Astronomers have discovered an Earth-size planet, SPECULOOS-3 b, orbiting a red dwarf star 55 light-years away. The planet is tidally locked to its star, constantly exposed to intense radiation that has eroded away its atmosphere. Although not habitable for life as we know it, SPECULOOS-3 b provides a unique opportunity to study the geology and chemical composition of an airless, rocky exoplanet.