Astronomers announced Friday they've detected helium in the atmosphere of LHS 1140 b, a rocky exoplanet orbiting a dim red dwarf star roughly 49 light-years distant. The finding, published in the journal Science, marks the first tentative detection of an atmosphere on an Earth-like planet beyond our Solar System—a discovery that could reshape humanity's understanding of where life might exist in the cosmos.
The planet itself presents a compelling target for future research. LHS 1140 b is slightly larger than Earth and carries five times Earth's mass. It sits squarely within its star's habitable zone, where temperatures theoretically support liquid water on a planetary surface. Modeling suggests the world could be a water world, with an atmosphere that potentially contains water vapor, carbon dioxide, carbon monoxide, and small amounts of oxygen alongside the detected helium.
A Novel Detection Method
Collin Cherubim, who led the study while at Harvard University, explained the research breakthrough came through an unconventional approach. Rather than relying on the James Webb Space Telescope—which produced inconclusive results on LHS 1140 b and other rocky planets—his team deployed ground-based telescopes and a relatively new technique to detect helium's specific atmospheric fingerprint. "Nobody bothered looking for helium on a rocky, Earth-like planet, especially at Earth-like temperatures," Cherubim said. Scientists had previously assumed smaller planets wouldn't retain such light gases, which escape to space over time. Yet Cherubim's modeling predicted LHS 1140 b had "a relatively high probability of having this helium-dominated atmosphere." When the team looked, he noted, "Lo and behold, there it was."
The helium detection carries practical advantages for astronomers. Because helium can be found much farther from a planet's surface than other atmospheric gases, it's considerably easier to spot through ground-based observation. That efficiency matters. The technique has historically been applied only to large, gassy planets; testing it on rocky, Earth-like worlds represents a genuine methodological shift in exoplanet research.
Independent Verification and Caveats
Tom Evans-Soma, an astronomer at the University of Newcastle specializing in exoplanets, called the signal "very convincing" and described the finding as "very exciting." Evans-Soma noted that all previously detected rocky planets with atmospheric hints were far hotter and less hospitable than LHS 1140 b. He did flag one limitation: the helium signal was detected in one observation but not found in a second. Cherubim acknowledged the tentative nature of the result. "It's not like a smoking gun that it's a helium-dominated atmosphere, but it's consistent with the prediction," he said.
Evans-Soma's analysis of the team's modeling suggested two possible planetary scenarios. One involves minimal water and a thick atmosphere. The other—which Evans-Soma described as "very exciting"—depicts a water world with Earth-like rocky composition plus roughly 10 percent water by mass. "And I think that's very exciting," Evans-Soma said, "to imagine what such a planet might be like, especially in the habitable zone, where that water could be in the liquid form on the surface of the planet."
Cherubim emphasized the need for continued observation. He's already secured telescope time to examine a second candidate planet—one he describes as an LHS 1140 b twin, orbiting a similar star and possessing comparable size. "That one I'm really excited about," he said. The planet was first discovered in 2017, meaning researchers have now spent the ninth year since its initial detection working to understand its atmospheric composition.
Why This Matters:
This discovery carries significant implications for space exploration strategy and resource allocation. If Earth-like planets with stable atmospheres exist within habitable zones at distances we can actually observe and study with current technology, it reshapes the scientific case for future exoplanet missions. The finding demonstrates that ground-based telescopes can yield breakthrough results without massive expenditures on space-based infrastructure, suggesting a cost-effective pathway for continued atmospheric research. More broadly, identifying potentially habitable worlds relatively nearby—49 light-years is close in cosmic terms—establishes concrete targets for long-term exploration planning. The research also validates Cherubim's modeling approach, potentially opening new avenues for identifying candidates without relying solely on expensive space telescope time. For policymakers weighing space science budgets, this work illustrates how methodological innovation and creative use of existing ground-based facilities can produce discoveries that rival those from cutting-edge orbital observatories.