# Ice planet

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Planet with an icy surface

This article is about the type of planet smaller than giant planets. For the film, see [Ice Planet (film)](/source/Ice_Planet_(film)). For the type of giant planet, see [ice giant](/source/Ice_giant).

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[Ganymede](/source/Ganymede_(moon)), the largest known solid icy body in the Solar System

An **ice planet** or **icy planet** is a type of [planet](/source/Planet) with an icy surface of [volatiles](/source/Volatile_(astrogeology)) such as [water](/source/Water), [ammonia](/source/Ammonia), and [methane](/source/Methane). Ice planets consist of a global [cryosphere](/source/Cryosphere).

Under a [geophysical definition of planet](/source/Geophysical_definition_of_planet), the small icy worlds of the [Solar System](/source/Solar_System) qualify as icy planets. These include most of the [planetary-mass moons](/source/Planetary-mass_moon), such as [Ganymede](/source/Ganymede_(moon)), [Titan](/source/Titan_(moon)), [Europa](/source/Europa_(moon)), [Enceladus](/source/Enceladus_(moon)), and [Triton](/source/Triton_(moon)); [dwarf planets](/source/Dwarf_planet) [Pluto](/source/Pluto), [Orcus](/source/Orcus_(dwarf_planet)), [Haumea](/source/Haumea), [Makemake](/source/Makemake_(dwarf_planet)), [Quaoar](/source/Quaoar), [Sedna](/source/Sedna_(dwarf_planet)), [Gonggong](/source/Gonggong_(dwarf_planet)), and [Eris](/source/Eris_(dwarf_planet)); and the largest [comets](/source/Comet). In June 2020, [NASA scientists](/source/NASA) reported that it is likely that [exoplanets](/source/Exoplanet) with oceans, including some with oceans that may lie beneath a layer of surface ice, may be common in the [Milky Way galaxy](/source/Milky_Way), based on [mathematical modeling studies](/source/Mathematical_model).[1][2] [OGLE-2005-BLG-390Lb](/source/OGLE-2005-BLG-390Lb), first observed in 2005, is a possible ice planet.

## Characteristics and habitability

OGLE-2005-BLG-390Lb (artist's impression) is an example of likely ice planet

OGLE-2013-BLG-0341LB b (artist's impression)

An ice planet's surface can be composed of [water](/source/Water), [methane](/source/Methane), [ammonia](/source/Ammonia), [carbon dioxide](/source/Carbon_dioxide) (known as "[dry ice](/source/Dry_ice)"), [carbon monoxide](/source/Carbon_monoxide), [nitrogen](/source/Nitrogen), and other volatiles, depending on its surface temperature. Ice planets would have surface temperatures below 260 [K](/source/Kelvin) (−13 °C) if composed primarily of [water](/source/Water), below 180 K (−93 °C) if primarily composed of CO2 and [ammonia](/source/Ammonia), and below 80 K (−193 °C) if composed primarily of methane.

On the surface, ice planets are hostile to life forms like those living on Earth because they are extremely cold. Many ice worlds likely have [subsurface oceans](/source/Subsurface_ocean), warmed by [internal heat](/source/Internal_heat) or [tidal forces](/source/Tidal_force) from another nearby body. [3][4] Liquid subsurface water would provide habitable conditions for [life](/source/Extraterrestrial_life), including [fish](/source/Fish), [plankton](/source/Plankton), and [microorganisms](/source/Microorganism). Subsurface plants as we know them could not exist because there is no sunlight to use for [photosynthesis](/source/Photosynthesis). Microorganisms can produce nutrients using specific chemicals ([chemosynthesis](/source/Chemosynthesis)) that may provide food and energy for other organisms. Some planets, if conditions are right, may have significant atmospheres and surface liquids like Saturn's moon [Titan](/source/Titan_(moon)), which could be habitable for [exotic forms of life](/source/Hypothetical_types_of_biochemistry).

