Astronomers confirm rocky exoplanet with atmosphere in habitable zone
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Astronomers at the Harvard-Smithsonian Center for Astrophysics have confirmed the first rocky exoplanet with an atmosphere located in the habitable zone, 48 light-years away. The planet, LHS 1140 b, retains an atmosphere that has persisted for at least 3 billion years, according to findings published in Science this week. The discovery marks a milestone in the search for Earth-like worlds, even as the planet's atmosphere appears very different from Earth's.
The Discovery
Researchers detected helium signatures escaping from LHS 1140 b, a rocky exoplanet orbiting a cool red dwarf star. The planet, first identified in 2017, lies within the habitable zone where liquid water could exist. Observations from 2024 and 2025 provided the spectral evidence for helium, confirming the presence of an atmosphere. The team used physical models to reconstruct gas escape, showing the atmosphere has persisted for at least 3 billion years.
Habitability Constraints
While LHS 1140 b meets three key criteria—rocky composition, habitable zone location, and atmosphere—its upper atmosphere differs markedly from Earth's. The escaping helium suggests a lower atmosphere possibly rich in nitrogen, carbon dioxide, or carbon monoxide. The presence of liquid water or surface oceans remains unconfirmed. The study validates the detection technique but underscores that habitability requires further investigation.
Closest Rocky Exoplanet Confirmed
HD 219134b, the nearest rocky exoplanet to Earth, was confirmed using NASA's Spitzer Space Telescope. Located 21 light-years away in the Cassiopeia constellation, the planet is 1.6 times larger than Earth. Its orbit is too close to its host star for liquid water, unlike LHS 1140 b.
Publication Details and Significance
The study was published in the journal Science on July 17, 2026. This detection marks the first confirmed atmosphere on a rocky exoplanet in the habitable zone.
What's Next
Scientists plan to observe LHS 1140 b with more powerful instruments to fully characterize its atmosphere and search for surface oceans. It remains unclear whether the planet's lower atmosphere contains gases compatible with life as we know it.
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Astronomers confirm rocky exoplanet with atmosphere in habitable zone
