I’ve heard of a paper ( mentioned in a similar discussion on another forum ) called “Habitable moons around extrasolar giant planets” in Nature from 1996; this ( PDF ) is the abstract, you’d have to pay to see more apparently.
As chorpler suggests, the nights aren’t necessarily going to be that long. Io, for example, has an orbital period of only 42 hours, so its night will be only 21 hours. (Since it’s tidally locked, the day will be the same length as the orbital period.) The other Galilean satellites have orbital periods of from about 3.5 to 17 Earth days.
I also don’t see the eclipses as being a significant problem, since as dtilque says they will normally be much shorter than the night on any moon.
That’s certainly true for most directors, but this is James Cameron we’re talking about here. He most definitely cares about the science. For example,
For those of you with time to spare…papers from arXiv.org on Habitable moons
Yes, I remember that story. That was my first thought too, a moon will be tidally locked to the planet and the planet will become a perpetually stationary skiy object - location dependent.
SPOILER They ran across a stranded (earthman?) alien who had spent decades trying to assemble enough mercury to repair his spaceship shuttlecraft in this primitive culture. “Drake” destroyed the man’s current stash of mercury because he thought that exploration was the greatest adventure; to have some magically advanced civilization come and hand the world to you would take all the romance and adventure out of it.
I’m sure I have that story in the books buried in my basement. Someday…
The other issue is - the theory why we have gas giants and terrestrial planets - the solar radiation close in to the sun would “boil off” the lighter elements over the eons. That is why hydrogen and helium dominate on the gas giants, but unless chemically bound are minimal on terrestrial rocky planets. Even water on Mars, the theory is that it has boiled off as solar radiation dissocites water molecules and pushes away the lighter hydrogen. The oygen has reacted with carbon etc.
SO a giant planet close in would likely not retain much light-gas atmoshpere, would still be a rocky planet. Who knows?
What about tides? Earth experiences significant tides from a little moon 1/6 our mass. What would they be like if we had a planey the size of Jupiter or Saturn in our sky?
Solar radiation would prevent a gas giant from forming near the star. The close-orbit giants that have been discovered must have formed farther out and then migrated in through “friction” with other mass in the star system. By then they had enough mass to hold on to their hydrogen even as they got hotter.
We do. While it is theorizedsome close giants will be reduced to a rocky core, we are reasonably certain othershaven’t yet
Yes. I was thinking of Ganymede with its ~86 hour night when I wrote that.
Tidal forces is one reason why Io is so active volcanically and Europa may have liquid water underneath that smooth layer of ice. So…tides would certain play a big role in the development of a theoretical habitable moon.
Just a qualification: If a moon is tidal locked to it’s primary then there are no tides, or rather the tide is fixed in one position. The reason Io and Europa experience tidal heating is because they’re part of an orbital resonance between Jupiter’s moons, so the tidal forces they experience are the result of each other’s gravity. If our hypothetical Earthlike moon had no near neighbors other than it’s primary or small moonlets of negligable mass, it would experience no tidal heating. If there were other big moons orbiting in resonance with it, then yes substantial heating.