All About Space

What are cryovolcan­oes?

- Dr Lynnae C. Quick is an ocean worlds planetary scientist at Goddard Space Flight Center, Maryland

Volcanism, as it is most commonly known, involves the eruption of hot, molten rock or ash. However, numerous worlds in our Solar System exhibit icy volcanism, or cryovolcan­ism, during which cryogenic mixtures – for example a briny slush, ammonia-water slurries or a mélange of icy particles and water vapour – are erupted instead of molten rock.

In addition to shaping the surfaces of several moons in the outer Solar System, cryovolcan­ism has also played a role in sculpting the surfaces of dwarf planets Ceres and Pluto. Just as Earth’s volcanoes are produced by the eruption and gradual build up of lava and ash, cryovolcan­oes are produced in much the same way by the eruption of icy lava, or cryolava.

Dormant cryovolcan­oes such as Ahuna Mons and Wright Mons have been imaged on Ceres and Pluto by NASA’s Dawn and New Horizons spacecraft respective­ly. A subset of domes on Jupiter’s moon Europa may also be small cryovolcan­oes.

At present, active cryovolcan­ism in our Solar System takes the form of the eruption of geyserlike plumes on the moons of Jupiter, Saturn and Neptune. NASA’s Voyager 2 and Cassini spacecraft imaged geyser-like eruptions in the south polar regions of Neptune’s moon Triton and Saturn’s moon Enceladus respective­ly, while reanalysis of data from the Galileo spacecraft and observatio­ns by the Hubble Space Telescope and Keck Observator­y reveal possible detections of geyser-like plumes on Jupiter’s moon Europa. In addition, Triton, Europa and Titan show evidence of recently emplaced cryolava flows, suggesting that cryovolcan­ism manifests in a variety of ways on their surfaces.

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Voyager 2 saw geyser-like eruptions on Neptune’s moon Triton
Below: Voyager 2 saw geyser-like eruptions on Neptune’s moon Triton
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