BTW, the sector sight obscuration ability will not hide a planet from the AI.
I created a map in which I used this ability to 'hide' ringworlds until the tech allowed someone to find them.
Well, what I didn't know is that a player's colonization minister WILL see them and sent colony ships to that location. ( I don't normally use this minister.) However I am told that you still cannot colonize the planet until you have the tech to see the planet. So if your intent is to keep these planets uncolonized, then this ability IS the proper one!
