Orbit (period): 0.58 au (161.3 T-days)
Orbit (ecc.): 0.02
Radius: 3,680 miles
Mass: 4.3 x 1024 kg
Density: 4.96 g/cm3
Surface gravity: 0.84 g
Axial tilt: 7.9°
Rotation period: 23.1 T-hours
Black-body temperature: 347 K
Surface temperature (avg.): 1,015 K
Atmosphere: Extremely dense, furnace-hot, primarily CO2.
Atmospheric pressure (sfc.): 117.6 atm
Hydrographic coverage: 21%
Sialhaith may not actually be one of the less pleasant hells, but if you wanted to build one, it would undoubtedly be where you’d go real-estate shopping.
It’s a “wet greenhouse”, consisting of furnace-heat over eroded rocky deserts, moistened by small oceans of boiling acid, with an atmosphere primarily of carbon dioxide and water vapor, mercifully concealed from space by its impenetrable belts of caustic, lemon-yellow, sulphuric-acid smog clouds. (They wrapped probes in platinum hulls just to find that much out.) If it is not the single least hospitable place in the entire System, the Sialhaith Extreme Tourism Advocacy Branch would like to know.
Naturally, in the future, people tried to ecopoese it. It didn’t stick: in the end, the residents of the aerostats – it’s very easy to build cities that are naturally buoyant in the Sialhain atmosphere – that were intended to monitor the ecopoesis process ended up buying out the project, having decided that they liked their lifestyle and its uniqueness just the way it was.
There’s very little on the surface itself but some minor scientific and resource-gathering outposts, and small-scale dome-warrens belonging to the sort of person who demands that their lifestyle be the absolutely most challenging available.
Oh, and Fort Inferno, because Legionary drill instructors also demand a lifestyle that’s the absolutely most challenging available.