CWBP 2 : Determining the genre and era

[Falconius]

I'm still confused how life would be without tides. Do moons have moons sometimes? I though I saw somewhere that that is a possibility, or I could be making it up... Is it possible to have such a moon that is not tidally locked? Or does the physics always eventually stabilize it that way?

[modernhamlet]

In generally, I don't think the physics allow a moon to have a moon. The gravity of the planet would almost certainly win out in a tug of war.

Digging a bit more, my point about a tidally locked moon not having regular (oceanic) tides wasn't correct. Only if the orbit is circular will there be no tides. Any moon, tidally locked or not, that has an elliptical orbit would experience tides due to the difference in gravitational pull at different distances from the planet.

Of all the peculiarities of tidally locked moons, I believe the one that presents the most difficulty with respect to it being a "normal" (earth-like) planet, is the length of day. Assuming the moon orbits along a different plane than the planetary orbit around the sun (a very reasonable assumption/possibility), then you don't have to worry about it being "in the dark" any more than is thematically interesting. But you DO have to deal with the fact that the day/night cycle is likely to take between 2 and 20+ earth days.

Now if you're allowing magic, particularly planetary magic of the type previously proposed to replace/enhance the magnetosphere, then there's no reason you couldn't hand wave the physics in this one case and declare that the planet orbits quite close to the planet and only has say... a 28 hour day. Happy/interesting side effect: the planet would be frickin' HUGE in the nighttime (and probably daytime!) sky...

[modernhamlet]

Since this is complex (and I have a few extra minutes), I'll summarize how the experience of living on a tidally locked moon would differ from life on a comparable independent planet:
1. For half the planet, there's a big ol' planet in your night sky! And possibly your daytime sky too... The other half of the planet would have no idea about the planet until they sailed/walked to the planet side (or got visitors).
2. Because of the reflected radiation from the planet, plant growth rates (assuming photosynthesis) on the planet side would probably be greater than the outward side. This would make a strong case for strongly different evolutionary paths not just for plants, but for the animals that consume them all the way up to sentients.
3. There will be a lot more volcanoes, geysers, deep sea vents, and other geothermal activity. Because geothermal energy represents a higher proportion of the total energy available to the world, it is more likely to be harnessed by lifeforms of all sorts, from bacteria to advanced civilizations.
4. Because of #3, you're probably a bit further out in the star's habitability zone than a comparably temperate independent planet would be, meaning the cultural relationship between the star and the planet might shift toward the planet.
5. Aurora are frequent and spectacular.
6. Depending on the orbit, there would be at least significantly longer and more frequent eclipses.

So yeah, I guess my take is that if we can resolve the day length problem, this could be great. The opportunities to leverage these differences to build unique and interesting geographies, ecologies, and cultures are many, but the baseline normality of the world is maintained.

[Azélor]

about moons :

Yes it's possible for a moon to have its own moon but it means that the main moon should be far from the planet and her other moons. The secondary moon would have to be much smaller and orbit very close. Otherwise, the planet will simply garb it. If Ganymede was not tide locked and orbited much farther from Jupiter, she could have a small moon. In fact Jupiter's moons are so close to each other that there is an attraction effect between them. But their orbits are stable for some reason.

Hey, a day on Titan would last for 383 hours, so no more: I don't have enough of 24 hours in a day to do all my stuff! Now you have 383!

If it's a problem, the day length could be shorter if the moon was not tide locked as the planet has her own rotation. In fact, I think this is another problem: having no rotation. You see, according to the climate cookbook, if a planet spins faster you have more prevailing winds. But what happens if the planet does not spin at all?

[modernhamlet]

A tidally locked moon still rotates, it just rotates in resonance with it's orbit around the planet. So as long as the day isn't really long (10+ days), you should still get a 3 cell atmospheric structure. At least in theory.

The other major atmospheric drivers are the temperature differential between the night/dark sides and between the equator/poles. Those would still apply as well.

That said, I'm sure it's more complicated than that. This is definitely something I'll try to look into further...

[Azélor]

A while ago, I bought a physic simulation software called Universe sandbox on steam. And apparently the rotation of the Moon around the Earth could be as short as 10 hours or so. She is at 23 600 km from Earth. Normally it's around 400 000 km.


