Green II

A very enigmatic habitable planet of the Green System.

Green II appears to have been hollowed out and is now a massive, mostly empty chamber. Despite this, the planet still has gravity for unknown reasons, and within the 'hollows', as this chamber is called, the gravity is reversed so that one can stand on the inside edge of the planet, and look up and see the rest of the planet interior at various angles. Green II was discovered like this, and it is very poorly understood.

Like most planets in the system, a kind of strange, green energy can be encountered. On Green II, this comes in the form of small electrical discharges happening fairly randomly. These have been known to disrupt technology at times but is not known to be fatal other than this. Sentient Robots might need repairs after being hit. This happens on both the inside and outside.

The inside of Green II is also lit by some light positioned at the center which slowly rotates and provides a day/night cycle to anyone living inside. Some large, ancient structures can be seen on the inside as well, with their function being unknown. These were also present when the HF discovered the planet. Due to the sheer number of unknowns with Green II, there are a large number of science structures built by the HF in attempts to find out more about Green II, but little is still known.

The strange planet is one of the better known tourist worlds in the system as well, being far safer than planets like Green I, and a lot of features that would seem absurd, even on other Green system planets. 

Green II has a primarily nitrogen-oxygen atmosphere similar to that of the Leosus Ring World, and a temperature higher than optimal for human life, though a human could survive being in the open with little protection gear. The interior of the planet is significantly colder and with a similar atmosphere composition, and the low temperatures might prove dangerous to the human genome if one is exposed to the cold for very long, so protection gear is worn. The temperature still gets much colder at the poles too, and much hotter near the equator, on the surface anyway.

Some people speculate that the source of gravity lies in the shell of the planet because that is where the strongest attraction is observed. It is known that the gravity is slowly reduced as one approaches the core, though the exact gravity at the core is presumed to be 0, but no probe has been able to reach it because they would crash into the rotating light. Some think that the light is what causes the gravity as well despite this, probably making use of some alien technology to manipulate gravity in such a strange way.

Perhaps one of the most interesting points is the Starchaser Ruin.