Thanks! Glad you're enjoying it. On to the next bit!
The Solar System
In the real world, the moon orbits the earth and the earth orbits the sun. They have to orbit because they are constantly being pulled toward each other, so if they didn't move they'd collide. None of this is the case in the Minecraft universe.
In Minecraft, we can tell that the moon and sun are fixed in place because they don't move across the field of stars. We also know that in Minecraft most things do not fall toward the ground. Therefore, I propose that the same lack of gravity applies in the larger universe, and the moon and world-cube are hovering above the sun in the same way an unsupported stone or dirt cube hovers above a lava lake.
We can also see that the sun, world, and moon are perfectly aligned on the same grid. This is also similar to what we see on the ground, where all fixed cubes are aligned to the same grid. My suggestion is that the sun establishes a grid that the moon and the world are locked into.
However, the world is spinning within its space in the grid. This suggests that there can be unaligned grids within a larger grid area. We have seen this on the ground too - when you drop a block without placing it, it spins in place. The bodies and limbs of mobs are also rectangular but not aligned with the world's grid.
Are there other planets in this solar system? There could be. Another cube could be hiding behind the moon or on the other side of the sun. Any planets hovering above the other faces of the sun should be visible as stars aligned to the sun's grid or spinning, directly in one of the cardinal directions from the sun in the sky. Planets in the northern or southern direction would be only visible at dawn or dusk, so they may be hard to see.
The other stars
The other stars are square, so we can assume they are also cubes. I am guessing that they are other suns, sufficiently far away that they have their own grids with possibly their own cubical planets and moons. (We know they are not other players' games, since they would see different star patterns.)
Here are some educated guesses about the structure of the Minecraft universe.
The World
The sun, moon, and stars appear to be fixed in relation to each other as they spin around the world. Since Minecraft is, to some degree, a reflection of the real world I'm going to assume that the world is spinning and the celestial bodies are staying still. Since almost everything in Minecraft is a cube, I'm also going to assume the world is a cube. (This is more or less the principle of "As above, so below".) We play on one of its faces as the entire cube spins around. (Being able to see the lower Void contradicts this, but since Mojang seems to block off the floor of the world as much as possible I'm going to ignore that.)
Since the Nether stays in sync with the surface world but is 8 times smaller I think it's probably inside the world-cube, 1/8 as far from the center as the surface is.
How big is the surface? Since the Far Lands are an accepted part of the game, I think they must be included. I'm going to take the point 32,000,000 meters out where physics stops working as the edge of the world. That makes the world-cube 6.4x107 meters across. This is 5 times the width of Earth and about half that of Saturn.
The idea of a world-cube also suggests a land of eternal twilight on the north and south faces, where the sun and moon both peek over the horizon as they chase each other around, but I doubt we'll ever see that in game.
3
Thanks! Glad you're enjoying it. On to the next bit!
The Solar System
In the real world, the moon orbits the earth and the earth orbits the sun. They have to orbit because they are constantly being pulled toward each other, so if they didn't move they'd collide. None of this is the case in the Minecraft universe.
In Minecraft, we can tell that the moon and sun are fixed in place because they don't move across the field of stars. We also know that in Minecraft most things do not fall toward the ground. Therefore, I propose that the same lack of gravity applies in the larger universe, and the moon and world-cube are hovering above the sun in the same way an unsupported stone or dirt cube hovers above a lava lake.
We can also see that the sun, world, and moon are perfectly aligned on the same grid. This is also similar to what we see on the ground, where all fixed cubes are aligned to the same grid. My suggestion is that the sun establishes a grid that the moon and the world are locked into.
However, the world is spinning within its space in the grid. This suggests that there can be unaligned grids within a larger grid area. We have seen this on the ground too - when you drop a block without placing it, it spins in place. The bodies and limbs of mobs are also rectangular but not aligned with the world's grid.
Are there other planets in this solar system? There could be. Another cube could be hiding behind the moon or on the other side of the sun. Any planets hovering above the other faces of the sun should be visible as stars aligned to the sun's grid or spinning, directly in one of the cardinal directions from the sun in the sky. Planets in the northern or southern direction would be only visible at dawn or dusk, so they may be hard to see.
The other stars
The other stars are square, so we can assume they are also cubes. I am guessing that they are other suns, sufficiently far away that they have their own grids with possibly their own cubical planets and moons. (We know they are not other players' games, since they would see different star patterns.)
6
The World
The sun, moon, and stars appear to be fixed in relation to each other as they spin around the world. Since Minecraft is, to some degree, a reflection of the real world I'm going to assume that the world is spinning and the celestial bodies are staying still. Since almost everything in Minecraft is a cube, I'm also going to assume the world is a cube. (This is more or less the principle of "As above, so below".) We play on one of its faces as the entire cube spins around. (Being able to see the lower Void contradicts this, but since Mojang seems to block off the floor of the world as much as possible I'm going to ignore that.)
Since the Nether stays in sync with the surface world but is 8 times smaller I think it's probably inside the world-cube, 1/8 as far from the center as the surface is.
How big is the surface? Since the Far Lands are an accepted part of the game, I think they must be included. I'm going to take the point 32,000,000 meters out where physics stops working as the edge of the world. That makes the world-cube 6.4x107 meters across. This is 5 times the width of Earth and about half that of Saturn.
The idea of a world-cube also suggests a land of eternal twilight on the north and south faces, where the sun and moon both peek over the horizon as they chase each other around, but I doubt we'll ever see that in game.
More later.