This shows that at very small moons etc they will be finite.
OCD is fine, we want to get everything right
In the current build the Moon has a very early prototype of a new feature we are trying out to make Minecraft render a spherical planet, not a flat world. There are a few current issues with that, including the camera angle oscillating as you move around (you will see the stars moving, for example), also mobs and other entities will be rendered in the wrong position if they are not in the player's own chunk. This feature will eventually not be implemented on the Overworld's Moon, but on other smaller moons which might be seen some time in Galacticraft's future.
By the way, did you try to build a space station with spin thrusters yet?
OCD is fine, we want to get everything right
In the current build the Moon has a very early prototype of a new feature we are trying out to make Minecraft render a spherical planet, not a flat world. There are a few current issues with that, including the camera angle oscillating as you move around (you will see the stars moving, for example), also mobs and other entities will be rendered in the wrong position if they are not in the player's own chunk. This feature will eventually not be implemented on the Overworld's Moon, but on other smaller moons which might be seen some time in Galacticraft's future.
By the way, did you try to build a space station with spin thrusters yet?