Helium escaping from the atmosphere of a nearby rocky exoplanet orbiting in a habitable zone

September 3, 2026| Source: Science

Observations of highly irradiated gas giant exoplanets have shown helium escaping from their atmospheres. There is limited evidence for atmospheres on rocky exoplanets, perhaps because they have already escaped. We report near-infrared spectroscopic observations of LHS 1140b, a rocky exoplanet that orbits in the habitable zone of a nearby low-mass star. The transit spectra show absorption by helium escaping from the planet’s atmosphere. Helium absorption is detected in 2024 but not in 2025, indicating time-variable atmospheric escape. We interpret these results as indicating an upper atmosphere dominated by helium and depleted in hydrogen, with other volatile species trapped at lower altitudes, which is consistent with atmospheric fractionation models. No helium absorption is detected for LHS 1140c, a smaller and more strongly irradiated exoplanet in the same system.

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Helium escaping from the atmosphere of a nearby rocky exoplanet orbiting in a habitable zone

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Extensive glacier loss in the coterminous United States.

Reaction-based cryo-EM resolves the continuous conformational spectrum of CTP synthase catalysis.

GTP orchestrates CTP synthase via an allosteric effector-cycling mechanism.

Antiferromagnetism and tightly bound Cooper pairs induced by kinetic frustration.

Coordinated transformations of the labyrinth and occiput during the dinosaur-bird transition.