Qualified for "How Is That Even Possible!?" or "What Has Science Done?!"?
I just... I... I do not know to comment on that.
This is a planetary system I designed for some of my OCs, human-animal hybrids genetically engineered in the far future as offshoots of humanity more in tune with nature. Rather than terraforming an existing world, they flat-out built their own; one of the planet-building design teams made this one on a dare ages ago. :P
The planet is called Centorus. And yep, the populace does include centaurs. :)
Looks like any old Square RPG, where the world map loops on every border.
In some of the Civilization games, they even refer to world maps that loop North-to-South as well as East-to-West as "donut world" or "torus world".
Of course, this would make a world map be much "wider" than it is "tall", and the closer the map is to a square/"thicker" the torus is, the more distortion there would still be on the inner side. (The innermost latitudinal band ("the poles") is a smaller circle than the outermost band ("the equator").)
That said, it begs the question why the innermost band isn't a ring of ice since it basically seems to be perpetually stuck in the shadow of the other side of the world, while the outermost band would probably be heat-blasted desert if we were to presume the oblique angle of light were to have Earth-like "temperate" temperature regions, since the difference between different latitudes would be pretty extreme compared to anything but a tidal-locked planets. Even if it were spinning like a flipped coin rather than a frisbee, the outer side of the ring would receive vastly more sunlight than the innermost ring, with it's constant "planetary eclipses" every noon.
@NWSiaCB - yes, as it should be quite clear, this is not a square map, it's much wider than it is tall. And of course, tori are only ever really truly "flat" (same curvature everywhere) if they are 4-dimensional; by embedding a torus into 3 dimensions, it becomes bent, such that the inner equator is smaller than the outer equator. Ahhh, that brings back memories of my Topology classes... xD
Yes, some games do quite blatantly refer to doughnut worlds or torus worlds, but I think most just weren't programmed very well but were meant to try to simulate spherical planets.
As to the question of how this planet would spin...I did initially think that having it spin like a hula hoop (or a Frisbee, as you say) would suffice, since that would give areas on the inner equator daylight for half a rotation, but that wouldn't be enough. There'd still be places that would be dark for half a year straight, and light for the other half, without break. Even assuming that the torus is inclined to the plane of its orbit, that still wouldn't be enough.
I think that, as well as spinning like a Frisbee (and inclined to its orbital plane), the rotational axis would also need to precess in quite a large circle (probably at least once per year) so that everywhere is getting light. Days and nights would be extremely irregular in length, especially for the hole-ward side, but everywhere should be lit and reasonably warm.
@NWSiaCB - yes, as it should be quite clear, this is not a square map, it's much wider than it is tall. And of course, tori are only ever really truly "flat" (same curvature everywhere) if they are 4-dimensional; by embedding a torus into 3 dimensions, it becomes bent, such that the inner equator is smaller than the outer equator. Ahhh, that brings back memories of my Topology classes... xD
Yes, some games do quite blatantly refer to doughnut worlds or torus worlds, but I think most just weren't programmed very well but were meant to try to simulate spherical planets.
I never understood why those games wouldn't just make it so going off the "north" end of the map wouldn't send you half the map to the east/west, then make you face south. It still would have an unrealistically square map, but it would at least attempt to simulate a sphere.
(And I have seen some boardgames like Battletech's large-scale conflict spinoff game try to simualte a globe with a map that basically is a dodecahedron laid flat.)
Yet_One_More_Idiot said:
As to the question of how this planet would spin...I did initially think that having it spin like a hula hoop (or a Frisbee, as you say) would suffice, since that would give areas on the inner equator daylight for half a rotation, but that wouldn't be enough. There'd still be places that would be dark for half a year straight, and light for the other half, without break. Even assuming that the torus is inclined to the plane of its orbit, that still wouldn't be enough.
I think that, as well as spinning like a Frisbee (and inclined to its orbital plane), the rotational axis would also need to precess in quite a large circle (probably at least once per year) so that everywhere is getting light. Days and nights would be extremely irregular in length, especially for the hole-ward side, but everywhere should be lit and reasonably warm.
