Moons orbiting wandering exoplanets could be habitable—with one catch

Provided they host thick, hydrogen-dominated atmospheres, moons orbiting free-floating exoplanets could retain much of the heat generated deep within their interiors by tidal forces. Led by David Dahlbüdding at the Max Planck Institute for Extraterrestrial Physics and Giulia Roccetti at the European Space Agency, a new study predicts that hydrogen could act as a potent greenhouse gas—potentially providing habitable conditions for billions of years after their host planets are first ejected from their stellar systems. The work has been published in Monthly Notices of the Royal Astronomical Society.