Rogue-Planet Moons Could Harbor Oceans for Billions Without Sunlight

A 2026 modelling study from LMU Munich and collaborators suggests an Earth‑sized moon orbiting a Jupiter‑like rogue planet could maintain surface liquid water for up to about 4.3 billion years without any starlight, if enveloped in a thick (≈100 bar) hydrogen atmosphere and driven by tidal heating—though this relies on favorable assumptions, omits many real‑world complexities, and no such exomoons have been observed yet.