Astronomy and Space

List of ocean worlds in the Solar System

This is a list of ocean worlds in the Solar System, planets or satellites known or suspected to harbor substantial volumes of liquid water, either as subsurface oceans beneath ice shells or, in the case of Io, a global magma ocean. The existence of such oceans is inferred through a range of methods, including spacecraft measurements of induced magnetic fields, tidal Love numbers, libration amplitudes, surface geology, and isotopic geochemistry. As of 2026, three worlds have strong or confirmed evidence of present-day global oceans: Enceladus, where the Cassini spacecraft directly sampled water-ice plumes erupting from a tidally heated interior; Europa, whose Galileo-detected induced magnetic field implies a conductive saltwater layer; and Ganymede, where Hubble Space Telescope observations of auroral oscillations point to an ocean that may exceed the volume of Earth's oceans. Callisto and Pluto are considered probable ocean worlds, while the status of Titan—long thought to host a global water–ammonia ocean—was called into question by a 2025 reanalysis of Cassini tidal data that favors a slushy interior with localized liquid pockets rather than a continuous ocean. Beyond these, a growing number of icy moons, dwarf planets, and trans-Neptunian objects are considered candidates on the basis of interior modeling, spacecraft gravity data, or recent James Webb Space Telescope observations of surface chemistry indicative of geothermal activity. Several bodies, including Charon, Rhea, and Tethys, may have possessed oceans in the past that have since frozen. NASA's Ocean Worlds Exploration Program, established in 2016, coordinates exploration of these targets, with Europa Clipper (launched 2024), JUICE (launched 2023), and Dragonfly (planned launch in 2028) representing the next generation of dedicated missions.

Also on this shelf

See also

• ▸G. Madhavan Nair
• ▸Darmstadt Madonna
• ▸Delta-v budget

Uncatalogued shelf

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