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Building a Hollow Earth World

J Q Kaiser

Dreamer
My latest story takes place inside a hollow Earth. I tend to overthink my explanations for how things work. For example, I am wondering how light would work in a hollow earth if the center of the Earth had a small, bright star suspended in the middle with a revolving layer of rock (or something else) that blocked 60 - 80% of the star's light (imagine a tennis ball with a slice cut out to make it look like a 3D Pac-Man). Good so far, right? Well what happens with the light that escapes? Would it simply bounce around inside hollow Earth so that it is never truly night/dark anywhere? Or would you still have areas of darkness and night?
 
Wanted to answer this earlier and am finally getting around to an answer using my world.

On Eld the drow have summoned a giant chunk of the sun that takes the form as a rather large diamond of sorts imaginatively called a sun stone. Embedded into the stone above their primary underground giant cavern and capitol city Paradise. They have it set to slowly go dark and let the cave lichens light up to make it look like a stars. True it's all based on spells and magic, but it's how they do it and they summon more pieces of the sun as needed for other underground cavern systems or to light the houses. Maybe not exactly what you're looking for but just what I use.

Honestly it comes down to you. Though a place with no night at all would likely have some very well adapted creatures to that particularly very niche ecosystem. Could always find a way to make it go out with a vague explanation or even a decent one. Though even with a hollow earth there's got to be plenty of cave systems and the like where the light will not go or simply can't reach. Though if you are using the revolving plate layer, it shouldn't be any more then night actually coming like it normally does. Though maybe a bit faster. If it's a round world in the first place.
 

Vaporo

Inkling
Exactly how much space does the sun and hollow sphere take up in the center? If I were to look up in the "sky," would it appear roughly the size of the real sun? Bigger? Smaller? Does it cover almost the entire "sky," or just a small portion? If it doesn't take up much, then the sky will be fairly bright at "night," and the best you will get is probably just a sort of twilight. If it covers a significant portion, though, then the "sun" will block its own reflected light, making the "night" side dimmer.

Imagine going into a dark room and shining a spotlight at the opposite wall.That's about the kind of reflection levels you'd get in your scenario.

Honestly, it looks you're making this harder on yourself that it has to be. It sounds like you're running with this idea (hollow earth with a sun in the middle) and then trying to justify things like a day/night cycle with science, even though the original idea isn't very scientific. I've done the exact same thing. Could the "sun" in the middle just go through a cycle of bright/dark every 24-ish hours, instead of the convoluted Pac-man sphere thing? Does there even need to be a night cycle? Could it just be day all the time? Maybe the magma sphere and the "sun" are one and the same, and there is only a thin strip on one side that is actually emitting light? (since that seems slightly easier to justify) Is this whole system artificial, or is it supposed to be natural? If it's supposed to be natural, it will be very difficult to justify without some serious magic at work.
 

skip.knox

toujours gai, archie
Moderator
I recommend doing a net search. There's good information out there. See what Halley, Symmes, even Verne, have had to say on this.
 
What you're describing is essentially a Dyson Sphere, an admittedly science-fictional mega-structure in which a star is completely (or almost completely) enclosed in an artificial sphere; the inner surface receives the star's energy, making it habitable. For example, think a sphere around our Sun with a radius equal to the Earth's distance from it. Virtually all of the Sun's energy would be trapped over a surface area equal to about 550 million times that of Earth. That makes for a LOT of living room!

You could mine the Dyson Sphere concept to create your "hollow earth", but without ever using the term "Dyson Sphere", "planet", etc. (unless, of course, it suits your story to do so). You could also make it far smaller than our "Terrestrial Dyson Sphere", if that suited you; the result would be a much hotter surface but, of course, this is fantasy so that could not be a problem at all because MAGIC!

Anyway, reading up on Dyson Spheres might help you crystallize your thinking around your "hollow earth". See Dyson sphere - Wikipedia
 

Saigonnus

Auror
Perhaps mages of old simply manufactured a “sunstone” or some such thing and it serves to light the interior space of the hollow world. Maybe it even has a cycle of recharge (a.k.a night) where it is dimmer, like the moon, and each citizen gives a tiny bit of life force to reignite it for the next day.
 

SithLord

Dreamer
You could always use a "mystical" energy source. For example, Volkisch legends of Imperial Germany began to believe in a mystical source called Vril which became integrated into Theosophy and Nazi Occultism.
 
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