid=209938346
|hdl-access=free
|archive-date=11 November 2020
|archive-url=https://web.archive.org/web/20201111195300/https://www.eso.org/public/archives/releases/sciencepapers/eso1918/eso1918a.pdf
|url-status=live
}} The fifth-largest asteroid, Interamnia (radius {{val|166|3|u=km}}), is icy and has a shape consistent with hydrostatic equilibrium for a slightly shorter rotation period than it now has.{{cite journal|arxiv=1911.13049|doi=10.1051/0004-6361/201936639|title=(704) Interamnia: A transitional object between a dwarf planet and a typical irregular-shaped minor body|year=2020|last1=Hanuš|first1=J.|last2=Vernazza|first2=P.|last3=Viikinkoski|first3=M.|last4=Ferrais|first4=M.|last5=Rambaux|first5=N.|last6=Podlewska-Gaca|first6=E.|last7=Drouard|first7=A.|last8=Jorda|first8=L.|last9=Jehin|first9=E.|last10=Carry|first10=B.|last11=Marsset|first11=M.|last12=Marchis|first12=F.|last13=Warner|first13=B.|last14=Behrend|first14=R.|last15=Asenjo|first15=V.|last16=Berger|first16=N.|last17=Bronikowska|first17=M.|last18=Brothers|first18=T.|last19=Charbonnel|first19=S.|last20=Colazo|first20=C.|last21=Coliac|first21=J.-F.|last22=Duffard|first22=R.|last23=Jones|first23=A.|last24=Leroy|first24=A.|last25=Marciniak|first25=A.|last26=Melia|first26=R.|last27=Molina|first27=D.|last28=Nadolny|first28=J.|last29=Person|first29=M.|last30=Pejcha|first30=O.|s2cid=208512707|journal=Astronomy & Astrophysics|volume=633|pages=A65|bibcode=2020A&A...633A..65H|display-authors=29}}
Satellites
{{Main|Planetary-mass moon}}
{{Further|List of natural satellites}}
There are at least 19 natural satellites in the Solar System that are known to be massive enough to be close to hydrostatic equilibrium: seven of Saturn, five of Uranus, four of Jupiter, and one each of Earth, Neptune, and Pluto. Alan Stern calls these satellite planets, although the term major moon is more common. The smallest natural satellite that is gravitationally rounded is Saturn I Mimas (radius {{val|198.2|0.4|u=km}}). This is smaller than the largest natural satellite that is known not to be gravitationally rounded, Neptune VIII Proteus (radius {{val|210|7|u=km}}).
Several of these were once in equilibrium but are no longer: these include Earth's moon{{cite journal | title=Interpretation of lunar potential fields | first=Stanley Keith | last=Runcorn | date=March 31, 1977 | journal=Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences | doi=10.1098/rsta.1977.0094 | bibcode=1977RSPTA.285..507R | volume=285 | issue=1327 | pages=507–516 | s2cid=124703189 }} and all of the moons listed for Saturn apart from Titan and Rhea. The status of Callisto, Titan, and Rhea is uncertain, as is that of the moons of Uranus, Pluto and Eris.W.M. Grundy, K.S. Noll, M.W. Buie, S.D. Benecchi, D. Ragozzine & H.G. Roe, 'The Mutual Orbit, Mass, and Density of Transneptunian Binary Gǃkúnǁʼhòmdímà ({{mp|(229762) 2007 UK|126}})', Icarus [http://www2.lowell.edu/~grundy/abstracts/2019.G-G.html (forthcoming, available online 30 March 2019)] {{Webarchive|url=https://web.archive.org/web/20190407045334/http://www2.lowell.edu/~grundy/abstracts/2019.G-G.html |date=7 April 2019 }} DOI: 10.1016/j.icarus.2018.12.037, The other large moons (Io, Europa, Ganymede, and Triton) are generally believed to still be in equilibrium today. Other moons that were once in equilibrium but are no longer very round, such as Saturn IX Phoebe (radius {{val|106.5|0.7|u=km}}), are not included. In addition to not being in equilibrium, Mimas and Tethys have very low densities and it has been suggested that they may have non-negligible internal porosity,{{cite journal |last1=Leliwa-Kopystyński |first1=J. |last2=Kossacki |first2=K. J. |date=2000 |title=Evolution of porosity in small icy bodies |journal=Planetary and Space Science |volume=48 |issue=7–8 |pages=727–745 |doi=10.1016/S0032-0633(00)00038-6 |bibcode=2000P&SS...48..727L }}{{cite journal |url=https://meetingorganizer.copernicus.org/EPSC2022/EPSC2022-732.html |title=Red Streaks on Tethys: Evidence for Recent Activity |last1=Schenk |first1=Paul |last2=Buratti |first2=Bonnie |last3=Clark |first3=Roger |last4=Byrne |first4=Paul |last5=McKinnon |first5=William |last6=Matsuyama |first6=Isamu |last7=Nimmo |first7=Francis |last8=Scipioni |first8=Francesca |date=2022 |journal=European Planetary Science Congress |publisher=Europlanet Science Congress 2022 |doi=10.5194/epsc2022-732 |doi-access=free |bibcode=2022EPSC...16..732S |access-date=20 November 2022 |archive-date=20 November 2022 |archive-url=https://web.archive.org/web/20221120001336/https://meetingorganizer.copernicus.org/EPSC2022/EPSC2022-732.html |url-status=live |url-access=subscription }} in which case they would not be satellite planets.
The moons of the trans-Neptunian objects (other than Charon) have not been included, because they appear to follow the normal situation for TNOs rather than the moons of Saturn and Uranus, and become solid at a larger size (900–1000 km diameter, rather than 400 km as for the moons of Saturn and Uranus). Eris I Dysnomia and Orcus I Vanth, though larger than Mimas, are dark bodies in the size range that should allow for internal porosity, and in the case of Dysnomia a low density is known.
