05/06/2026
A new model from Stanford calculates the minimum planetary size needed to hold onto an atmosphere in the habitable zone. The verdict: below 0.8 Earth radii, atmospheres don't last. Published in The Planetary Science Journal, STEHM redraws the target list for the search for life beyond Earth.
Researchers at Stanford have developed STEHM, the Smaller Than Earth Habitability Model, to calculate the lower size limit for atmospheric retention in the habitable zone of sun-like stars. The model finds that planets at or above 0.8 R⊕ can sustain CO2 atmospheres for over 10 billion years, while...