LHS 1140b, a super-Earth exoplanet located 49 light-years away, has emerged as a top candidate in the search for extraterrestrial life after scientists detected promising signs of an atmosphere and a predominantly rocky composition within its star’s habitable zone.
The Discovery of LHS 1140b and Its Rocky Composition
Astronomers have detected promising indicators that an exoplanet orbiting a star 49 light-years from Earth possesses an atmosphere. This development places the celestial body at the forefront of candidates potentially capable of harboring life. The object, designated as LHS 1140b, carries a mass roughly five times that of Earth, landing it firmly in the super-Earth classification.
The exoplanet orbits its host star inside the habitable zone, frequently termed the “zona Ricitos de Oro.” In this region, surface temperatures avoid extremes, theoretically allowing liquid water to pool on the surface. “We believe that it is also a predominantly rocky planet, based on the measurements of its mass and its radius, which allow us to estimate its density,” stated Collin Cherubim, a planetary scientist and the lead author of a study on the finding published on July 16 in the journal Science.
Data gathered by researchers points toward structural similarities with Earth. According to Cherubim, a NASA Sagan Fellow at the University of Chicago who conducted the research during his doctoral studies at Harvard University, the planet likely features an iron core and a silicate mantle, alongside a low-density component identified as water and an atmosphere.
Stellar Context and the Red Dwarf Dilemma
Since astronomers identified the first exoplanets in the 1990s, more than 6,200 extrasolar worlds have been cataloged. In 2001, the Hubble Space Telescope found evidence of an atmosphere surrounding a gas giant exoplanet situated 150 light-years away. If upcoming observations validate current data, LHS 1140b will become the first rocky world in another star system’s habitable zone confirmed to have an atmosphere.
Analyzing distant rocky atmospheres remains technically challenging due to the small physical size of these worlds and the extreme thinness of their gaseous envelopes. To overcome this hurdle, researchers must wait for a transit event, where the planet crosses in front of its host star. Much like a solar eclipse, starlight filtering through the planetary atmosphere exposes distinct chemical signatures.
The host star of LHS 1140b is a red dwarf, which stands as the most common stellar classification in the universe. Red dwarfs present distinct observational advantages because their smaller size and lower temperature produce minimal glare, simplifying atmospheric analysis. However, these stars possess volatile characteristics. “They’re really temperamental, fierce stars that emit massive amounts of X-rays and UV radiation,” Cherubim explained. “That is very detrimental to atmospheres because it heats them up, expands them, and blows them out into space.”
Atmospheric Evolution and Helium Signatures
Proving that a rocky world can retain an envelope around a red dwarf represents a major milestone for astrophysics. “Can rocky planets retain atmospheres around red dwarfs? This is the first really solid ‘yes,'” Cherubim noted.
To locate the atmosphere, Cherubim built a model based on the premise that many planets form with hydrogen-and-helium-dominant envelopes. As these worlds evolve, most hydrogen escapes into space, while heavier helium can remain trapped. Using the Magellan Clay telescope at the Las Campanas Observatory in Chile, researchers detected helium escaping from LHS 1140b in September 2024.
During a follow-up observation in 2025, however, the team failed to record the helium signal. Researchers attribute this discrepancy to potential fluctuations in the rate at which helium bleeds off the planet, pushing the signature below current instrument sensitivity thresholds. Ana Glidden, a postdoctoral researcher at the MIT Kavli Institute who was not involved with the study, emphasized that further observations remain vital to explain the conflicting data points between the 2024 and 2025 campaigns.
Future Observational Campaigns and Expert Outlook
The scientific community plans intensive follow-up campaigns. Instrumentation such as the James Webb Space Telescope and the Hubble Space Telescope will target the system. “Everyone who can observe it is going to point their instruments at it,” Cherubim stated.
Co-author Jason Dittmann, an assistant professor of astronomy at the University of Florida who led the team that initially discovered LHS 1140b in 2017, expressed cautious optimism regarding the path forward. “I was starting to worry that atmospheres on rocky planets weren’t very common, or that red dwarfs were bad places for planets,” Dittmann wrote. “So finding a positive example of a rocky planet with an atmosphere is really meaningful.”
"The helium signal was only detected once and was absent in the 2025 follow-up observations," Gillon wrote. "The lack of a second detection calls for caution. Before drawing conclusions on the nature of any underlying atmosphere, we need to prove that the helium signal is genuinely associated with the planet and reproducible."
