Whenever I see "there is a planet in the habitable zone, but it's a gas giant" I always think gas giants can have rocky moons so it's still a viable candidate for habitability.
Finding a gas giant isn't a downer. I would even go so far as to say a large gas giant in the habitable zone potentially increases the possibilities of a habitable world. Even accounting for radiation belts. The number of moons they can have ups the dice rolls.
Yeah, you'd think that the Avatar movies would have raised awareness about the possibilities of habitable moons (if not Return of the Jedi).
The number of potential moons is a bonus, as is the fact that they wouldn't be tide locked to the star (although it's unclear how much of a problem that is).
It may also up the chances of active geology, which may be important.
@isaackuo Exactly, ice shell moons are probably very common as well. The most common life in the galaxy could very well be subsurface life living in oceans of ice moons undergoing tidal heating. For more Terran centric life it also still stands. A large rocky moon could orbit far away from its gas giant outside of its radiation belt and do just fine with its own magnetic feild. Exo moons give us multiple chances per orbit position instead of a single rocky planet.
I must admit I'm more fascinated by the possibilities of icy moon life than Earth-like planet/moon life. If the biosphere is powered by tidal heating, there might be no ambient light ... no reason to evolve either bioluminescence or photoreceptors ...
So, life forms could be so weird to us, even very different from deep sea life forms.
Hey. I just realized that my impression that there can't generally be a moon of a moon might be based on outdated scientific understanding.
I mean, I'm not sure ... it just feels to me like the kind of thing that scientists might believe in decades past but then improved computer modelling or something disproves it.
The second paragraph of the Wikipedia article indeed suggests it IS possible:
Very cool! I am particularly stunned by Iapetus' equatorial ridge, which I never knew about.
I wonder if it was an inspiration for Kim Stanley Robinson's early work, A Short, Sharp Shock, in which a man with amnesia awakens on a world which consists only of a narrow strip of land around the center of a planet, separating two oceans.
The local people's creation myth was of a snake encircling the world.
Yes, crazy moon Iapetus looks like a cheap rubber ball with a mold line around the equator.
Last I heard the theory was that the ridge was formed by a moon entering Iapetus' Roche limit, being fragmented, and the fragments eventually all landing along the equator
@DenOfEarth@isaackuo@Aaron_DeVries@nyrath Voyager 2 photographed Iapetus from 565,000 miles away in 1981; the equatorial ridge was only discovered by the Cassini orbiter in 2004 (at closest approach Cassini got to within 1000 miles of Iapetus in 2007, with better cameras).
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