Geyser

A geyser is a type of hot spring that erupts periodically, ejecting a column of hot water and steam into the air. The name geyser comes from Geysir, the name of an erupting spring at Haukadalur, Iceland; that name, in turn, comes from the verb gjósa, "to gush".

Geysers on Triton

One of the great surprises of the Voyager 2 flyby of Neptune in 1989 was the discovery of geysers on its moon, Triton. Astronomers noticed dark plumes rising to some 8 km above the surface, and depositing material up to 150 km downstream.

Related Topics:
Voyager 2 - Neptune - Triton

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All the geysers observed were located between 40° and 60°S, the part of Triton's surface close to the subsolar point. This indicates that solar heating, although very weak at Triton's great distance from the Sun, probably plays a crucial role. It is thought that the surface of Triton probably consists of a semi-transparent layer of frozen nitrogen, which creates a kind of greenhouse effect, heating the frozen material beneath it until it breaks the surface in an eruption. A temperature increase of just 4 K above the ambient surface temperature of 38 K could drive eruptions to the heights observed.

Related Topics:
Transparent - Nitrogen - Greenhouse effect - K

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Geothermal energy may also be important. Unusually for a major satellite, Triton orbits Neptune in a retrograde orbit—that is, in the opposite direction to Neptune's rotation. This generates tidal forces which are causing Triton's orbit to decay, so that in a few million years time it will collide with Neptune. The tidal forces may also generate heat inside Triton, in the same way as Jupiter's gravity generates tidal forces on Io which drive its extreme volcanic activity.

Related Topics:
Retrograde - Tidal force - Jupiter - Io

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Each eruption of a Triton geyser may last up to a year, and during this time about 0.1 km³ of material may be deposited downwind. Voyager's images of Triton's southern hemisphere show many streaks of dark material laid down by geyser activity.

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