World building idea: Jupiter-sized Earth

[Mercurius]

This is actually an idea I'm playing with for a writing project, but thought the smart folks of ENWorld could offer good advice.

The basic idea--at least relevant to discussion here--is a Jupiter-sized world, but one that is inhabitable by humans.

Some questions:

*What are some basic factors I'd need to consider? Stuff like seasons, weather, climate, yearly and daily cycles, etc.

*Has anyone created a "mega-world" for their RPG?

*Any fiction or non-fiction books that explore this idea? The closest thing I can think of is the SF novel Orbitsville by Bob Shaw, although that's a Dyson Sphere.

*I did find a couple videos on Youtube, but any other resources?

Feel free to share whatever inspires you!

Thanks!

 

[GuyBoy]

Wow....thinking big!

I’m a political historian, not a scientist, so I’ll leave mechanics, seasons, days etc to others, but one thing that strikes me is the question of trade and transport.
Depending on technology levels, trade distances will be so vast that mercantile trades could take a good percentage of somebody’s life (they could take months on our own little globe), so a solution to that, magical or otherwise, would be a priority perhaps?
Communication challenges would also be immense; Prior to the railways and telegaraph, it took around four months for the Tsar’s messages to be relayed on horseback from St Petersburg to Vladivostok. Large empires could be tricky?

You may have found a good basis for Points of Light, with tens of thousands of miles of Howling Wilderness in between.

 

[Mercurius]

Wow....thinking big!

I’m a political historian, not a scientist, so I’ll leave mechanics, seasons, days etc to others, but one thing that strikes me is the question of trade and transport.
Depending on technology levels, trade distances will be so vast that mercantile trades could take a good percentage of somebody’s life (they could take months on our own little globe), so a solution to that, magical or otherwise, would be a priority perhaps?
Communication challenges would also be immense; Prior to the railways and telegaraph, it took around four months for the Tsar’s messages to be relayed on horseback from St Petersburg to Vladivostok. Large empires could be tricky?

You may have found a good basis for Points of Light, with tens of thousands of miles of Howling Wilderness in between.

Part of the appeal is the idea that there could exist entirely separate "worlds" (or continents and island chains) that never interact with anywhere else, except through magic (or technology, if SF). Meaning, you could have literally dozens of unique micro-worlds/regions/continents that develop autonomously. That is, if the native species were Earth-like.

Another thought is a grid of magic portals that only an elite mage order controls, thereby controlling global politics and economics.

 

[Davies]

You might want to read Robert Silverberg's Majipoor stories and novels; while that planet is about ten times the size of Earth instead of Jupiter's eleven times size, it illustrates the concepts you want to explore rather well.

 

[Tun Kai Poh]

This is actually an idea I'm playing with for a writing project, but thought the smart folks of ENWorld could offer good advice.

The basic idea--at least relevant to discussion here--is a Jupiter-sized world, but one that is inhabitable by humans.

Some questions:

*What are some basic factors I'd need to consider? Stuff like seasons, weather, climate, yearly and daily cycles, etc.

*Has anyone created a "mega-world" for their RPG?

*Any fiction or non-fiction books that explore this idea? The closest thing I can think of is the SF novel Orbitsville by Bob Shaw, although that's a Dyson Sphere.

*I did find a couple videos on Youtube, but any other resources?

Feel free to share whatever inspires you!

Thanks!

The Warbirds RPG setting, by Steve and Cait Bergeron of Outrider Studios, has a Jupiter-sized world, but rather than solid, it has different gas layers, as well as floating islands which in the Warbirds timeline were mysteriously displaced from the Carribbean region of 1800AD Earth to this new environment. The default setting takes place centuries later, with skyships and air pirates battling it out over the skies of this region known as Azure.


Further revelations in Warbirds: The Space Age indicate that the humans of 1800 Earth, along with many other sapient species from across the galaxy, were all brought to the same galactic neighbourhood in order to start spacefaring civilizations in the same general vicinity and time, as if some powerful advanced power wanted to see them arise and compete...

 

[TwoSix]

I'm assuming a ton of magic is in play here, correct? Since a rocky planet the size of Jupiter is almost impossible, and would have a crushingly high gravity.

 

[payn]

You'd need to figure out gravity. A planet 11X the size of earth would explode your heart just trying to move. Though, people would be like the hulk if they could actual live there and then visit an Earth size planet!

 

[Jfdlsjfd]

I wouldn't mind about gravity. Things fall because they are heavy and wet, not because they have this attracting mass nonsense. Once it's out of the way (and frankly, you can't have real life physics and human-like population on such a planet), let's focus on the story. Assuming you want a roughly Earth-like environment on the surface, seas would be immense. And the more sea there is, the more storms a ship is susceptible to meet. You could very well have continents totally out of reach of each others by conventional means. When you mention "cut off areas" on the surface, it's a thing to imagine cultures developping separately in isolation, but you can have that on a regular-sized planet (japan vs europe, say). It would be more varied to imagine whole ecosystems cut off for millions of years and having a totally different bestiary. And a few magically-travelling intelligent species. Perhaps reverting the usual setup of varied cultures and a largely invariant, earth-like fauna and flora, and have a few worldwide cultures (who recently managed to acquire continent-hoping magic) and confronted to adapting to extremely varied environment who evolved segregated for millions of years?

 

[Umbran]

Some questions:

*What are some basic factors I'd need to consider? Stuff like seasons, weather, climate, yearly and daily cycles, etc.

So, there's a lot to unpack there. What factors you need to consider depend on how much you care about real reality. In a fantasy work, you can just say, "The planet is friggin' huge, and everything else is exactly the same." and be done with it.

The biggest "science" issue is the planet density. Assume the planet is the size of Jupiter. Assume you want a surface gravity equal to that of Earth. Then the planet has to have about 10% the density of Earth, overall, or roughly 0.5 g/cc. Water is 1 g/cc.

So, you need a rocky world that is less dense than water. That's a hard thing to explain, in normal science.

*Any fiction or non-fiction books that explore this idea? The closest thing I can think of is the SF novel Orbitsville by Bob Shaw, although that's a Dyson Sphere.

Robert Silverberg wrote eight books set on the world of Majipoor, which generally fits the description.

 

[Mallus]

Read Lord Valentine's Castle for inspiration (the first Majipoor novel). It's fantastic.

Maybe the Big World is an ancient super-science construct; a metal shell with dirt & a biosphere over top.