Tidal Locking
Rotation-orbit synchronization in which a planet always shows the same face to its host star, producing permanent day and night hemispheres with extreme thermal contrast — common for rocky planets in the close-in habitable zones of M dwarfs. Long treated primarily as an obstacle to exoplanet-habitability (atmospheric collapse/stripping on the night side, extreme day-side heat), distinct from tidal-heating (frictional interior heating from orbital eccentricity).
2026 laboratory reframing
daisuke-noto and collaborators (JAMSTEC/Hokkaido University) built a laboratory glycerol-tank analog of a tidally locked planet’s mantle and found a stable, single-loop convection pattern (dayside upwelling, nightside downwelling) with Earth-comparable heat-transport (Nusselt number) efficiency. This suggests some tidally locked worlds could sustain localized, mid-latitude geothermal environments favorable to life despite day/night surface extremes, and could produce non-dipole magnetic fields distinct from Earth’s. See src-tidally-locked-exoplanet-habitability-2026-07.