Social, religious and political development in the orbit of a gas giant

[Ford Prefect]

Seeing as I'm at work, I'm going to take a quick break to ask a question. I have had a particular fantasy story idea in my mind for a while now, and was idly thinking about the world on which it's set. I thought that it might be interesting if that world was one of the moons of a gas giant. While this is more a science fiction idea - most spectacularly depicted in James Cameron's Avatar and more recently in the dreamlike sky boxes of Destiny 2 - it's not unusual for fantasy lands to have more than one moon (it's practically a cliché, really).

For the purposes of the question, you should assume that this is a fantastical otherworld. The humans living on this moon at not colonists or descendants of colonists, but rather independently developing humans that are, some adaptations to their environment aside, essentially interchangeable with us. At the time of the story they have reached a similar level of social and technological development to the modern day, or the day after the modern day.

Further, you should assume that while wild, the world is otherwise fairly habitable. It has a functional enough day-night cycle (though the nights are very bright) and while significantly more geologically active and prone to meteor strikes, it's not so harsh that fighting the environment takes up most of everyone's energy. They're just facts of life to be dealt with.

I'm interested in some perspectives on what kinds of beliefs and systems might arise in this kind of planetary arrangement. Some things I've considered:

- The gas giant itself dominates the sky a lot of the time, particularly at night.
- There are other moons in orbit around the gas giant, some of which are visible in the world's sky, and cast visible shadows.
- Brushes with the gas giant's radiation belts cause spectacular auroras.
- Falling stars are a pretty regular occurrence.
- I should probably make a call on whether the world is realistically tidally locked, or somehow rotating.

With the assistance of others I've come to think that the shadows cast on the gas giant would give significant insights even to people observing the sky with the naked eye, and @Peel suggested that a more complicated planetary system would make it clear to people that there are other worlds than these.

I'm interested in any insights people might have on this kind of system, rather than necessarily having to respond to the specific ideas I've been having about this fantasy setting. Have at it!

 

[Michael Lewis]

Are we supposed to consider issues like how such a place sustain any decent amount of plant life (and by extension, a meaningful ecosystem)? That alone could cause problems, but given the admittedly fantastical premises of the question I suspect it's in the "let's sweep it under the rug" category of issues.

 

[Ford Prefect]

Are we supposed to consider issues like how such a place sustain any decent amount of plant life (and by extension, a meaningful ecosystem)? That alone could cause problems, but given the admittedly fantastical premises of the question I suspect it's in the "let's sweep it under the rug" category of issues.

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I don't think it's outrageous that a moon of a gas giant could sustain and earth-like habitable ecosystem - even if it's astronomically unlikely, it would have to happen somewhere in the universe.

You can probably assume that the plant and animal life is pretty hardy.

 

[Jonen C]

Tidally locked or not?

The closer to the giant the more likely to be locked, in which case you always have thw gas giant in the sky, or never.

 

[NothingNow]

I don't think it's outrageous that a moon of a gas giant could sustain and earth-like habitable ecosystem - even if it's astronomically unlikely, it would have to happen somewhere in the universe.

You can probably assume that the plant and animal life is pretty hardy.

Click to shrink...

Most large moons of gas giants are subject to tidal forces severe enough to mean living on one with liquid water would be pretty unpleasant if it's not tidally locked.

These guys are probably not going to like being near the shore at all, just to avoid the twice an orbit tsunami.

 

[LargeHamCollider]

One of the first practical applications of modern astronomy was time keeping. When Galileo and other early modern astronomers made studies on the orbits of gas giants and their moons, they discovered that these systems can act as a universal clock. If your gas giant's have visible moons with regular orbits, your alternate humans can develop similar models, but without the use of telescopes.

So using the moons as a universal clock, humans can calculate longitudes to make accurate charts and maps. If these measurements can be made relatively easily and quickly, many societies could make these discoveries relatively early and independently. If the measurements can be made on board of a ship, alt!Earth's sea faring cultures could expand much further and faster than compared to our Earth's cultures.

