Scientists have identified an atmosphere surrounding LHS 1140b, a rocky exoplanet located 49 light-years from Earth in the habitable zone of its host star. This discovery represents a significant milestone in the search for potentially habitable worlds beyond our solar system, as it marks the first time an atmosphere has been observationally confirmed on a rocky planet capable of maintaining liquid water on its surface within such a zone.
The planet was originally discovered in 2017 and orbits a small red dwarf star in the constellation Cetus. LHS 1140b has a mass approximately 5.6 times that of Earth and a radius 70 percent larger. While the planet shares some characteristics with Earth, including similar composition and temperature ranges, it differs in significant ways—notably that it is tidally locked and may contain substantially more water than Earth does. Researchers used an infrared spectrograph attached to the Magellan Clay telescope in Chile to observe the planet as it passed in front of its star, detecting helium escaping from the planet’s upper atmosphere. Data collected in 2024 revealed the helium signal, though subsequent observations from 2025 did not detect the gas, prompting researchers to conduct thorough analyses to rule out alternative explanations and confirm the authenticity of their findings.
According to lead researcher Dr. Collin Cherubim, the discovery indicates that LHS 1140b possesses the essential conditions for habitability: a rocky composition, temperatures that allow liquid water to exist, an atmospheric envelope to retain water and shield the surface from harmful radiation, and a relatively stable host star with infrequent flare activity. The research team found no atmosphere around LHS 1140c, another rocky planet orbiting the same star.
Other scientists in the field have emphasized the significance of this detection. Experts noted that small red dwarf stars are the most common stellar type and offer the best opportunities for studying nearby rocky exoplanets in habitable zones, though such stars typically strip away planetary atmospheres through their activity. The variability of the atmospheric signal at LHS 1140b demonstrates how the planet’s atmosphere interacts with intense radiation from its host star. However, some researchers cautioned that since the detected atmospheric gases originate from the upper atmosphere rather than regions closer to the surface where life would be expected to emerge, the findings do not directly establish conditions for biological viability.
Originally reported by The Guardian. Read the full story →