Rūta

Rūta presents as arctic silver, with cryo-volcanic vents releasing frozen plumes, with a solitary moon tracing a low, steady orbit. Surface temperatures range from -220 to -140°C at 0.8 atm, with sublimation plumes rising into the thin upper atmosphere. At 3,238 km across, the surface material is primarily water-ice and nitrogen-ice mixed with rocky core material. The ice here is not fragile polar frost — at 3,238 km across, it is kilometres-thick, ancient, and under pressure that would crush any conventional structure.