I also keep thinking about this and how we can make Galacticraft more "space like" without spoiling the core Minecraft aesthetic of:
1. flat world
2. circles are squares, spheres are cubes
One option I have toyed with - and this is really going to annoy you guys, because the code to do this is
actually in Galacticraft right now, it's been there since around June 2014 only it's disabled - is to make the world
not flat.
Screenshot 1 (early concept test, a lot of issues and nasty gaps but it shows you the idea:
Screenshot 2 - a lot of improvements, still a minor gap / glitch, that's now invisible in the latest version
That's still a possibility for some future version of Galacticraft, maybe only for "small" moons. Please do not ask questions about when or whether this will ever see the light of day.
The bigger issue is: what should the Overworld look like from a Space Station. I would love to add: a terminator line, an atmosphere fringe, and clouds.
Oh wait: somebody already suggested that and made a mock-up:
http://forum.micdoodle8.com/index.php?threads/bigger-earth.4435/page-2#post-33953
It feels like we're stuck with square planets. A rotating cube just looks wrong, and raises unanswerable questions like how can players get to the other face of the cube. But what do you guys think about a terminator line moving across the square planet, as the sun rises? We can probably do that. It's not consistent with the vanilla game physics (i.e. it's the same time of day everywhere on the Overworld). But think of the square planet as being like a Mercator projection of a planet which is in fact spherical, only because it's Minecraft you can't see the curve, the curve has to be made flat (i.e. Mercator projection).
We could also maybe look at "Low Earth Orbit" space stations where the terrain underneath changes, and is more zoomed in.
I don't have a problem at all with the Minecraft world wrapping around so that e.g. x=-10000 joins on to x=10000, if we are talking about graphical effects in orbit, and space station orbital paths. As has been said, a lot of servers use a WorldBorder plugin to limit the size of the world. We could make the wraparound configurable in Galacticraft.