## Examples

### In solar system

Although there are many icy objects in the [Solar System](/source/Solar_System), none of them qualify as planets under the [IAU definition of planet](/source/IAU_definition_of_planet). However, most [planetary-mass moons](/source/Planetary-mass_moon) are ice-rock (e.g. [Ganymede](/source/Ganymede_(moon)), [Callisto](/source/Callisto_(moon)), [Enceladus](/source/Enceladus), [Titan](/source/Titan_(moon)), and [Triton](/source/Triton_(moon))) or even primarily ice (e.g. [Mimas](/source/Mimas_(moon)), [Tethys](/source/Tethys_(moon)), [Rhea](/source/Rhea_(moon)), and [Iapetus](/source/Iapetus_(moon))) and so qualify as ice planets under [geophysical definitions](/source/Geophysical_definition_of_planet) of the term. The largest [Kuiper belt](/source/Kuiper_belt) objects, such as [Pluto](/source/Pluto), [Haumea](/source/Haumea), [Makemake](/source/Makemake_(dwarf_planet)), [Charon](/source/Charon_(moon)), [Quaoar](/source/Quaoar), and [Orcus](/source/Orcus_(dwarf_planet))[5] also qualify as such under geophysical definitions. [Europa](/source/Europa_(moon)) is also often considered an ice planet due to its surface ice, though its high density indicates that its interior is mostly rocky. The same is true for the scattered-disc object [Eris](/source/Eris_(dwarf_planet)).[6]

### Beyond solar system

Dozens of known exoplanets are very probably ice planets, given their orbits, surfaces, densities, and host stars. Examples of ice planets include [Gliese 667 C d](/source/Gliese_667_C_d), [Gliese 667 C g](/source/Gliese_667_C_g), [Kepler-441b](https://en.wikipedia.org/w/index.php?title=Kepler-441b&action=edit&redlink=1), [OGLE-2005-BLG-390Lb](/source/OGLE-2005-BLG-390Lb), [OGLE-2013-BLG-0341LBb](https://en.wikipedia.org/w/index.php?title=OGLE-2013-BLG-0341LBb&action=edit&redlink=1), [OGLE-2016-BLG-1195Lb](/source/OGLE-2016-BLG-1195Lb) and [MOA-2007-BLG-192Lb](/source/MOA-2007-BLG-192Lb)[7][8]

## See also

- [Ice giant](/source/Ice_giant)

- [Icy moon](/source/Icy_moon)

- [Ocean world](/source/Ocean_world)

- [Snowball Earth](/source/Snowball_Earth)

- [Hoth](/source/Hoth) – Fictional planet in Star Wars

## References

1. **[^](#cite_ref-EA-20200618_1-0)** [NASA](/source/NASA) (18 June 2020). ["Are planets with oceans common in the galaxy? It's likely, NASA scientists find"](https://web.archive.org/web/20200621020131/https://www.eurekalert.org/pub_releases/2020-06/nsfc-apw061820.php). *[EurekAlert!](/source/EurekAlert!)*. Archived from [the original](https://www.eurekalert.org/pub_releases/2020-06/nsfc-apw061820.php) on 21 June 2020. Retrieved 20 June 2020.

1. **[^](#cite_ref-NASA-20200618_2-0)** Shekhtman, Lonnie; et al. (18 June 2020). ["Are Planets with Oceans Common in the Galaxy? It's Likely, NASA Scientists Find"](https://www.nasa.gov/feature/goddard/2020/are-planets-with-oceans-common-in-the-galaxy-it-s-likely-nasa-scientists-find). *[NASA](/source/NASA)*. Retrieved 20 June 2020.