Satellites are listed first in order from the Sun, and second in order from their parent body. For the round moons, this mostly matches the Roman numeral designations, with the exceptions of Iapetus and the Uranian system. This is because the Roman numeral designations originally reflected distance from the parent planet and were updated for each new discovery until 1851, but by 1892, the numbering system for the then-known satellites had become "frozen" and from then on followed order of discovery. Thus Miranda (discovered 1948) is Uranus V despite being the innermost of Uranus' five round satellites. The missing Saturn VII is Hyperion, which is not large enough to be round (mean radius {{val|135|4|u=km}}).
| class="wikitable" border="1"
|+Key | style="background-color: #B0E0E6;" |🜨 Satellite of Earth |
| style="background-color: #FFA6C9;" |♃ Satellite of Jupiter |
| style="background-color: #FBEC5D;" |♄ Satellite of Saturn |
| style="background-color: #7FFFD4;" |⛢ Satellite of Uranus |
| style="background-color: #F0FFFF;" |♆ Satellite of Neptune |
| style="background-color: #CCCCFF;" |♇ Satellite of Pluto |
| class="wikitable" style="text-align: center;" |
| colspan="2" rowspan=2 |
! style="background: #b0e0e6;" | 🜨Moon{{Cite web|publisher=NASA|year=2021|last=Williams|first=David R.|title=Moon Fact Sheet|url=https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html|access-date=2023-01-01|archive-date=2 April 2019|archive-url=https://web.archive.org/web/20190402143754/https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html|url-status=live}} ! style="background: #ffa6c9;" | ♃Io{{cite web|title=NASA Io Factsheet|url=http://www2.jpl.nasa.gov/galileo/io/fact.html#stats|archive-url=https://web.archive.org/web/19990422163254/http://www.jpl.nasa.gov/galileo/io/fact.html#stats|archive-date=1999-04-22|publisher=NASA|access-date=2008-11-16}} (unless otherwise cited) ! style="background: #ffa6c9;" | ♃Europa{{cite web|title=NASA Europa Factsheet|url=http://www2.jpl.nasa.gov/galileo/europa/|archive-url=https://web.archive.org/web/19970105180851/http://www.jpl.nasa.gov/galileo/europa/|archive-date=1997-01-05|publisher=NASA|access-date=2008-11-16}} (unless otherwise cited) ! style="background: #ffa6c9;" | ♃Ganymede{{cite web|title=NASA Ganymede Factsheet|url=http://www2.jpl.nasa.gov/galileo/ganymede/fact.html|archive-url=https://web.archive.org/web/19970105182450/http://www.jpl.nasa.gov/galileo/ganymede/fact.html|archive-date=1997-01-05|publisher=NASA|access-date=2008-11-16}} (unless otherwise cited) ! style="background: #ffa6c9;" | ♃Callisto{{cite web|title=NASA Callisto Factsheet|publisher=NASA|url=http://www2.jpl.nasa.gov/galileo/callisto/|archive-url=https://web.archive.org/web/19970105182324/http://www.jpl.nasa.gov/galileo/callisto/|archive-date=1997-01-05|access-date=2008-11-16}} ! style="background: #fbec5d;" | ♄Mimas{{ref label|P|p|none}} ! style="background: #fbec5d;" | ♄Enceladus{{ref label|P|p|none}} ! style="background: #fbec5d;" | ♄Tethys{{ref label|P|p|none}} ! style="background: #fbec5d;" | ♄Dione{{ref label|P|p|none}} ! style="background: #fbec5d;" | ♄Rhea{{ref label|P|p|none}} |
|---|
| style="background: black;" | x70px
| style="background: black;" |70x70px | style="background: black;" | x70px | style="background: black;" | 70x70px | style="background: black;" | x70px | style="background: black;" | x70px | style="background: black;" | 70x70px | style="background: black;" | x70px | style="background: black;" | x70px | style="background: black;" | x70px |
| colspan="2" style="background: #fffdd0;" | Roman numeral designation
| style="background: #b0e0e6;" | Earth I | style="background: #ffa6c9;" | Jupiter I | style="background: #ffa6c9;" | Jupiter II | style="background: #ffa6c9;" | Jupiter III | style="background: #ffa6c9;" | Jupiter IV | style="background: #fbec5d;" | Saturn I | style="background: #fbec5d;" | Saturn II | style="background: #fbec5d;" | Saturn III | style="background: #fbec5d;" | Saturn IV | style="background: #fbec5d;" | Saturn V |
| colspan="2" style="background: #fffdd0;" | Symbol{{ref label|Q|q|none}}
| style="background: #b0e0e6;" | File:Moon decrescent symbol (fixed width).svg | style="background: #ffa6c9;" | JI | style="background: #ffa6c9;" | JII | style="background: #ffa6c9;" | JIII | style="background: #ffa6c9;" | JIV | style="background: #fbec5d;" | SI | style="background: #fbec5d;" | SII | style="background: #fbec5d;" | SIII | style="background: #fbec5d;" | SIV | style="background: #fbec5d;" | SV |
| colspan="2" style="background: #fffdd0;" | Symbol (Unicode){{ref label|Q|q|none}}
| style="background: #b0e0e6;" | ☾ | style="background: #ffa6c9;" | | style="background: #ffa6c9;" | | style="background: #ffa6c9;" | | style="background: #ffa6c9;" | | style="background: #fbec5d;" | | style="background: #fbec5d;" | | style="background: #fbec5d;" | | style="background: #fbec5d;" | | style="background: #fbec5d;" | |
| colspan="2" style="background: #fffdd0;" | Discovery year
| style="background: #b0e0e6;" | Prehistoric | style="background: #ffa6c9;" | 1610 | style="background: #ffa6c9;" | 1610 | style="background: #ffa6c9;" | 1610 | style="background: #ffa6c9;" | 1610 | style="background: #fbec5d;" | 1789 | style="background: #fbec5d;" | 1789 | style="background: #fbec5d;" | 1684 | style="background: #fbec5d;" | 1684 | style="background: #fbec5d;" | 1672 |
| style="background: #fffdd0;" | Mean distance from primary | style="background: #fffdd0;" | km | style="background: #b0e0e6;" | 384,399 | style="background: #ffa6c9;" | 421,600 | style="background: #ffa6c9;" | 670,900 | style="background: #ffa6c9;" | 1,070,400 | style="background: #ffa6c9;" | 1,882,700 | style="background: #fbec5d;" | 185,520 | style="background: #fbec5d;" | 237,948 | style="background: #fbec5d;" | 294,619 | style="background: #fbec5d;" | 377,396 | style="background: #fbec5d;" | 527,108 |