Speaking in terms of physics, a "hula-hoop"/"frisbee" spin would likely be necessary, since I think that would be the only way to keep the torus from collapsing in on itself. (Kind of like the rings of Saturn.) There could be spin in both directions, but without that "hula-hoop"/"frisbee" spin to create centripetal force, the planet would collapse.
Having both types of spin would mean the "rimward" side ("equator") would still get regular-length days all year long, although the "centerward" side ("poles"/"hole-ward") would have two "seasons" of darkness/"eclipse" in the year.
It's also worth noting, however, that it's not just day length that causes parts of a globe to be warmer or colder, but the angle of the sun. Even during the arctic summer, a 24-hour sun doesn't make it as warm as the tropics because it's at such an oblique angle to the sun that it's only getting a fraction of the sun's rays the tropics get even during the tropical "winter".
Hence, the inner centerward band would basically never have direct sun because that would only line up during an "eclipse" period when the opposite side's rimward side would be getting full sun. (Granted, I'm basing all of this on an assumed single point of light - if the binary stars were shifted far enough apart to spread solar rays from a divergent enough angle, there might also be phases of the "solar years" where the suns could have line of sight on the inner band of the torus... but getting close enough for that to take place would likely put the torus world FAR too close to the stars' orbits for the torus to be habitable.) The best it would get would be a summer that has sun from
Also-also, if you have spin in two directions, that basically means you have two different types of "days" to work with. That is to say, the longitudinal spin ("hula-hoop"/"frisbee") would likely need to be pretty fast, and probably faster than the latitudinal ("coin flip") spin. Realistically, they wouldn't necessarily line up, (but what about this setup is realistic?) but you might have a "week" be a latitudinal spin, while a "day" be a longitudinal spin on this world... and there could be any arbitrary number of days in a week.
Regardless, though, the rimward side of the torus is going to be getting a lot more sun on average over the course of the year than even the "temperate band" of the "north" or "south" bands of the torus, and vastly more than the centerward side.
In fact, depending on how you want to angle it, the rimward edge might be a blasted desert with a fairly temperate "north" and "south" band, or have a rimward band that is temperate with cold and forbidding tundras that only rarely see light enough to host any life at all in certain times of year. Depending on what kind of fantasy you want to tell, either one would be an interesting concept. (If characters need to get to a certain location in the centerward side and can only survive the trip during the half of a "week" during the "summer" when it will actually get sun, then you have a built-in race against the clock that highlights the strangeness of the topography.)
Y'know, I think we may be thinking about this a bit too much...? ;)
It's not too much if it's enjoyable to talk about. Besides, this isn't my first conversation about irregularly-shaped planets.
Whether you actually use it in your writing is up to you, of course, but I've always enjoyed some of the more fantastical worldbuilding types of sci-fin and fantasy. (... And why make a point of having a torus world if you're not going to do something interesting with the world building?)
It's not too much if it's enjoyable to talk about. Besides, this isn't my first conversation about irregularly-shaped planets.
Whether you actually use it in your writing is up to you, of course, but I've always enjoyed some of the more fantastical worldbuilding types of sci-fin and fantasy. (... And why make a point of having a torus world if you're not going to do something interesting with the world building?)
Honestly, I'm a bit of a lazy world-builder. I'll build a world, but never really think too hard about the details of that world. Or get bored and wander off for a while and then come back.
Also I'm not afraid to admit, I partly came up with a doughnut-shaped planet filled with hybrids including human-equine ones, just for the pun of naming it CENTORUS. :P
This thing would collapse under is own weight, unless the angular speed is really high. but not too high, or you would end with some kind of interstellar buzzsaw. for something as large as Earth, it would need around 1 turn per three hours. but you couldn't live on the outside of the ring. supersonic wind aren't really good to build stuff.
This thing would collapse under is own weight, unless the angular speed is really high. but not too high, or you would end with some kind of interstellar buzzsaw. for something as large as Earth, it would need around 1 turn per three hours. but you couldn't live on the outside of the ring. supersonic wind aren't really good to build stuff.
Yeah, there's a reason in the Ringworld books, the eponymous Ringworld is made out of Sci-Fi bullshitium with a comparatively thin rock and soil covering rather than just rock and soil.