This could lead to global culture clashes and expansion happening much earlier compared to our timeline. Imagine the Hellenic Greeks meeting the late Olmecs. Or a Polynesian expansion that covers multiple oceans.

Also Artifexian posted an incredibly detailed video on how a gas giant system, with mathematical formulas and everything. I couldn't find any citation for the video, so you might want to double check if you need to use any of it.

 

[Sandy River DL]

A bit obvious, but the gas giant would play a big role in the religions of the moon's population, likely serving as a chief deity in place of or alongside the sun.

 

[BiopunkOtrera]

Nights would be really bright, because the gas giant is going to be really bright. Working a night shift will be a lot less unpleasant.

 

[Avernus]

A bit obvious, but the gas giant would play a big role in the religions of the moon's population, likely serving as a chief deity in place of or alongside the sun.

Click to shrink...

Especially if it has a really visible, long lasting eye storm like Jupiter. Really good odds there that all sorts of myths and religions hold that the gas giant is a Divine Eye watching the world.

 

[Tasrill]

A bit obvious, but the gas giant would play a big role in the religions of the moon's population, likely serving as a chief deity in place of or alongside the sun.

Click to shrink...

I will note that it would be a more 'on average' kind of thing. After all even on earth you have chief deities that aren't the sun plenty of times. Still no matter what the gas giant is going to be an important part of all mythologies.

 

[Tibby the Cat]

Seeing as I'm at work, I'm going to take a quick break to ask a question. I have had a particular fantasy story idea in my mind for a while now, and was idly thinking about the world on which it's set. I thought that it might be interesting if that world was one of the moons of a gas giant. While this is more a science fiction idea - most spectacularly depicted in James Cameron's Avatar and more recently in the dreamlike sky boxes of Destiny 2 - it's not unusual for fantasy lands to have more than one moon (it's practically a cliché, really).

For the purposes of the question, you should assume that this is a fantastical otherworld. The humans living on this moon at not colonists or descendants of colonists, but rather independently developing humans that are, some adaptations to their environment aside, essentially interchangeable with us. At the time of the story they have reached a similar level of social and technological development to the modern day, or the day after the modern day.

Further, you should assume that while wild, the world is otherwise fairly habitable. It has a functional enough day-night cycle (though the nights are very bright) and while significantly more geologically active and prone to meteor strikes, it's not so harsh that fighting the environment takes up most of everyone's energy. They're just facts of life to be dealt with.

I'm interested in some perspectives on what kinds of beliefs and systems might arise in this kind of planetary arrangement. Some things I've considered:

- The gas giant itself dominates the sky a lot of the time, particularly at night.
- There are other moons in orbit around the gas giant, some of which are visible in the world's sky, and cast visible shadows.
- Brushes with the gas giant's radiation belts cause spectacular auroras.
- Falling stars are a pretty regular occurrence.
- I should probably make a call on whether the world is realistically tidally locked, or somehow rotating.

With the assistance of others I've come to think that the shadows cast on the gas giant would give significant insights even to people observing the sky with the naked eye, and @Peel suggested that a more complicated planetary system would make it clear to people that there are other worlds than these.

I'm interested in any insights people might have on this kind of system, rather than necessarily having to respond to the specific ideas I've been having about this fantasy setting. Have at it!

Click to shrink...

You would see general 20-30 meter tides all throughout the planet if it isn't tidally locked, so basically every port would need to be treated like the Bay of Fundy. You'd see a lot more flat-bottom ships to adapt to this fact resting on the newly exposed seabed. This would make a non-tidally-locked moon very interesting I'd think. Tidal force correlates linearly with the height of tides (from what research I've done, it was several years ago), and drops off at the cube of orbital distance. You would probably want it to not be tidally locked just so you could have those cool effects.

To avoid tidal locking you could have it a bit of a ways farther from the gas giant, so several lightseconds. Days and nights would be longer than on Earth. You can also calculate the area of the sky it takes up pretty easily based on how many times larger its diameter is than the moon, and then dividing that by however many times far away it is from the planet than the earth is from the moon.

You'd probably see monthly eclipses (month being defined by an orbit around the gas giant) and such, if it were not tidally locked.

