I'm just planning on restarting my campaign after it's extended hiatus and was thinking abstractly about distances between the stars in the Third Horizon, and potentially the 2nd, 1st and even 4th horizons.
Am I correct in thinking that the portals linking systems have no direct correlation to the position in the galaxy and distance between two linked systems. Thus for example Kua and Hamura may be hundreds of light years apart, while Eanu and Menkar, at opposite ends of the horizon, may only be a dozen light years apart or less?
If this is true, then there is no reason why a whole new network of portals might lie relatively close to the Third Horizon, perhaps through as a yet undiscovered portal around one of the more distant stars in a trinary system.
Which then brings us neatly to the original Zenith mission to Aldebaran. We know the distance from Earth to Aldebaran is around 65 light years, and we know that the journey took a long, long time. Aldebaran doesn't have any really close neighbours so this adds strength to the theory that the portals aren't relative to actual distance. But it also means that there is no reason why other visitors to the system from elsewhere in the surrounding 65LY sphere may also have decided to risk the long journey here, especially as we know observations had indicated the possibility of life supporting planets. Visitors who could turn up at any time...
I'm not sure I have a use for this just yet, as we have Emissary Lost looming large but it has huge potential.
Happy gaming all