| style="background: #fffdd0;" | Mean radius
| style="background: #fffdd0;" | km | style="background: #b0e0e6;" | 1,737.1 | style="background: #ffa6c9;" | 1,815 | style="background: #ffa6c9;" | 1,569 | style="background: #ffa6c9;" | 2,634.1 | style="background: #ffa6c9;" | 2,410.3 | style="background: #fbec5d;" | 198.30 | style="background: #fbec5d;" | 252.1 | style="background: #fbec5d;" | 533 | style="background: #fbec5d;" | 561.7 | style="background: #fbec5d;" | 764.3 |
| style="background: #fffdd0;" | Surface area{{ref label|A|a|none}}
| style="background: #fffdd0;" | 1{{e|6}} km2 | style="background: #b0e0e6;" | 37.93 | style="background: #ffa6c9;" | 41.910 | style="background: #ffa6c9;" | 30.9 | style="background: #ffa6c9;" | 87.0 | style="background: #ffa6c9;" | 73 | style="background: #fbec5d;" | 0.49 | style="background: #fbec5d;" | 0.799 | style="background: #fbec5d;" | 3.57 | style="background: #fbec5d;" | 3.965 | style="background: #fbec5d;" | 7.337 |
| style="background: #fffdd0;" | Volume{{ref label|B|b|none}}
| style="background: #fffdd0;" | 1{{e|9}} km3 | style="background: #b0e0e6;" | 22 | style="background: #ffa6c9;" | 25.3 | style="background: #ffa6c9;" | 15.9 | style="background: #ffa6c9;" | 76 | style="background: #ffa6c9;" | 59 | style="background: #fbec5d;" | 0.033 | style="background: #fbec5d;" | 0.067 | style="background: #fbec5d;" | 0.63 | style="background: #fbec5d;" | 0.8 | style="background: #fbec5d;" | 1.9 |
| style="background: #fffdd0;" | Mass
| style="background: #fffdd0;" | 1{{e|22}} kg | style="background: #b0e0e6;" | 7.3477 | style="background: #ffa6c9;" | 8.94 | style="background: #ffa6c9;" | 4.80 | style="background: #ffa6c9;" | 14.819 | style="background: #ffa6c9;" | 10.758 | style="background: #fbec5d;" | 0.00375 | style="background: #fbec5d;" | 0.0108 | style="background: #fbec5d;" | 0.06174 | style="background: #fbec5d;" | 0.1095 | style="background: #fbec5d;" | 0.2306 |
| style="background: #fffdd0;" | Density{{ref label|C|c|none}}
| style="background: #fffdd0;" | g/cm3 | style="background: #b0e0e6;" | 3.3464 | style="background: #ffa6c9;" | 3.528 | style="background: #ffa6c9;" | 3.01 | style="background: #ffa6c9;" | 1.936 | style="background: #ffa6c9;" | 1.83 | style="background: #fbec5d;" | 1.15 | style="background: #fbec5d;" | 1.61 | style="background: #fbec5d;" | 0.98 | style="background: #fbec5d;" | 1.48 | style="background: #fbec5d;" | 1.23 |
| style="background: #fffdd0;" | Equatorial gravity{{ref label|D|d|none}}
| style="background: #fffdd0;" | m/s2 | style="background: #b0e0e6;" | 1.622 | style="background: #ffa6c9;" | 1.796 | style="background: #ffa6c9;" | 1.314 | style="background: #ffa6c9;" | 1.428 | style="background: #ffa6c9;" | 1.235 | style="background: #fbec5d;" | 0.0636 | style="background: #fbec5d;" | 0.111 | style="background: #fbec5d;" | 0.145 | style="background: #fbec5d;" | 0.231 | style="background: #fbec5d;" | 0.264 |
| style="background: #fffdd0;" | Escape velocity{{ref label|E|e|none}}
| style="background: #fffdd0;" | km/s | style="background: #b0e0e6;" | 2.38 | style="background: #ffa6c9;" | 2.56 | style="background: #ffa6c9;" | 2.025 | style="background: #ffa6c9;" | 2.741 | style="background: #ffa6c9;" | 2.440 | style="background: #fbec5d;" | 0.159 | style="background: #fbec5d;" | 0.239 | style="background: #fbec5d;" | 0.393 | style="background: #fbec5d;" | 0.510 | style="background: #fbec5d;" | 0.635 |
| style="background: #fffdd0;" | Rotation period
| style="background: #fffdd0;" | days{{ref label|G|g|none}} | style="background: #b0e0e6;" | 27.321582 | style="background: #ffa6c9;" | 1.7691378 | style="background: #ffa6c9;" | 3.551181 | style="background: #ffa6c9;" | 7.154553 | style="background: #ffa6c9;" | 16.68902 | style="background: #fbec5d;" | 0.942422 | style="background: #fbec5d;" | 1.370218 | style="background: #fbec5d;" | 1.887802 | style="background: #fbec5d;" | 2.736915 | style="background: #fbec5d;" | 4.518212 |
| style="background: #fffdd0;" | Orbital period about primary
| style="background: #fffdd0;" | days{{ref label|G|g|none}} | style="background: #b0e0e6;" | 27.32158 | style="background: #ffa6c9;" | 1.769138 | style="background: #ffa6c9;" | 3.551181 | style="background: #ffa6c9;" | 7.154553 | style="background: #ffa6c9;" | 16.68902 | style="background: #fbec5d;" | 0.942422 | style="background: #fbec5d;" | 1.370218 | style="background: #fbec5d;" | 1.887802 | style="background: #fbec5d;" | 2.736915 | style="background: #fbec5d;" | 4.518212 |
| style="background: #fffdd0;" | Mean orbital speed{{ref label|O|o|none}}
| style="background: #fffdd0;" | km/s | style="background: #b0e0e6;" | 1.022 | style="background: #ffa6c9;" | 17.34 | style="background: #ffa6c9;" | 13.740 | style="background: #ffa6c9;" | 10.880 | style="background: #ffa6c9;" | 8.204 | style="background: #fbec5d;" | 14.32 | style="background: #fbec5d;" | 12.63 | style="background: #fbec5d;" | 11.35 | style="background: #fbec5d;" | 10.03 | style="background: #fbec5d;" | 8.48 |
| colspan="2" style="background: #fffdd0;" | Eccentricity
| style="background: #b0e0e6;" | 0.0549 | style="background: #ffa6c9;" | 0.0041 | style="background: #ffa6c9;" | 0.009 | style="background: #ffa6c9;" | 0.0013 | style="background: #ffa6c9;" | 0.0074 | style="background: #fbec5d;" | 0.0202 | style="background: #fbec5d;" | 0.0047 | style="background: #fbec5d;" | 0.02 | style="background: #fbec5d;" | 0.002 | style="background: #fbec5d;" | 0.001 |
| style="background: #fffdd0;" | Inclination to primary's equator
