Astronomers have confirmed the presence of an atmosphere on the rocky exoplanet LHS 1140 b. The planet orbits a red dwarf star in its habitable zone, some 48 light years from Earth. This marks the first time such a detection has been made for a world of this kind in that orbital sweet spot.
The observations came from watching the planet pass in front of its star. An infrared spectrograph on the Magellan Clay telescope at Las Campanas Observatory in Chile picked up the signal. Helium showed up in the upper atmosphere. The results appear in a peer-reviewed paper published in the journal Science.
LHS 1140 b was first spotted in 2017. It weighs about 5.6 times as much as Earth and measures roughly 1.7 times our planet's radius. The host star is relatively quiet, producing few flares. That detail matters because many red dwarfs bombard their planets with intense radiation.
What the detection actually shows
The helium signal comes from gas escaping the upper atmosphere. It does not tell us about conditions on the surface. No biosignatures have been found. The detection falls short of proving liquid water exists or that the planet could support life.
Earlier observations had caught atmospheres around gas giants, sub-Neptunes, and rocky planets well outside the habitable zone. This result stands apart. It offers the strongest evidence yet for an atmosphere on a rocky world in the right place for potential habitability. Yet the distinction between an atmosphere and a place where humans or other life could thrive remains vast.
The detection relates to gas escaping from the upper atmosphere and does not confirm conditions on the surface or the presence of biosignatures.
No atmosphere turned up around the other rocky planet in the same system, LHS 1140 c. That contrast sharpens the interest in b. Still, researchers stress the limits of what current instruments can reveal. The work rests on careful data collected mainly in 2024, with follow-up checks in 2025 that first missed the helium line before re-analysis confirmed it and ruled out contamination from Earth's own air.
