Earth-Size "Lone Wolf" Planets May Host Life
Theoretical worlds could harbor under-ice oceans, study shows.
Across the galaxy, countless "rogue" Earths may have been ejected from their planetary neighborhoods and are now zipping alone through space, previous studies have suggested. Now, new research says some of these worlds may have enough heat to support liquid water—and maybe life—without energy from a star.
Dubbed a Steppenwolf planet—since it "would exist like a lone wolf wandering the galactic steppe"—such a world could host a liquid ocean under an insulating layer of water ice and carbon dioxide snow, the study authors say.
Hydrothermal vents on the planet's seafloor may infuse the alien ocean with chemical energy sources. On Earth, nutrients from such deep-sea vents support bacteria and other life-forms that can exist without sunlight.