Which habitable-zone planets can actually support life? A recent study uses a nearby planet — Proxima Centauri b — to examine how the presence and size of a land mass impacts the habitability of an ocean world.
A Target for Potential Life
In our galaxy, roughly 80% of stars are cool, dim M dwarfs — and one in six of these is thought to host an Earth-sized planet in its habitable zone. But being in a star’s habitable zone doesn’t guarantee a planet’s habitability! M-dwarf habitable-zone planets present valuable targets for observations and models to better understand which of these worlds can support life.
Artist’s impression of a cold, tidally-locked planet. Ice covers much of the planet’s surface, but the point directly facing the planet’s host star remains ice-free. [NASA/JPL-Caltech]Most habitable-zone planets around M dwarfs are likely tidally locked: one side of the planet experiences constant day; the other, constant night. Nominally, this would cause only one region of the planet to be heated — the point closest to the star — and the rest of the planet would be locked in darkness and ice. But if the planet is covered in a dynamic ocean, heat can be transported around ...