Kepler-442 b

Kepler-442 b is a rocky world about 1.34 times Earth's radius with a mass of 2.36 Earths, orbiting a cool K-dwarf star every 112 days at a distance of 0.409 AU. Its equilibrium temperature of 241 Kelvin—roughly 32 Kelvin colder than Earth's mean—places it in the habitable zone's cooler edge, where liquid water could persist if sufficient atmospheric greenhouse warming exists. The planet's density of 5.39 g/cm³ is consistent with an Earth-like rocky composition, though its interior structure and outgassing history remain unknown from transit data alone. At 1,190 light-years away, Kepler-442 b is too distant for direct atmosphere study with current telescopes, leaving key questions unanswered: whether it retained a magnetic field to shield against the K-dwarf's stellar wind, whether it ever held enough volatile compounds to build a habitable atmosphere, and whether tidal heating or interior cooling has rendered it geologically dead. Its relatively high habitability score of 88 reflects the favorable equilibrium temperature and rocky nature, yet these measures cannot resolve whether the planet is actually alive with plate tectonics and outgassing, or a sterile ball. Kepler-442 b remains a prime target for future biosignature surveys precisely because its temperate orbit and Earth-like mass make it neither obviously habitable nor obviously ruled out.