| style="background: #fffdd0;" | deg. | style="background: #b0e0e6;" | 18.29–28.58 | style="background: #ffa6c9;" | 0.04 | style="background: #ffa6c9;" | 0.47 | style="background: #ffa6c9;" | 1.85 | style="background: #ffa6c9;" | 0.2 | style="background: #fbec5d;" | 1.51 | style="background: #fbec5d;" | 0.02 | style="background: #fbec5d;" | 1.51 | style="background: #fbec5d;" | 0.019 | style="background: #fbec5d;" | 0.345 |
| style="background: #fffdd0;" | Axial tilt{{ref label|I|i|none}}{{ref label|U|u|none}}
| style="background: #fffdd0;" | deg. | style="background: #b0e0e6;" | 6.68 | style="background: #ffa6c9;" | 0.000405 | style="background: #ffa6c9;" | 0.0965 | style="background: #ffa6c9;" | ≈ 0–2{{ref label|AA|aa|none}} | style="background: #fbec5d;" | ≈ 0 | style="background: #fbec5d;" | ≈ 0 | style="background: #fbec5d;" | ≈ 0 | style="background: #fbec5d;" | ≈ 0 | style="background: #fbec5d;" | ≈ 0 |
| style="background: #fffdd0;" | Mean surface temperature{{ref label|W|w|none}}
| style="background: #fffdd0;" | K | style="background: #b0e0e6;" | 220 | style="background: #ffa6c9;" | 130 | style="background: #ffa6c9;" | 102 | style="background: #ffa6c9;" | 110{{cite journal |first1=Glenn S. |last1=Orton |first2=John R. |last2=Spencer |first3=Larry D. |last3=Travis |display-authors=3 |first4=Terry Z. |last4=Martin |first5=Leslie K. |last5=Tamppari |title=Galileo Photopolarimeter-radiometer observations of Jupiter and the Galilean Satellites |journal=Science |date=1996 |volume=274 |issue=5286 |pages=389–391 |bibcode=1996Sci...274..389O |doi=10.1126/science.274.5286.389 |s2cid=128624870 }} | style="background: #ffa6c9;" | 134 | style="background: #fbec5d;" | 64 | style="background: #fbec5d;" | 75 | style="background: #fbec5d;" | 64 | style="background: #fbec5d;" | 87 | style="background: #fbec5d;" | 76 |
| colspan="2" style="background: #fffdd0;" | Atmospheric composition
| style="background: #b0e0e6;" | Ar, He | style="background: #ffa6c9;" | SO2{{cite journal |date=1979 |title=Identification of gaseous SO2 and new upper limits for other gases on Io |journal=Nature |volume=288 |issue=5725 |page=755 |doi=10.1038/280755a0 |bibcode=1979Natur.280..755P |first1=John C. |last1=Pearl |last2=Hanel |first2=Rudolf A. |last3=Kunde |first3=Virgil G. |display-authors=3 |last4=Maguire |first4=William C. |last5=Fox |first5=Kenneth |last6=Gupta |first6=Subhash |last7=Ponnamperuma |first7=Cyril |last8=Raulin |first8=François |s2cid=4338190 |doi-access=free }} | style="background: #ffa6c9;" | O2{{Cite journal|last1=Hall|first1=D. T.|last2=Strobel|first2=D. F.|last3=Feldman|first3=P. D.|last4=McGrath|first4=M. A.|last5=Weaver|first5=H. A.|date=February 1995|title=Detection of an oxygen atmosphere on Jupiter's moon Europa|url=https://www.nature.com/articles/373677a0|journal=Nature|language=en|volume=373|issue=6516|pages=677–679|doi=10.1038/373677a0|pmid=7854447|bibcode=1995Natur.373..677H|s2cid=4258306|issn=1476-4687|access-date=1 January 2023|archive-date=1 January 2023|archive-url=https://web.archive.org/web/20230101070328/https://www.nature.com/articles/373677a0|url-status=live|url-access=subscription}} | style="background: #ffa6c9;" | O2{{cite journal|first1=Doyle T. |last1=Hall |first2=Paul D. |last2=Feldman |first3=Melissa A. |last3=McGrath |first4=Darrell F. |last4=Strobel |date=1998 |title=The Far-Ultraviolet Oxygen Airglow of Europa and Ganymede |journal=The Astrophysical Journal |volume=499 |issue=1 |pages=475–481 |doi=10.1086/305604 |bibcode=1998ApJ...499..475H |doi-access=free}} Retrieved 2008-11-17. | style="background: #ffa6c9;" | O2, CO2{{cite journal|date=2005|title=Atmosphere of Callisto|journal=Journal of Geophysical Research|volume=110|issue=E02003|doi=10.1029/2004JE002322|pages=E02003|bibcode= 2005JGRE..110.2003L|first1=Mao-Chang |last1=Liang |first2=Benjamin F. |last2=Lane |first3=Robert T. |last3=Pappalardo |display-authors=3 |first4=Mark |last4=Allen |first5=Yuk L. |last5=Yung |doi-access=free}} Retrieved 2008-11-17. | style="background: #fbec5d;" | | style="background: #fbec5d;" | H2O, N2 |last1=Waite |first1=J. Hunter Jr. |last2=Combi |first2=Michael R. |author3-link=Ip Wing-huen |last3=Ip |first3=Wing-Huen |display-authors=3 |last4=Cravens |first4=Thomas E. |last5=McNutt |first5=Ralph L. Jr. |last6=Kasprzak |first6=Wayne T. |last7=Yelle |first7=Roger V. |last8=Luhmann |first8=Janet |last9=Niemann |first9=Hasso B. |first10=David |last10=Gell |first11=Brian |last11=Magee |first12=Greg |last12=Fletcher |first13=Jonathan I. |last13=Lunine |first14=Wei-Ling |last14=Tseng |s2cid=3032849 |date=2006 |title=Cassini Ion and Neutral Mass Spectrometer: Enceladus Plume Composition and Structure |journal=Science |volume=311 |issue=5766 |pages=1419–1422 |doi=10.1126/science.1121290 |pmid=16527970 |bibcode=2006Sci...311.1419W}} Retrieved 2008-11-17. | style="background: #fbec5d;" | | style="background: #fbec5d;" | | style="background: #fbec5d;" | |
| class="wikitable" style="text-align: center;" |
| colspan="2" rowspan=2 |
! style="background: #fbec5d;" | ♄Titan{{ref label|P|p|none}} ! style="background: #fbec5d;" | ♄Iapetus{{ref label|P|p|none}} ! style="background: #7fffd4;" | ⛢Miranda{{ref label|R|r|none}} ! style="background: #7fffd4;" | ⛢Ariel{{ref label|R|r|none}} ! style="background: #7fffd4;" | ⛢Umbriel{{ref label|R|r|none}} ! style="background: #7fffd4;" | ⛢Titania{{ref label|R|r|none}} ! style="background: #7fffd4;" | ⛢Oberon{{ref label|R|r|none}} ! style="background: azure;" | ♆Triton{{Cite web|last=Williams|first=David R.|year=2016|title=Neptunian Satellite Fact Sheet|url=https://nssdc.gsfc.nasa.gov/planetary/factsheet/neptuniansatfact.html|access-date=2023-01-01|website=NASA|archive-date=26 October 2000|archive-url=https://web.archive.org/web/20001026193243/http://nssdc.gsfc.nasa.gov/planetary/factsheet/neptuniansatfact.html|url-status=live}} ! style="background: #ccf;" | ♇Charon |
|---|
| style="background: black;" | x70px
