Animations of Lumar's 12 moons

[+Oltux72]

37 minutes ago, kelianmao said:

Also, for stability, you must consider perturbations with more than just opposing moons;

Absolutely, yes

37 minutes ago, kelianmao said:

 theres an entire 3d structure. For example in 2d, if:

     C
     |
A -- X -- B
     |
     D

gets perturbed to 

     C
     |
 A - X --- B
     |
     D

 

In that example you are using a force that applies to C, X and D, but not to A and B. What kind of force is that? What moves C and D along with X?

37 minutes ago, kelianmao said:

Yes, A is now closer to planet X. However, A is now also closer to moons C and D, meaning it gets repelled away (from the planet X), while B is now further from C and D so it gets less repelled from X. So long as this repulsion is stronger than the increase in gravity, then this is a restoring force, and the system is stable.

 

If you restrict yourself to perturbing single objects, I can see that for A, B, C and D as they are subject to two kinds of forces. But what does it for X?

37 minutes ago, kelianmao said:

The angular momentum of the orbits should also work to keep the orbital radius higher. If the equilibrium is stable, any perturbations are quickly dampened out, and the orbits stay circular, never becoming eccentric enough to affect the appearance of the moons in the sky.

By what mechanism?

[The Cap'n]

What about this:

All 13 celestial bodies have cores of the same material and "charge" (i.e. magnetic, atomic force, magical, aether, investiture, etc.) that repels similar substances (think electrons). Now add in gravity and the planet and moons are all attracted to each other as well, but moreso to the much larger planet. Once they reach a distance where the gravitational attraction force equals the magical repelling force, they should all settle into the aforementioned geometric shape. Maybe like how atoms and molecules can form a crystal given the right conditions.   Add in some spin (or not, maybe the star revolves around the planet/moon structure) and the whole thing could plausibly keep its crystalline formation, more or less. To establish a geosynchronous "orbit" all you need is enough time and the planet should eventually converge in a tidally locked state with its moons.

As for the rock and spores, they aren't made of the same substance as the planetary cores and therefore the spores from the 12 "moons" are ultimately attracted to the planet. The moons are close enough to the planet that the gravitational forces attract the nearest spores, while the strong repelling force of the cores keeps the moons just off the surface. 

Plausible? Barely.  But who knows what's possible in a fantasy genre? 

[alder24]

6 hours ago, The Cap'n said:

What about this:

All 13 celestial bodies have cores of the same material and "charge" (i.e. magnetic, atomic force, magical, aether, investiture, etc.) that repels similar substances (think electrons). Now add in gravity and the planet and moons are all attracted to each other as well, but moreso to the much larger planet. Once they reach a distance where the gravitational attraction force equals the magical repelling force, they should all settle into the aforementioned geometric shape. Maybe like how atoms and molecules can form a crystal given the right conditions.   Add in some spin (or not, maybe the star revolves around the planet/moon structure) and the whole thing could plausibly keep its crystalline formation, more or less. To establish a geosynchronous "orbit" all you need is enough time and the planet should eventually converge in a tidally locked state with its moons.

As for the rock and spores, they aren't made of the same substance as the planetary cores and therefore the spores from the 12 "moons" are ultimately attracted to the planet. The moons are close enough to the planet that the gravitational forces attract the nearest spores, while the strong repelling force of the cores keeps the moons just off the surface. 

Plausible? Barely.  But who knows what's possible in a fantasy genre? 

I don't think this would work. This would require a really strong magnetic field, which would be detectable form Lumar, and this would mess Lumar quite a lot. But there is something that is known as Roche limit, which specify the closest orbit around a planet that a moon can orbit, without being ripped to pieces by tidal force of planet's gravity. Lumar's moon, taking 1/3 of the sky, are far below this limit. 

We just need to accept this is magical world and it doesn't work with our physics

TotES spoiler WoBs about moons:

Spoiler

Lews Therin Telescope

Are the aethers the moons? Or just on the moons?

Brandon Sanderson

On the moons, good question. They are on the moons. The moons are not 100% aether.

https://wob.coppermind.net/events/515/#e16143

 

 

 

Spoiler

Some Anonymous

Back when Tress was first announced, you said that you were imagining the moons and seas as being arranged like the faces of a d12 die. Did the "scientists" who you asked about this ever figure out a way to make this work? Or are the moons something we just have to accept under the rule of cool?

Brandon Sanderson

The moons on Lumar cannot exist without magical intervention. They simply can't. And I'm okay with that; I'm okay, like I said, with some of these planets... We're gonna do other things in the Cosmere that just cannot exist without magical intervention, because otherwise I'd might as well be writing a straight hard science fiction series. And there are lots of great straight hard science fiction series out there that try to extrapolate what things would actually be like. With me, I am trying to create a really interesting environment you haven't seen before, and then ask what that does to the people, realistically, who live there, if that makes sense.

I do treat it seriously. This is canon; those moons are there. But how are the moons there? Cosmereological phenomenon that is impossible in our universe.

Some Anonymous

How high up are the moons away from the planet? Closer to hundreds of miles, like the ISS? Tens of thousands of miles, geosynchronous orbits? If you have that thought out?

Brandon Sanderson

We have discussed it, and I think I'm gonna RAFO it for now. I will say: my current impression is, definitely not as close as the ISS. But not so far, like... One of my inspirations, if you didn't pick up on it already, is obviously Anne McAffrey's Dragonriders of Pern books. Which, if you haven't read those, there are two planets that pass very close to each other, and when they do, dangerous environmental hazards pass from one planet to the other, risking extinction on the habited planet. And I've always loved that setup. And this is a little bit inspired by that. And I don't know how far apart those are, but I'm gonna say: I think it's further than the ISS. But who knows?

https://wob.coppermind.net/events/515/#e16135

 

 

 

 

 

[Argenti]

9 hours ago, alder24 said:

We just need to accept this is magical world and it doesn't work with our physics

 

Yea, sometimes theory-crafting reaches a dead end and you just have to wait until Brandon wants to explain *Cough* F-Iron *Cough*.