Ocean world

For other uses, see Ocean World (disambiguation). Not to be confused with World Ocean. Not to be confused with Waterworld.
Earth's surface is dominated by the ocean, which forms 75% of Earth's surface.

An ocean world, ocean planet or water world is a type of planet that contains a substantial amount of water in the form of oceans, as part of its hydrosphere, either beneath the surface, as subsurface oceans, or on the surface, potentially submerging all dry land.[1][2][3][4] The term ocean world is also used sometimes for astronomical bodies with an ocean composed of a different fluid or thalassogen,[5] such as lava (the case of Io), ammonia (in a eutectic mixture with water, as is likely the case of Titan's inner ocean) or hydrocarbons (like on Titan's surface, which could be the most abundant kind of exosea).[6] The study of extraterrestrial oceans is referred to as planetary oceanography.

Earth is the only astronomical object known to presently have bodies of liquid water on its surface, although subsurface oceans are suspected to exist on Jupiter's moons Europa and Ganymede and Saturn's moons Enceladus and Titan. [7] Several exoplanets have been found with the right conditions to support liquid water.[8] There are also considerable amounts of subsurface water found on Earth, mostly in the form of aquifers.[9] For exoplanets, current technology cannot directly observe liquid surface water, so atmospheric water vapor may be used as a proxy.[10] The characteristics of ocean worlds provide clues to their history and the formation and evolution of the Solar System as a whole. Of additional interest is their potential to originate and host life.

In June 2020, NASA scientists reported that it is likely that exoplanets with oceans are common in the Milky Way galaxy, based on mathematical modeling studies.[11][12]

  1. ^ "Ocean planet definition/meaning". Omnilexica. 1 October 2017. Archived from the original on 2 October 2017. Retrieved 1 October 2017. An ocean planet is a hypothetical type of planet which has a substantial fraction of its mass made of water. The surface on such planets would be completely covered with an ocean of water hundreds of kilometers deep, much deeper than the oceans of Earth.
  2. ^ Adams, E. R.; Seager, S.; Elkins-Tanton, L. (1 February 2008). "Ocean Planet or Thick Atmosphere: On the Mass-Radius Relationship for Solid Exoplanets with Massive Atmospheres". The Astrophysical Journal. 673 (2): 1160–1164. arXiv:0710.4941. Bibcode:2008ApJ...673.1160A. doi:10.1086/524925. S2CID 6676647. A planet with a given mass and radius might have substantial water ice content (a so-called ocean planet), or alternatively a large rocky iron core and some H and/or He.
  3. ^ Nimmo, F.; Pappalardo, R. T. (8 August 2016). "Ocean worlds in the outer solar system" (PDF). Journal of Geophysical Research. 121 (8): 1378. Bibcode:2016JGRE..121.1378N. doi:10.1002/2016JE005081. Retrieved 2017-10-01.
  4. ^ Vance, Steve; Harnmeijer, Jelte; Kimura, Jun; Hussmann, Hauke; Brown, J. Michael (2007). "Hydrothermal Systems in Small Ocean Planets". Astrobiology. 7 (6): 987–1005. Bibcode:2007AsBio...7..987V. doi:10.1089/ast.2007.0075. PMID 18163874.
  5. ^ [Ocean Worlds: The story of seas on Earth and other planets]. By Jan Zalasiewicz and Mark Williams. OUP Oxford, October 23, 2014. ISBN 019165356X, 9780191653568.
  6. ^ F. J. Ballesteros; A. Fernandez-Soto; V. J. Martinez (2019). "Title: Diving into Exoplanets: Are Water Seas the Most Common?". Astrobiology. 19 (5): 642–654. doi:10.1089/ast.2017.1720. hdl:10261/213115. PMID 30789285. S2CID 73498809.
  7. ^ https://science.nasa.gov/solar-system/ocean-worlds/
  8. ^ "Are there oceans on other planets?". National Oceanic and Atmospheric Administration. 6 July 2017. Retrieved 2017-10-03.
  9. ^ "Aquifers and Groundwater | U.S. Geological Survey". www.usgs.gov. Retrieved 2023-05-02.
  10. ^ Cite error: The named reference Seager 2013 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference NASA-20200618 was invoked but never defined (see the help page).
  12. ^ Quick, Lynnae C.; Roberge, Aki; Barr Mlinar, Amy; Hedman, Matthew M. (2020-06-18). "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. 132 (1014): 084402. Bibcode:2020PASP..132h4402Q. doi:10.1088/1538-3873/ab9504. S2CID 219964895.