| style="background: black;" | 70x70px | style="background: black;" | x70px | style="background: black;" | x70px | style="background: black;" | x70px | style="background: black;" | x70px | style="background: black;" | x70px | style="background: black;" | 70x70px | style="background: black;" | 70x70px |
| style="background: #fffdd0;" colspan=2 | Roman numeral designation
| style="background: #fbec5d;" | Saturn VI | style="background: #fbec5d;" | Saturn VIII | style="background: #7fffd4;" | Uranus V | style="background: #7fffd4;" | Uranus I | style="background: #7fffd4;" | Uranus II | style="background: #7fffd4;" | Uranus III | style="background: #7fffd4;" | Uranus IV | style="background: azure;" | Neptune I | style="background: #ccf;" | Pluto I |
| style="background: #fffdd0;" colspan=2 | Symbol
| style="background: #fbec5d;" | SVI | style="background: #fbec5d;" | SVIII | style="background: #7fffd4;" | UV | style="background: #7fffd4;" | UI | style="background: #7fffd4;" | UII | style="background: #7fffd4;" | UIII | style="background: #7fffd4;" | UIV | style="background: azure;" | NI | style="background: #ccf;" | PI |
| colspan="2" style="background: #fffdd0;" | Discovery year
| style="background: #fbec5d;" | 1655 | style="background: #fbec5d;" | 1671 | style="background: #7fffd4;" | 1948 | style="background: #7fffd4;" | 1851 | style="background: #7fffd4;" | 1851 | style="background: #7fffd4;" | 1787 | style="background: #7fffd4;" | 1787 | style="background: azure;" | 1846 | style="background: #ccf;" | 1978 |
| style="background: #fffdd0;" | Mean distance from primary | style="background: #fffdd0;" | km | style="background: #fbec5d;" | 1,221,870 | style="background: #fbec5d;" | 3,560,820 | style="background: #7fffd4;" | 129,390 | style="background: #7fffd4;" | 190,900 | style="background: #7fffd4;" | 266,000 | style="background: #7fffd4;" | 436,300 | style="background: #7fffd4;" | 583,519 | style="background: azure;" | 354,759 | style="background: #ccf;" | 17,536 |
| style="background: #fffdd0;" | Mean radius
| style="background: #fffdd0;" | km | style="background: #fbec5d;" | 2,576 | style="background: #fbec5d;" | 735.60 | style="background: #7fffd4;" | 235.8 | style="background: #7fffd4;" | 578.9 | style="background: #7fffd4;" | 584.7 | style="background: #7fffd4;" | 788.9 | style="background: #7fffd4;" | 761.4 | style="background: azure;" | 1,353.4 | style="background: #ccf;" | 603.5 |
| style="background: #fffdd0;" | Surface area{{ref label|A|a|none}}
| style="background: #fffdd0;" | 1{{e|6}} km2 | style="background: #fbec5d;" | 83.0 | style="background: #fbec5d;" | 6.7 | style="background: #7fffd4;" | 0.70 | style="background: #7fffd4;" | 4.211 | style="background: #7fffd4;" | 4.296 | style="background: #7fffd4;" | 7.82 | style="background: #7fffd4;" | 7.285 | style="background: azure;" | 23.018 | style="background: #ccf;" | 4.580 |
| style="background: #fffdd0;" | Volume{{ref label|B|b|none}}
| style="background: #fffdd0;" | 1{{e|9}} km3 | style="background: #fbec5d;" | 71.6 | style="background: #fbec5d;" | 1.67 | style="background: #7fffd4;" | 0.055 | style="background: #7fffd4;" | 0.81 | style="background: #7fffd4;" | 0.84 | style="background: #7fffd4;" | 2.06 | style="background: #7fffd4;" | 1.85 | style="background: azure;" | 10 | style="background: #ccf;" | 0.92 |
| style="background: #fffdd0;" | Mass
| style="background: #fffdd0;" | 1{{e|22}} kg | style="background: #fbec5d;" | 13.452 | style="background: #fbec5d;" | 0.18053 | style="background: #7fffd4;" | 0.00659 | style="background: #7fffd4;" | 0.135 | style="background: #7fffd4;" | 0.12 | style="background: #7fffd4;" | 0.35 | style="background: #7fffd4;" | 0.3014 | style="background: azure;" | 2.14 | style="background: #ccf;" | 0.152 |
| style="background: #fffdd0;" | Density{{ref label|C|c|none}}
| style="background: #fffdd0;" | g/cm3 | style="background: #fbec5d;" | 1.88 | style="background: #fbec5d;" | 1.08 | style="background: #7fffd4;" | 1.20 | style="background: #7fffd4;" | 1.67 | style="background: #7fffd4;" | 1.40 | style="background: #7fffd4;" | 1.72 | style="background: #7fffd4;" | 1.63 | style="background: azure;" | 2.061 | style="background: #ccf;" | 1.65 |
| style="background: #fffdd0;" | Equatorial gravity{{ref label|D|d|none}}
| style="background: #fffdd0;" | m/s2 | style="background: #fbec5d;" | 1.35 | style="background: #fbec5d;" | 0.22 | style="background: #7fffd4;" | 0.08 | style="background: #7fffd4;" | 0.27 | style="background: #7fffd4;" | 0.23 | style="background: #7fffd4;" | 0.39 | style="background: #7fffd4;" | 0.35 | style="background: azure;" | 0.78 | style="background: #ccf;" | 0.28 |
| style="background: #fffdd0;" | Escape velocity{{ref label|E|e|none}}
| style="background: #fffdd0;" | km/s | style="background: #fbec5d;" | 2.64 | style="background: #fbec5d;" | 0.57 | style="background: #7fffd4;" | 0.19 | style="background: #7fffd4;" | 0.56 | style="background: #7fffd4;" | 0.52 | style="background: #7fffd4;" | 0.77 | style="background: #7fffd4;" | 0.73 | style="background: azure;" | 1.46 | style="background: #ccf;" | 0.58 |
| style="background: #fffdd0;" | Rotation period
| style="background: #fffdd0;" | days{{ref label|G|g|none}} | style="background: #fbec5d;" | 15.945 | style="background: #fbec5d;" | 79.322 | style="background: #7fffd4;" | 1.414 | style="background: #7fffd4;" | 2.52 | style="background: #7fffd4;" | 4.144 | style="background: #7fffd4;" | 8.706 | style="background: #7fffd4;" | 13.46 | style="background: azure;" | 5.877 | style="background: #ccf;" | 6.387 |
| style="background: #fffdd0;" | Orbital period about primary
