Habitable planets outside the 'Zone'

[gchuck]

I'm mainly talking about the moons of gas giants.
If a GG is outside the 'habitable' zone of a system, maybe one orbit, would the GG in question be putting out enough radiation to artificially heat said moon enough to support life?
Curious

 

[GypsyComet]

Real Physics (TM) says "sort of, but". The Jovian moon of Io is the best example here. While not heated by radiant energy from Jupiter, Io is heated by the gravity gradient enough to be consumingly volcanic. It is also so close that the higher energy radiation that results from the interaction between Jupiter's magnetic field and the solar wind is too powerful to allow life.

But you would be warm while you cooked.

Space Opera Physics (TM) says "sometimes, when it suits". A moon might be internally heated by just enough, or be big enough to still have its molten core while farther out, and have a thick atmosphere that won't escape to space readily and keeps temperatures well above what the solar radiation would provide. Is that air going to be breathable? "sometimes, when it suits".

 

[shaunhilburn]

I'm mainly talking about the moons of gas giants.
If a GG is outside the 'habitable' zone of a system, maybe one orbit, would the GG in question be putting out enough radiation to artificially heat said moon enough to support life?
Curious

For a moon to be warmed by radiant heat, the GG would have to be hot enough to be luminous; around 1,000 K or so.

Perhaps if it were a massive GG and still hot with remnant heat of accretion. I once saw a research paper showing cooling curves for sub-stellar brown dwarfs and massive jovian planets. According to calculations, the more massive ones take less than two billion years to cool from 2,000 K to 700 K (sub-luminous).

 

[BRJN]

I've seen the suggestion that an icy moon just a bit too far away from its sun might have a thin ice crust that could be easily punctured, so you could build on any rocky terrain -or "on a continental shelf" (if any) and go from vacuum atmosphere to underwater in a short distance. In places, the ice might be thin enough to let light through to the water underneath, hence algae and an ecosystem. But even though the world is big, the interesting real estate is a small percentage.

 

[GypsyComet]

But even though the world is big, the interesting real estate is a small percentage.

On the surface, anyway. Once a certain TL is attained, that cold, green, dark ocean becomes "the world".