Normally in sun-like planetary systems, there are small rocky planets around the habitable zone or closer and gas giants beyond the frost line. Typically these gas giants later migrate inwards due to a type 2 migration.

And in our solar system, the moons orbiting these giants are engulfed by a deep frozen Ocean, a.k.a. they seem to bear too much water for life. Apart from Jupiter's Io which has a terrestrial surface, maybe due to its high geological activity. I assume that is because water is lighter than metals and silicates. And because of that it tends to move outside.

My goal is to have a gas giant and natural satellites which are ready to be terraformed and then develop their own stable water-based and terrestrial ecosystems due to this process.

I was thinking of the following setup

  • Star: G-type with 1 solar mass
  • Gas giant or cool Brown Dwarf with 10 Jupiter masses, orbiting the star in a semi major axis of 3 AU
  • This gas planet/failed star has multiple moons from 0.6 to 1.5 Earth masses

My Question is then: Could there be a system where the star is still sun-like, but this over-abundance of water is not there, or more towards the outer edge of the solar system? So that a potential human-like civilization arriving and terraforming these moons still can have the land-based way of life they are used to?

  • $\begingroup$ Are you asking "can there be mostly-rocky bodies with only trace water at 3AU?" or "is a super-Jupiter with multiple earth-mass moons at 3AU from a sun-mass star plausible?" or "if such moons existed would they be plausible candidates for terraforming?" Or perhaps just "I want a gas giant with a human-habitable moon. Could such a thing exist in reality, and how?" $\endgroup$
    – g s
    Commented Apr 29 at 7:49
  • $\begingroup$ The first one you mentioned is best for now $\endgroup$
    – Ben
    Commented Apr 29 at 13:52


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