1. **[^](#cite_ref-3)** Quick, Lynnae C.; Roberge, Aki.; Mendoza, Guadalupe Tovar; Quintana, Elisa V.; Youngblood, Allison A. (4 October 2023). ["Prospects for Cryovolcanic Activity on Cold Ocean Planets"](https://doi.org/10.3847%2F1538-4357%2Face9b6). *[The Astrophysical Journal](/source/The_Astrophysical_Journal)*. **956** (29): 29. [Bibcode](/source/Bibcode_(identifier)):[2023ApJ...956...29Q](https://ui.adsabs.harvard.edu/abs/2023ApJ...956...29Q). [doi](/source/Doi_(identifier)):[10.3847/1538-4357/ace9b6](https://doi.org/10.3847%2F1538-4357%2Face9b6).

1. **[^](#cite_ref-4)** Quick, Lynnae C.; Roberge, Aki.; Mlinar, Amy Barr; Hedman, Matthew M. (18 June 2020). "Forecasting Rates of Volcanic Activity on Terrestrial Exoplanets and Implications for Cryovolcanic Activity on Extrasolar Ocean Worlds". *[Publications of the Astronomical Society of the Pacific](/source/Publications_of_the_Astronomical_Society_of_the_Pacific)*. **132** (1014). [Bibcode](/source/Bibcode_(identifier)):[2020PASP..132h4402Q](https://ui.adsabs.harvard.edu/abs/2020PASP..132h4402Q). [doi](/source/Doi_(identifier)):[10.1088/1538-3873/ab9504](https://doi.org/10.1088%2F1538-3873%2Fab9504).

1. **[^](#cite_ref-Wiley-2005_5-0)** Stern, Alan; [Mitton, Jacqueline](/source/Jacqueline_Mitton) (2005). ["Pluto and Charon: ice worlds on the ragged edge of the solar system"](http://www.worldcat.org/search?q=isbn%3A3527405569). Weinheim: [Wiley-VCH](/source/Wiley-VCH). Retrieved July 13, 2013.

1. **[^](#cite_ref-planetarysociety_6-0)** Emily Lakdawalla et al., [What Is A Planet?](https://www.planetary.org/worlds/what-is-a-planet) The Planetary Society, 21 April 2020

1. **[^](#cite_ref-7)** Quick, Lynnae C.; Roberge, Aki.; Mendoza, Guadalupe Tovar; Quintana, Elisa V.; Youngblood, Allison A. (4 October 2023). ["Prospects for Cryovolcanic Activity on Cold Ocean Planets"](https://doi.org/10.3847%2F1538-4357%2Face9b6). *[The Astrophysical Journal](/source/The_Astrophysical_Journal)*. **956** (29): 29. [Bibcode](/source/Bibcode_(identifier)):[2023ApJ...956...29Q](https://ui.adsabs.harvard.edu/abs/2023ApJ...956...29Q). [doi](/source/Doi_(identifier)):[10.3847/1538-4357/ace9b6](https://doi.org/10.3847%2F1538-4357%2Face9b6).

1. **[^](#cite_ref-8)** Quick, Lynnae C.; Roberge, Aki.; Mlinar, Amy Barr; Hedman, Matthew M. (18 June 2020). "Forecasting Rates of Volcanic Activity on Terrestrial Exoplanets and Implications for Cryovolcanic Activity on Extrasolar Ocean Worlds". *[Publications of the Astronomical Society of the Pacific](/source/Publications_of_the_Astronomical_Society_of_the_Pacific)*. **132** (1014). [Bibcode](/source/Bibcode_(identifier)):[2020PASP..132h4402Q](https://ui.adsabs.harvard.edu/abs/2020PASP..132h4402Q). [doi](/source/Doi_(identifier)):[10.1088/1538-3873/ab9504](https://doi.org/10.1088%2F1538-3873%2Fab9504).

