Nature Communications Planetary envelope

The exoplanet LHS 3844b and its parent star LHS 3844. The planet's close orbit, lasting only about 11 hours, likely makes it a tidally locked world, where the same side always faces the star. Credit: NASA.

New study: Even a “day-night locked” planet may contain more stable regions than previously thought

On an extreme world such as a gravitationally locked planet, relatively stable conditions, and perhaps even local areas that are not entirely hostile, may develop beneath the surface.