Dione’s global geology

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Cool image time! The picture of Saturn’s moon Dione, taken by Cassini in April 2015 and reduced in size to show here, shows a range of global tectonic geological features. The impact craters we of course understand, but the white linear features are more puzzling. They are probably related to a heating and cooling process, but the full nature of that process is at present not fully understood. Tidal effects and the planet’s cooling over time both contributed, but to what extent is not yet known. Add on top of that the violent effect of impact and the process gets even more complicated. Moreover, do the linear features suggest present geological activity, or are they evidence of past events? Your guess is as good as mine.


  • Localfluff

    Dione is one of the Saturn moons which are thought to have been formed recently, just 100 million years ago (2-3% of the age of the Solar System). This deduced from the orbital mechanics of the moon system.

    As material from the rings move beyond the Roche limit, they are able to accrete to a moon. Tidal interaction with the rings makes the moon move outwards, until it gets trapped by already existing moons out there. Dione should be about as old as the Rocky Mountains. Still under construction.

  • Perhaps the crust is water ice that is covered by a darker layer of dust from the rings. Tidal forces would cause cracks exposing the underlying lighter colored material?

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