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I am continuing my research and work on my scenario which involves several moons surrounding a gas giant.

The satellite in question has 0.6 earth masses, an atmosphere with a decent greenhouse effect more potent than on earth and a semi major axis of about 900000 Km. The primary Planet possesses 12 Jupiter masses, and a semi major axis of about 2 and a half astronomical units related to its star.

Also the moon receives about 15% the sunlight that earth gets and a lunar orbit takes about 40 hours.

Being that massive, the Planet releases heat due to the Kelvin-Helmholtz-Process and other effects, such as tidal heating. This infrared-spectrum energy is caused by the giant planet slowly contracting under its own gravity, converting potential energy into thermal energy.

Due to a calculation I found online, the moon will actually receive much more infrared energy from the planet than from its star, essentially making this gas giant the moons primary source of heat.

So my question is: Due to the moon being tidally locked to this enormous heat source, would that turn the satellite into an "eyeball Moon", where the side facing the primary would look drastically different compared to the cooler side that does not benefit from this energy? Or would frequent eclipses, the atmosphere and its winds partially even out the differences?

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    $\begingroup$ Would I be correct in thinking that the Kelvin-Helmholtz-Process produces an oscillating effect, with a period of a few hundreds or thousands of years or so? $\endgroup$
    – Escaped dental patient.
    Commented Jul 24 at 15:50
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    $\begingroup$ As far as i know, it is not oscillating, but constant. $\endgroup$
    – Ben
    Commented Jul 24 at 15:54
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    $\begingroup$ Maybe, Maybe not. We'll need a few more details to be able to give a good answer: What is the composition of the planet, what is the density and composition of the atmosphere, what temperature ranges do the light/dark sides have, and what kind of life forms if any are on the moon? $\endgroup$
    – Nosajimiki
    Commented Jul 24 at 16:39
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    $\begingroup$ There are too many assumptions here. What are the radii of the moon and planet? What's the rotational period of the planet? What's the chemical composition of the planetary gasses or, better yet, how well does the atmosphere retain heat? But (and I'm being honest here), why does all this matter? You know of a real-world effect that can be used to rationalize what can happen on your moon. Asking us if science forces a condition isn't worldbuilding. Asking if the effect can rationalize a condition you've already decided on is worldbuilding. $\endgroup$
    – JBH
    Commented Jul 24 at 17:58

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There is a crucial detail that makes your worries pointless:

The satellite in question has [...] an atmosphere with a decent greenhouse effect more potent than on earth

and

the Planet releases heat due to the Kelvin-Helmholtz-Process

Greenhouse gases work by reflecting back IR radiation emitted by the planet surface toward outer space, and therefore increasing the temperature of the atmosphere.

But in your case the IR radiation is coming from outer space (the Planet...) to the surface, and the greenhouse gases will reflect it back, therefore not making it warm up the planet surface.

Additionally, the moon will get tidal heating only if it is not tidally locked, because that's the only way to get heat generated by the moving strained region.

As a consequence, you can exclude an eyeball moon from your scenario.

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  • $\begingroup$ Thank you. Yes the point with the infrared radiation being reflected back makes sense to me. Regarding the tidal heating. I think that the perfect sphere or circle does not exist in nature, hence why there is after all, still a minor degree of excentricity in my moons orbit. Just like Io's interaction with Jupiter, (Excentricity of 0.0041, close enough to 0 for me) I imagine the moon in my example experiencing a similar effect like Jupiter's Galilean Moon. $\endgroup$
    – Ben
    Commented Jul 25 at 6:29

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