| style="background: #fffdd0;" | days | style="background: #fbec5d;" | 15.945 | style="background: #fbec5d;" | 79.322 | style="background: #7fffd4;" | 1.4135 | style="background: #7fffd4;" | 2.520 | style="background: #7fffd4;" | 4.144 | style="background: #7fffd4;" | 8.706 | style="background: #7fffd4;" | 13.46 | style="background: azure;" | 5.877 | style="background: #ccf;" | 6.387 |
| style="background: #fffdd0;" | Mean orbital speed{{ref label|O|o|none}}
| style="background: #fffdd0;" | km/s | style="background: #fbec5d;" | 5.57 | style="background: #fbec5d;" | 3.265 | style="background: #7fffd4;" | 6.657 | style="background: #7fffd4;" | 5.50898 | style="background: #7fffd4;" | 4.66797 | style="background: #7fffd4;" | 3.644 | style="background: #7fffd4;" | 3.152 | style="background: azure;" | 4.39 | style="background: #ccf;" | 0.2 |
| colspan="2" style="background: #fffdd0;" | Eccentricity
| style="background: #fbec5d;" | 0.0288 | style="background: #fbec5d;" | 0.0286 | style="background: #7fffd4;" | 0.0013 | style="background: #7fffd4;" | 0.0012 | style="background: #7fffd4;" | 0.005 | style="background: #7fffd4;" | 0.0011 | style="background: #7fffd4;" | 0.0014 | style="background: azure;" | 0.00002 | style="background: #ccf;" | 0.0022 |
| style="background: #fffdd0;" | Inclination to primary's equator
| style="background: #fffdd0;" | deg. | style="background: #fbec5d;" | 0.33 | style="background: #fbec5d;" | 14.72 | style="background: #7fffd4;" | 4.22 | style="background: #7fffd4;" | 0.31 | style="background: #7fffd4;" | 0.36 | style="background: #7fffd4;" | 0.14 | style="background: #7fffd4;" | 0.10 | style="background: azure;" | 157{{ref label|H|h|none}} | style="background: #ccf;" | 0.001 |
| style="background: #fffdd0;" | Axial tilt{{ref label|I|i|none}}{{ref label|U|u|none}}
| style="background: #fffdd0;" | deg. | style="background: #fbec5d;" | ≈ 0 | style="background: #7fffd4;" | ≈ 0 | style="background: #7fffd4;" | ≈ 0 | style="background: #7fffd4;" | ≈ 0 | style="background: #7fffd4;" | ≈ 0 | style="background: #7fffd4;" | ≈ 0 | style="background: #ccf;" | ≈ 0 |
| style="background: #fffdd0;" | Mean surface temperature{{ref label|W|w|none}}
| style="background: #fffdd0;" | K | style="background: #fbec5d;" | 93.7{{cite journal |title = Optical Properties of Titan Haze Laboratory Analogs Using Cavity Ring Down Spectroscopy |issue=1376 |page=51 |first1=Christa A. |last1=Hasenkopf |first2=Melinda R. |last2=Beaver |first3=Margaret A. |last3=Tolbert |display-authors=3 |first4=Owen B. |last4=Toon |first5=Christopher P. |last5=McKay |date = 2007 |journal = Workshop on Planetary Atmospheres |url = http://www.lpi.usra.edu/meetings/patm2007/pdf/9034.pdf |access-date = 2007-10-16 |archive-url = https://web.archive.org/web/20140526074847/http://www.lpi.usra.edu/meetings/patm2007/pdf/9034.pdf |archive-date = 2014-05-26 |bibcode=2007plat.work...51H }} | style="background: #fbec5d;" | 130 | style="background: #7fffd4;" | 59 | style="background: #7fffd4;" | 58 | style="background: #7fffd4;" | 61 | style="background: #7fffd4;" | 60 | style="background: #7fffd4;" | 61 | style="background: azure;" | 38{{cite journal | title = Spectroscopic Determination of the Phase Composition and Temperature of Nitrogen Ice on Triton |first1=Kimberly |last1=Tryka |first2=Robert H. |last2=Brown |first3=Vincent |last3=Anicich |display-authors=3 |first4=Dale P. |last4=Cruikshank |first5=Tobias C. |last5=Owen | journal = Science | volume = 261 | issue = 5122 | pages = 751–754 | bibcode = 1993Sci...261..751T |date=August 1993 | doi = 10.1126/science.261.5122.751 | pmid = 17757214 |s2cid=25093997 }} | style="background: #ccf;" | 53 |
| colspan="2" style="background: #fffdd0;" | Atmospheric composition
| style="background: #fbec5d;" | N2, CH4{{cite journal |title=The abundances of constituents of Titan's atmosphere from the GCMS instrument on the Huygens probe |first1=Hasso B. |last1=Niemann |first2=Sushil K. |last2=Atreya |first3=Sven J. |last3=Bauer |display-authors=3 |first4=George R. |last4=Carignan |first5=Jaime E. |last5=Demick |first6=Ray L. |last6=Frost |first7=Daniel |last7=Gautier |first8=John A. |last8=Haberman |first9=Dan N. |last9=Harpold |first10=Donald M. |last10=Hunten |first11=Gianluca |last11=Israel |first12=Jonathan I. |last12=Lunine |first13=Wayne T. |last13=Kasprzak |first14=Tobias C. |last14=Owen |first15=Michael |last15=Paulkovich |first16=François |last16=Raulin |first17=Eric |last17=Raaen |first18=Stanley H. |last18=Way |journal=Nature |volume=438 |issue=7069 |pages=779–784 |date=2005 |pmid=16319830 |doi=10.1038/nature04122 |bibcode=2005Natur.438..779N |hdl=2027.42/62703 |s2cid=4344046 |url=https://deepblue.lib.umich.edu/bitstream/2027.42/62703/1/nature04122.pdf |hdl-access=free |access-date=20 August 2019 |archive-date=14 April 2020 |archive-url=https://web.archive.org/web/20200414035805/https://deepblue.lib.umich.edu/bitstream/handle/2027.42/62703/nature04122.pdf;jsessionid=31739AEF2B6261988585EC558A2F898B?sequence=1 |url-status=live }} | style="background: #fbec5d;" | | style="background: #7fffd4;" | | style="background: #7fffd4;" | | style="background: #7fffd4;" | | style="background: #7fffd4;" | | style="background: #7fffd4;" | | style="background: azure;" | N2, CH4{{cite journal | title = Ultraviolet Spectrometer Observations of Neptune and Triton |first1=A. Lyle |last1=Broadfoot |first2=Sushil K. |last2=Atreya |first3=Jean-Loup |last3=Bertaux |display-authors=3 |first4=Jacques E. |last4=Blamont |first5=Alexander J. |last5=Dessler |first6=Thomas M. |last6=Donahue |first7=William T. |last7=Forrester |first8=Doyle T. |last8=Hall |first9=Floyd |last9=Herbert |first10=Jay B. |last10=Holberg |first11=Deidre M. |last11=Hunter |first12=Vladimir A. |last12=Krasnopolsky |first13=Susan H. |last13=Linick |first14=Jonathan I. |last14=Lunine |first15=John C. |last15=McConnell |first16=H. Warren |last16=Moos |first17=Bill R. |last17=Sandel |first18=Nicholas M. |last18=Schneider |first19=Donald E. |last19=Shemansky |first20=Gerald R. |last20=Smith |first21=DarrellF. |last21=Strobel |first22=Roger V. |last22=Yelle | bibcode = 1989Sci...246.1459B | date = 1989-12-15 | journal = Science | volume = 246 | pages = 1459–1466 | doi = 10.1126/science.246.4936.1459 | pmid = 17756000 | issue = 4936 |s2cid=21809358 }} | style="background: #ccf;" | |