v t e Exoplanets Planet Definition IAU Planetary science Main topics Exoplanet Exoplanet orbital and physical parameters Methods of detecting exoplanets Planetary system Planet-hosting stars Sizes and types Terrestrial Carbon planet Catastrophically evaporating planet Coreless planet Desert planet Dwarf planet Hycean planet Ice planet Iron planet (Super-Mercury) Lava planet Ocean world Mega-Earth Steam world Sub-Earth Super-Earth Titan-like Venus-like Gaseous Cold Jupiter Eccentric Jupiter Mini-Neptune (Gas dwarf) Helium planet Hot Jupiter Hot Neptune Gas giant Ice giant Neptunian Jupiter analogue Super-Jupiter Super-Neptune Super-puff Ultra-hot Jupiter Ultra-hot Neptune Warm Jupiter Other types Blanet Brown dwarf Chthonian planet Circumbinary planet Circumtriple planet Disrupted planet Double planet Ecumenopolis Eyeball planet Giant planet Mesoplanet Planemo Planet/Brown dwarf boundary Planetesimal Protoplanet Pulsar planet Second generation planet Sub-brown dwarf Sub-Neptune Toroidal planet Ultra-cool dwarf Ultra-short period planet (USP) Formation and evolution Accretion Accretion disk Asteroid belt Circumplanetary disk Circumstellar disc Circumstellar envelope Cosmic dust Debris disk Detached object Disrupted planet Excretion disk Exozodiacal dust Extraterrestrial materials Extraterrestrial sample curation Giant-impact hypothesis Gravitational collapse Hills cloud Internal structure Interplanetary dust cloud Interplanetary medium Interplanetary space Interstellar cloud Interstellar dust Interstellar medium Interstellar space Kuiper belt List of interstellar and circumstellar molecules Merging stars Molecular cloud Nebular hypothesis Oort cloud Outer space Planetary migration Planetary system Planetesimal Planet formation Protoplanetary disk Radial drift Ring system Rubble pile Sample-return mission Scattered disc Star formation Systems Exocomet Interstellar Exomoon Tidally detached Rogue planet Jupiter-mass binary objects Orbits Retrograde Trojan Mean-motion resonances Titius–Bode law Host stars A B Binary star Brown dwarfs F/Yellow-white dwarfs G/Yellow dwarfs Herbig Ae/Be K/Orange dwarfs M/Red dwarfs Pulsar Red giant Subdwarf B Subgiant T Tauri White dwarfs Yellow giants Detection Astrometry Direct imaging list Microlensing list Polarimetry Timing list Radial velocity list Transit method list Transit-timing variation Habitability Astrobiology Astrooceanography Circumstellar habitable zone Cosmic shoreline Earth analog Extraterrestrial liquid water Galactic habitable zone Habitability of binary star systems Habitability of F-type main-sequence star systems Habitability of K-type main-sequence star systems Habitability of natural satellites Habitability of neutron star systems Habitability of red dwarf systems Habitability of yellow dwarf systems Habitable zone for complex life List of potentially habitable exoplanets Tholin Superhabitable planet Catalogues Nearby Habitable Systems Exoplanet Data Explorer Extrasolar Planets Encyclopaedia NASA Exoplanet Archive NASA Star and Exoplanet Database Open Exoplanet Catalogue Lists Exoplanetary systems Multiplanetary systems Circumstellar discs Exoplanets Discoveries Extremes Firsts Nearest Largest Heaviest Terrestrial candidates Kepler 1–500 501–1000 1001–1500 1501–2000 2001–2500 K2 Potentially habitable Proper names Discovered exoplanets by year before 2000 2000–2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 Other Carl Sagan Institute Exoplanet naming convention Exoplanet phase curves Exoplanetary Circumstellar Environments and Disk Explorer Extragalactic planet Extrasolar planets in fiction Geodynamics of terrestrial exoplanets Neptunian desert Nexus for Exoplanet System Science Planets in globular clusters Small planet radius gap Sudarsky's gas giant classification Discoveries of exoplanets Search projects

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Adapted from the Wikipedia article [Ice planet](https://en.wikipedia.org/wiki/Ice_planet) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Ice_planet?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.