"Dumb question: how in the nine frozen hells does one manage to NOT SEE a bloody ring world ... ? Three billion times the surface area of the earth ... kinda hard to miss, n'est-ce pas? "
Divide that by the size of a star system.
That and the thing could be, oh, burried inside of a star that went red giant (not hot enough to melt whatever the world is made off), obscured by nebula.
Even the largest structure in the galaxy is invisible if there's something blocking the light between it and you.
Methinks a sphereworld would be rather hard to detect, too. Not a ring, but SPHERE. No light exiting from the resident star.
Phoenix-D