See also
{{div col|colwidth=20em}}
- List of Solar System objects by size
- Lists of astronomical objects
- List of former planets
- Planetary-mass object
{{div col end}}
Notes
{{refbegin}}
= Unless otherwise cited{{ref label|Z|z|none}} =
{{ordered list|type=a
| item1_value = 15 | 1 = {{note label|O|o|none}} The planetary discriminant for the planets is taken from material published by Stephen Soter.{{cite journal |title=What is a Planet? |first=Stephen |last=Soter |date=2006-08-16 |journal=The Astronomical Journal |volume=132 |issue=6 |pages=2513–2519 |arxiv=astro-ph/0608359 |doi=10.1086/508861 |bibcode=2006AJ....132.2513S |s2cid=14676169 }} Planetary discriminants for Ceres, Pluto and Eris taken from Soter, 2006. Planetary discriminants of all other bodies calculated from the Kuiper belt mass estimate given by Lorenzo Iorio.{{cite journal |title=Dynamical determination of the mass of the Kuiper Belt from motions of the inner planets of the Solar system |first=Lorenzo |last=Iorio |journal=Monthly Notices of the Royal Astronomical Society |volume=375 |issue=4 |pages=1311–1314 |bibcode=2007MNRAS.375.1311I |date=March 2007 |doi=10.1111/j.1365-2966.2006.11384.x |doi-access=free |arxiv=gr-qc/0609023 |s2cid=16605188 }}
| item2_value = 16 | 2 = {{note label|P|p|none}}Saturn satellite info taken from NASA Saturnian Satellite Fact Sheet.{{Cite web|title=Saturnian Satellite Fact Sheet|url=https://nssdc.gsfc.nasa.gov/planetary/factsheet/saturniansatfact.html|access-date=2023-01-01|website=nssdc.gsfc.nasa.gov|archive-date=9 May 2019|archive-url=https://web.archive.org/web/20190509051559/https://nssdc.gsfc.nasa.gov/planetary/factsheet/saturniansatfact.html|url-status=live}}
| item3_value = 17 | 3 = {{note label|Q|q|none}}With the exception of the Sun and Earth symbols, astronomical symbols are mostly used by astrologers today; although occasional use of the other symbols in astronomical contexts still exists, it is officially discouraged.
{{cite book
| title = The IAU Style Manual
| date = 1989
| page = 27
| publisher=The International Astrophysical Union
| url = https://www.iau.org/static/publications/stylemanual1989.pdf
| access-date = August 20, 2018 | url-status=live
| archive-url=https://web.archive.org/web/20180621194133/https://www.iau.org/static/publications/stylemanual1989.pdf
| archive-date=June 21, 2018
}}
All symbols encoded in Unicode have been included.
- Astronomical symbols for the Sun, the planets (first symbol for Uranus), and the Moon, as well as the first symbol for Pluto were taken from NASA Solar System Exploration.{{cite web |url=http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=167 |archive-url=https://web.archive.org/web/20031216235302/http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=167 |archive-date=2003-12-16 |title=NASA Solar System Exploration: Planet Symbols |publisher=NASA |access-date=2009-01-26}}
- The symbol for Ceres, as well as the second symbol for Uranus, was taken from material published by James L. Hilton.{{cite web |first=James L. |last=Hilton |title=When did asteroids become minor planets? |work=U.S. Naval Observatory |url=http://sd-www.jhuapl.edu/weaver_projects/GPD/Contributed_Talks/hilton_gpd_poster.pdf |access-date=2008-10-25 |archive-date=17 December 2008 |archive-url=https://web.archive.org/web/20081217034516/http://sd-www.jhuapl.edu/weaver_projects/GPD/Contributed_Talks/hilton_gpd_poster.pdf |url-status=live }}
- The other dwarf-planet symbols were invented by Denis Moskowitz, a software engineer in Massachusetts. His symbols for Haumea, Makemake, and Eris appear in a NASA JPL infographic, as does the second symbol for Pluto.{{cite web |url= https://www.jpl.nasa.gov/infographics/what-is-a-dwarf-planet |author= JPL/NASA |date= April 22, 2015 |website= Jet Propulsion Laboratory |title= What is a Dwarf Planet? |access-date= 2021-09-24 |archive-date= 8 December 2021 |archive-url= https://web.archive.org/web/20211208181916/https://www.jpl.nasa.gov/infographics/what-is-a-dwarf-planet |url-status= live }} His symbols for Quaoar, Sedna, Orcus, and Gonggong were taken from Unicode; his symbol for Salacia is mentioned in two Unicode proposals, but has not been included.{{Cite web|url=https://www.unicode.org/L2/L2021/21224-dwarf-planet-syms.pdf|title=L2/21-224: Unicode request for dwarf-planet symbols|access-date=29 November 2021|archive-date=23 March 2022|archive-url=https://web.archive.org/web/20220323174107/https://www.unicode.org/L2/L2021/21224-dwarf-planet-syms.pdf|url-status=live}}{{cite web |url=https://www.unicode.org/L2/L2024/24235-constellation-symbols.pdf |title=Preliminary presentation of constellation symbols |last=Miller |first=Kirk |date=18 October 2024 |website=unicode.org |publisher=The Unicode Consortium |access-date=22 October 2024 |quote=}}
The Moon is the only natural satellite with a standard abstract symbol; abstract symbols have been proposed for the others, but have not received significant astronomical or astrological use or mention.{{cite web |url=https://www.unicode.org/L2/L2025/25079-phobos-and-deimos.pdf |title=Phobos and Deimos symbols |last1=Bala |first1=Gavin Jared |last2=Miller |first2=Kirk |date=7 March 2025 |website=unicode.org |publisher=The Unicode Consortium |access-date=14 March 2025 |quote=}} The others are often referred to with the initial letter of their parent planet and their Roman numeral.