 

[firefossil]

A bit obvious, but the gas giant would play a big role in the religions of the moon's population, likely serving as a chief deity in place of or alongside the sun.

Click to shrink...

Eh I'd think it'd be more likely to be seen as a place. The Afterlife. The Realm of the Gods. The Fae Lands. It'd also have some substantive effects on scale. Unlike in our case with the sun, it'd be clear that the gas giant is much larger than the moon, and that there are other comparable moons. It'd give a very different sense of scope to inhabitants than what we were used to.

That said while a lot of people are talking about the wondrous sights you do see, what they aren't mentioning is the inverse. Just as light pollution has scoured the stars from our night sky, the gas giant eclipsing the star is basically the only time anyone is going to see much of anything in the night sky besides those two things, plus maybe some of the bigger moons or brightest stars.

You would see general 20-30 meter tides all throughout the planet if it isn't tidally locked

Click to shrink...

Damn that'd mean you'd have tidal zones farther than the eye can see, in some cases the size of small nations. It'd make for interesting cartography, and interesting biology as well.

 

[xa na xa]

That said while a lot of people are talking about the wondrous sights you do see, what they aren't mentioning is the inverse. Just as light pollution has scoured the stars from our night sky, the gas giant eclipsing the star is basically the only time anyone is going to see much of anything in the night sky besides those two things, plus maybe some of the bigger moons or brightest stars.

Click to shrink...

No, you'll see the giant go through phases from full to crescent to new, and during the new phases you can see the night sky unhindered; the contrast in visibility will just be much stronger than between moon phases on Earth (you'll also see a faint red ring or halo as the sunlight diffracts through the giant's atmosphere, this could be considered a major astronomical object in its own right by its inhabitants). Also the gas giant would rise and set due to the planet's rotation and would not always be visible just like our own moon (all this assuming non-tidal lock); conversely, you would also see the giant as waxing and waning full, half, or crescent during day-time at certain times (dusk and dawn particularly), that could be a very impressive sight too.

 

[Vindictus]

Damn that'd mean you'd have tidal zones farther than the eye can see, in some cases the size of small nations. It'd make for interesting cartography, and interesting biology as well.

Click to shrink...

Might make city building interesting as well, depending on how willing the locals are to build 30-meter high restraining walls in the periods between tides and then pump them out (or alternatively just leave a floodgate/drain near the bottom)

While I don't think this would necessarily be advantageous in an early medieval sort of period (aside from the 'Lol just try besieging us mate I hope you brought your boats for when the tide comes in' angle), it might be an effective way to generate electricity in the modern-ish era Ford posits, making hydro-electric plants an effective method of generating a constant flow of electricity for any such sea-forts.

As far as wildlife is concerned... Probably you'd have a lot of amphibious life in that area (which I'm just going to call 'The Shallows') due to the adaptational pressures of, you know, switching between ocean and plains regularly. Maybe some sort of 'amphibious' plants too, somewhere between a tree and seaweed, adapted to do well both submerged and dry?

... Also, what period are we talking about for these tides? Or, rather, how long are the 'days', since that impacts the tides? If we're assuming a 1-to-1 day as compared to earth, then this is all out the window because these areas are horrific regular tsunami zones, but if it's a more gradual rise- Let's say that the planet's 'Day' lasts a month- then suddenly it's much more survivable to live in (if still difficult) because of the more manageable rate of change.

 

[Arcus]

Well, assuming tidal locking, the length of whatever day equivalent our gas giant moon people have would probably be tied to the orbital period instead?

I wonder if they would develop a heliocentric/non-geocentric model of the cosmos sooner, given the opportunity to observe the interactions of the gas giant and the other moons.

 

[Richardson]

Well, assuming tidal locking, the length of whatever day equivalent our gas giant moon people have would probably be tied to the orbital period instead?

I wonder if they would develop a heliocentric/non-geocentric model of the cosmos sooner, given the opportunity to observe the interactions of the gas giant and the other moons.

Click to shrink...

Or center it around their host planet.