The Earth can orbit Jupiter in 24 hours but would be tide locked for sure. Now there is something I don't understand with the simulator. For the Earth to make one revolution around Jupiter in 24 hours, she need to be at
290 000 km but 40 000 km for the moon to orbit around the Earth in 24 hours. That is a big difference.

[deanrusco]

IMHO, just aswe have not mastered Dark Matter and Energy, the Magic Element could have some influence on keeping a moon orbiting a moon depending on the concentrations of elements in each of the 3 bodies.

This can also be used to "hand wave" numerous other questions and aberrations.

The effects of geothermal energy and solar storms on plant growth, social developments, and warfare questions don't need to be quantified to a rigid scale since it was vastly different in our world and wasn't heald to a rigid scale; the rainforests should've done more?

IMHO that is. Thank you.

[deanrusco]

software question: FT3..the two displays, climate and altitude show in solid bandsof color...is there a script or alteration that will alter altitude to display in thin lines over the bands of climate colors?

thank you

[Azélor]

To recap, here's my view on the setting so far

mid fantasy:

Different races (human, elf, dwarf, orcs, goblin ...) . I think better to keep exotic races apart Example for Dungeon and dragon races: no asimar, genasi or tiefeling... It’s not really a cosmopolitan world where you can find mostly all existing races living peacefully in the same place. The number of races is rather limited and racism exists. Most nations tend to form around 1 race mostly. Minorities exist but multiracial states are rare.

Presence of monsters and creatures: dragon, troll, griffon, ent... but they are not a part of civilized nations. I mean, you don't have an army that uses dragon as they mount for example. Monsters are known to roam the world, but there is a sense of danger and mystery about them.

About planes of existence (again I'm using dnd terms so I’m sorry I you haven't played it) others planes exist but most of the stuff happens in this world. Links with other worlds are rare and usually don't have much impact on the world.

Mid magic:

Not everyone can do magic, only a relatively small portion can. Some are born with this special talent while others have to study years just to master some basic spells but with enough work and practice they can achieve wonders. Middle class people can generally have access to some magic to do simple things or repetitive tasks but most people cannot even afford such things.

Magic in the world affect it in some minor way but is influence should be limited.

Magical creature and items exist but as said before, mortals usually can't tame them. Magical items and services can be bought in a city large enough for those who can afford it. Mages can live a wealthy life by selling their services.

Views about magic vary according to the local customs. Some people may be friendlier to magical users than other. Some may even perceive magic as an incarnation of the devil or something evil.

Things like resurrection are either impossible or really uncommon and usually cause some trauma. It's is not considered a normal practice, some state may even ban the practice.

People usually travel normally like they would have done in the Middle Ages. Some rich trading companies might have mages or device to help them but the cost is often prohibitive. Teleportation should not be something common.

Technology: Here, I see two choices: (or it could be another era too)

High middle Ages:
High Middle Ages - Wikipedia, the free encyclopedia

Late middle ages:
Late Middle Ages - Wikipedia, the free encyclopedia
It could be a late middle age without the diseases.

If I just look at the technology, I think I prefer the high middle age. But since it’s a fiction world, technology could be different. Some countries will be more advanced than others and some countries might posses technologies that did not exists at that time. Europeans could already posses the Chinese and Arabian technologies.

About the world: (mostly astrophysics)

I think it’s better to keep that part simple to avoid confusion. Yes it might be cool but think about how confusing it would be to role-play in such a world. Seasons and day length are different... So I think we could have something different as long as it does not affect the world too much. Having two moons with a very small and faint one or a binary star system with a second star orbiting at billions of kilometres of the planet... would have a visual impact but that’s pretty much all. The star is far enough so it does not heat the planet but it could be seen as a really brilliant object in the sky, even during the day maybe.

[modernhamlet]

If there's nothing different about this world, what's the hook? If the project is just to divvy up a map and come up with a sub-map and cultural/historical write-up for a mid-tech/mid-magic realm within it that may or may not relate to its neighbors, that doesn't seem very cooperative to me. It seems like folks are hoping to set up generic sandbox that allows dozens of people to contribute their own puzzle piece. Based my reading about the last project and the numbers/level of interest in the current project, I don't know if that's the best approach. Maybe I'm just looking for something different than others are though.