Ohh... random thought along the lines of Lagrange points ... then I gotta go do work.
Ok we got an invisible star or two in some systems so we don't overload on orbital colonies. Give it level 5 cloak, since it's not really an object, but level 4 cloak in gravitic.
So you could find the point once you researched high enough in the Gravitational tree. (Yeah, I know anyone who can draw an equilaterial triange can find Lagrange points, just working on technobabble explanations here - it takes some work to find a stable point in the system)
Say, here's where I'm getting my Lagrange point information:
NASA web page