I have heard that a moon in our solar system orbiting Saturn possesses geographical features that essentially spit out water and moisture from 'volcanoes' on its surface. The volume of water outputted thus far is such that it comprises a faint ring of Saturn

Would it be possible for a rocky planet orbiting their Sun/gas giant to have the right combination of volcanic activity and low-gravity such that magma thrown up by the volcanoes ends up in orbit of the small planet, cooling over time to form rings?

It seems to have happened with that specific moon of Saturn, with water, and rings formed around Saturn instead of the moon itself? Can it be possible with cooled-down lava?

  • 4
    $\begingroup$ Individual objects shot from the surface will either escape or intersect the surface again very soon they can 't easily go into orbit by themselves. But if a lot of mater goes up and there are collisions, and orbital velocity is not terribly high, then some could end up in orbit. $\endgroup$
    – uhoh
    Commented Aug 19, 2021 at 10:03
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    $\begingroup$ I'd like to point out that "lava" is used when magma (i.e., molten rock under the surface) reaches the surface effusively, where it generally flows quite gently. You probably think of "tephra", i.e., volcanic ash, lapilli and bombs, ejected when magma reaches the surface explosively. On Earth fine tephra (ash) can reach high altitudes (up to 50 km, compared to 1-2 km "only" for lava fountains), so if anything volcanic would reach space on some planetary body, it would be tephra, not lava. $\endgroup$ Commented Aug 19, 2021 at 12:59
  • $\begingroup$ One of moon formation hypothesis is that a large body hit the earth and produced a ring of debris around the earth which eventually formed into the moon. So not a volcano, but kinda sorta similar in that a bunch of stuff shot up and (temporarily) formed a ring. $\endgroup$
    – eps
    Commented Aug 19, 2021 at 20:01

2 Answers 2


This doesn't seem to occur in our solar system. The most volcanic body, Io, does create a trail of gas around its orbit of Jupiter, but has no ringlike structure of its own.

As uhoh notes, orbital dynamics means that if an object is projected from the surface of a planet or moon it will either exceed escape velocity (in which case it goes out into space) or it will travel on an ellipse that must intersect with the starting position (at the surface). It is more or less impossible to put something into orbit with a single push from the surface. Rockets need an initial push up and then a push along to achieve orbit, though these phases are normally merged.

However as uhoh also notes, in principle matter on an escape velocity could interact with other orbiting matter, lose some energy and so enter orbit as a ring. Perhaps a possible scenario is that matter is ejected into a torus of dust around the planet, which is then gathered by the moon into a ring. However this hasn't occurred in our solar system.


It was not observed before. But observations that we have might say that it is possible.

1st - to Io example. Io escape velocity is 2.558 m/s.Still the erupted matter, temperature, and path going through the atmosphere matters. Io's volcanoes: majority, have a temperature of the order of 350-400 K and a speed of emission of gas products of about 500 m/s, an ejection height of up to 100 kilometers; high caldera temperature ones. The higher vent temperatures and pressures generate eruption speeds of up to 1 kilometre per second, reaching heights of between 300 and 500 kilometres. Still ‘raining’ back to surface. 2nd - to cryovolcanoes which are observed within the Solar System, icy moons of, including Europa, Titan, Ganymede, and Miranda.


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