Rocky 'Super-Earth' LHS 1140b Shows Signs of Atmosphere

Astronomers have detected compelling evidence suggesting that the rocky exoplanet LHS 1140b, located 49 light-years from Earth, may possess an atmosphere. This finding, announced on July 16, 2026, in the journal Science, could position the planet as a prime candidate for supporting life beyond our solar system. LHS 1140b is classified as a “super-Earth,” with a mass approximately five times that of our own planet. It orbits its host star within the “Goldilocks zone,” a region where temperatures are neither too hot nor too cold, potentially allowing liquid water to exist on its surface.

Collin Cherubim, a planetary scientist and lead author of the study, stated that the planet's mass and radius measurements indicate it is predominantly rocky. "It appears to be consistent with Earth, meaning it might have an iron core and a silicate mantle, plus some sort of low-density component, which is probably a combination of water and, now we know, an atmosphere," Cherubim, a NASA Sagan Fellow at the University of Chicago who conducted the research during his doctoral studies at Harvard University, explained.

Atmospheric Detection Challenges

Detecting atmospheres around small, rocky exoplanets is an intricate process. Astronomers typically rely on observing planets as they transit, or pass in front of, their host stars. During these transits, starlight filtering through any existing atmosphere can reveal chemical signatures. While more than 6,200 exoplanets have been discovered since the 1990s, and evidence of an atmosphere was found on a gas giant in 2001, finding one on a rocky planet in the habitable zone would be a first.

Cherubim developed a model hypothesizing that many planets initially form with hydrogen and helium atmospheres. As they evolve into rocky bodies, they might shed most of their hydrogen but retain some helium, which is denser. Using the Magellan Clay telescope at Las Campanas Observatory in Chile in September 2024, Cherubim's team identified helium escaping from LHS 1140b, a key indicator for an atmosphere. "You’re stripping the hydrogen, keeping the helium, and you end up with this sort of helium world," Cherubim said. "We believe LHS 1140b is in that sweet spot, where it lost its hydrogen and it kept its helium, which is now slowly escaping." While helium alone might not sustain life, Cherubim is optimistic that other gases, like oxygen or water vapor, could be present. "We don’t have any other detections of any other molecules in the atmosphere yet, but I’m optimistic," he added. "I would go ahead and bet that we will find something eventually."

The host star for LHS 1140b is a red dwarf, the most common type of star in the universe. Planets orbiting these smaller, cooler stars are easier to study for atmospheric composition due to less stellar glare. However, red dwarfs are known for their intense activity, emitting high levels of X-rays and ultraviolet radiation that can strip away planetary atmospheres. "They’re really feisty, ferocious stars that emit lots of X-rays and ultraviolet radiation," Cherubim noted, "which are really bad for atmospheres because they heat them up, expand them and blow them off into space." Confirming an atmosphere on a rocky planet around such a star would significantly advance astronomical understanding. "Can rocky planets have atmospheres around red dwarfs? This is the first bona fide yes," Cherubim stated. "It’s kind of a sigh of relief for a lot of us. But the jury’s still out. Maybe this is a weird planet, and it’s an oddball, or maybe it’s the first of many. We don’t know yet."

Further observations in 2025, however, did not detect helium, leading to speculation about the variability of gas escape rates or sensitivity limitations. This discrepancy remains a significant mystery, with researchers planning new observation campaigns. Jason Dittmann, a study coauthor and assistant professor of astronomy at the University of Florida, expressed excitement about the potential for LHS 1140b to receive attention from major instruments like the James Webb Space Telescope and the Hubble Space Telescope. "I was starting to worry that maybe atmospheres around rocky planets weren’t that common or maybe red dwarfs weren’t very good planetary hosts," Dittmann said. "So I think finding a positive example of a rocky planet with an atmosphere is really significant. It’s what we’ve been hoping to find for years. What else is there besides helium? Can we maybe find water next? Something else? The significance in this result lies in all the excitement about what other questions we can maybe ask next." Dittmann, who led the team that originally discovered the exoplanet in 2017, sees LHS 1140b as a crucial step. "I hope we’ll start seeing more rocky planet atmospheres over the next few years. And it’ll be really exciting to compare these planets to each other and see what makes them different," he added.

Other experts, like Ana Glidden, a postdoctoral researcher at MIT, acknowledge the groundbreaking nature of the findings, calling it the strongest evidence yet for an atmosphere on a rocky planet in the habitable zone. Michaël Gillon, research director at Belgium's University of Liège, noted the study's potential significance but urged caution due to the single detection of helium. "The helium signal was detected only once and was absent in follow-up observations in 2025," Gillon wrote. "The lack of a second detection calls for caution and before drawing conclusions about the nature of any underlying atmosphere, there is a need to establish that the helium signal is genuinely associated with the planet and reproducible." If confirmed, the discovery of an atmosphere on rocky exoplanet LHS 1140b would profoundly impact the search for extraterrestrial life.