| item4_value = 18 | 4 = {{note label|R|r|none}}Uranus satellite info taken from NASA Uranian Satellite Fact Sheet.{{cite web|url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/uraniansatfact.html|title=NASA Uranian Satellite Fact Sheet|publisher=NASA|access-date=2008-11-17|archive-url=https://web.archive.org/web/20100105183741/http://nssdc.gsfc.nasa.gov/planetary/factsheet/uraniansatfact.html|archive-date=2010-01-05}}
| item5_value = 19 | 5 = {{note label|S|s|none}}Radii for plutoid candidates taken from material published by John A. Stansberry et al.
| item6_value = 21 | 6 = {{note label|U|u|none}}Axial tilts for most satellites assumed to be zero in accordance with the Explanatory Supplement to the Astronomical Almanac: "In the absence of other information, the axis of rotation is assumed to be normal to the mean orbital plane."{{cite book |title=Explanatory Supplement to the Astronomical Almanac |editor-first=P. Kenneth |editor-last=Seidelmann |publisher=University Science Books |date=1992 |page=384 }}
| item7_value = 22 | 7 = {{note label|V|v|none}}Natural satellite numbers taken from material published by Scott S. Sheppard.{{cite web |title=The Jupiter Satellite Page |first=Scott S. |last=Sheppard |work=Carnegie Institution for Science, Department of Terrestrial Magnetism |url=http://www.dtm.ciw.edu/users/sheppard/satellites |access-date=2008-04-02 |archive-url=https://web.archive.org/web/20130313184354/http://www.dtm.ciw.edu/users/sheppard/satellites/ |archive-date=2013-03-13 }}
}}
= Manual calculations (unless otherwise cited) =
{{ordered list|type=a
| item1_value = 1 | 1 = {{note label|A|a|none}} Surface area A derived from the radius using , assuming sphericity.
| item2_value = 2 | 2 = {{note label|B|b|none}} Volume V derived from the radius using , assuming sphericity.
| item3_value = 3 | 3 = {{note label|C|c|none}} Density derived from the mass divided by the volume.
| item4_value = 4 | 4 = {{note label|D|d|none}} Surface gravity derived from the mass m, the gravitational constant G and the radius r: Gm/r2.
| item5_value = 5 | 5 = {{note label|E|e|none}} Escape velocity derived from the mass m, the gravitational constant G and the radius r: {{radic|(2Gm)/r}}.
| item6_value = 14 | 6 = {{note label|N|n|none}} Orbital speed is calculated using the mean orbital radius and the orbital period, assuming a circular orbit.
| item7_value = 20 | 7 = {{note label|T|t|none}} Assuming a density of 2.0
| item8_value = 23 | 8 = {{note label|W|w|none}} Calculated using the formula where Teff = 54.8 K at 52 AU, is the geometric albedo, q = 0.8 is the phase integral, and is the distance from the Sun in AU. This formula is a simplified version of that in section 2.2 of Stansberry et al., 2007, where emissivity and beaming parameter were assumed to equal unity, and was replaced with 4, accounting for the difference between circle and sphere. All parameters mentioned above were taken from the same paper.
}}
= Individual calculations =
{{ordered list|type=a
| item1_value = 25 | 1 = {{note label|Y|y|none}} Surface area was calculated using the formula for a scalene ellipsoid:
: where is the modular angle, or angular eccentricity; and , are the incomplete elliptic integrals of the first and second kind, respectively. The values 980 km, 759 km, and 498 km were used for a, b, and c respectively.
}}
= Other notes =
{{ordered list|type=a
| item1_value = 6 | 1 = {{note label|F|f|none}} Relative to Earth
| item2_value = 7 | 2 = {{note label|G|g|none}} Sidereal
| item3_value = 8 | 3 = {{note label|H|h|none}} Retrograde
| item4_value = 9 | 4 = {{note label|I|i|none}} The inclination of the body's equator from its orbit.
| item5_value = 10 | 5 = {{note label|J|j|none}} At pressure of 1 bar
| item6_value = 11 | 6 = {{note label|K|k|none}} At sea level
| item7_value = 12 | 7 = {{note label|L|l|none}} The ratio between the mass of the object and those in its immediate neighborhood. Used to distinguish between a planet and a dwarf planet.
| item8_value = 13 | 8 = {{note label|M|m|none}} This object's rotation is synchronous with its orbital period, meaning that it only ever shows one face to its primary.
| item9_value = 24 | 9 = {{note label|X|x|none}} Objects' planetary discriminants based on their similar orbits to Eris. Sedna's population is currently too little-known for a planetary discriminant to be determined.
| item10_value = 26 | 10 = {{note label|Z|z|none}} "Unless otherwise cited" means that the information contained in the citation is applicable to an entire line or column of a chart, unless another citation specifically notes otherwise. For example, Titan's mean surface temperature is cited to the reference in its cell; it is not calculated like the temperatures of most of the other satellites here, because it has an atmosphere that makes the formula inapplicable.
| item11_value = 27 | 11 = {{note label|AA|aa|none}} Callisto's axial tilt varies between 0 and about 2 degrees on timescales of thousands of years.}}
{{refend}}
References
{{reflist|30em}}
{{Solar System}}
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