In a significant milestone for the search for extraterrestrial life, astronomers have confirmed the existence of an atmosphere surrounding LHS 1140b, a rocky, Earth-like exoplanet located 48 to 49 light-years from Earth. This discovery marks the first time researchers have observationally confirmed an atmosphere on a rocky planet residing within a star’s habitable zone.
A Landmark Discovery in the Search for Life
Since the first exoplanet discovery in 1992, scientists have identified more than 6,200 worlds orbiting distant stars. While astronomers have previously detected atmospheres around gas giants and “sub-Neptunes,” finding a rocky, Earth-like planet with an atmosphere in the habitable zone—the region where temperatures allow liquid water to exist—has remained an elusive goal. According to lead author Dr. Collin Cherubim, formerly of Harvard University, LHS 1140b is the first rocky planet to have an atmospheric species directly identified.
The planet was originally discovered in 2017 using the transit method, which detects the slight dip in starlight as a planet passes in front of its host star. A new study, published in the journal Science, confirms the planet’s atmospheric composition by analyzing starlight that filtered through the planet’s envelope during these transits. Using an infrared spectrograph on the Magellan Clay telescope in Chile, researchers identified the presence of helium, which is escaping the planet into space.
Understanding the Planet and Its Host
LHS 1140b orbits a red dwarf star in the constellation Cetus. While red dwarfs are the most common stars in our galaxy, they are often volatile, frequently emitting intense radiation that can strip atmospheres away from orbiting planets. The confirmation that LHS 1140b has retained its atmosphere over billions of years provides evidence that rocky worlds orbiting these stars can indeed remain viable candidates for study.
The planet possesses a mass 5.6 times that of Earth and a radius 70% larger. It completes an orbit every 24.7 days at a distance of approximately 9 million miles from its host star. Despite this proximity, the planet remains within the “Goldilocks zone” because its host star is significantly smaller and cooler than the Sun, with surface temperatures ranging from 3,100°F to 5,800°F.
Scientific Implications and Future Research
The study highlights several key characteristics of LHS 1140b that define its potential for habitability:
- Atmospheric Shielding: The atmosphere acts as a necessary barrier, protecting the surface from ionizing radiation and helping to maintain the pressure required for liquid water.
- Composition: The planet is rocky, likely featuring an iron core, and researchers suggest it may contain significant amounts of water.
- Stability: The host star is considered relatively quiet, with few flares, which has likely contributed to the planet’s ability to hold onto its atmosphere.
While the detection of helium is a breakthrough, experts caution that this does not provide direct evidence of life. Furthermore, the signal has shown variability; researchers noted that while a helium signature was captured in 2024, it was not detected in 2025 observations. Dr. Cherubim and his team conducted extensive re-analysis to rule out false positives, such as contamination from Earth’s atmosphere, and remain confident in the initial findings.
The scientific community views this planet as a vital laboratory for astrobiology. As Jayne Birkby, a professor of astrophysics at the University of Oxford, noted, the discovery allows researchers to investigate how an exoplanet’s atmosphere reacts to extreme ultraviolet radiation from a host star, providing deeper insight into the surface conditions of worlds beyond our solar system.
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