First atmosphere detected on a rocky planet in the habitable zone of a nearby star

An international team led by Collin Cherubim (Harvard-Smithsonian Center for Astrophysics) reports in Science the first direct detection of an atmosphere around a rocky, roughly Earth-sized planet orbiting in the habitable zone of a nearby star. The target is LHS 1140 b, a super-Earth about 48 light-years away, and the atmospheric signature is helium escaping from its upper layers.

The observation

Cherubim and colleagues used the Magellan Clay telescope at Las Campanas Observatory in Chile, equipped with an infrared spectrograph, to monitor the planet during transit. Just before the transit began and shortly after it ended, the spectra showed excess helium absorption imprinted on the starlight. That excess is the fingerprint of neutral helium streaming away from the planet, and the geometry of when it appears —tangential to the stellar disk— points to an extended, escaping atmosphere rather than contamination from the star itself.

LHS 1140 b was discovered in 2016 by Jason Dittmann, now at the University of Florida and co-author of the current paper. It orbits a low-mass, cool red dwarf and sits at a distance from its star where liquid water could be stable on a rocky surface, which is precisely what makes any atmospheric detection here scientifically decisive.

Why the helium has to be replenished

Helium is light and easy for stellar radiation to strip away. Complementary X-ray data on the host star allowed the team to estimate the rate at which the planet’s upper atmosphere is being eroded. That rate, applied over the age of the system —its red dwarf is around six billion years old— predicts that any primordial helium reservoir should already be gone. The fact that helium is still there, and still escaping, implies an active source: the atmosphere must be resupplied from the interior on geological timescales. In other words, LHS 1140 b appears not merely to have retained a thin veneer of gas but to sustain an atmosphere coupled to its interior chemistry.

That is a genuinely surprising result for a rocky planet around an M-dwarf. Whether small rocky worlds can hold on to substantial atmospheres against the fierce early stellar activity of red dwarfs has been an open question for years, and the community has been finding mostly bare rocks. This detection reopens the door.

What comes next

LHS 1140 b is a target of the Rocky Worlds Director’s Discretionary Time Program, a joint effort of JWST and Hubble specifically designed to test whether rocky exoplanets around dwarf stars hold atmospheres. According to Dittmann, the program should be able to confirm or refute the atmosphere within the next four to five years, and probe for carbon dioxide and water once helium has broken the ice. If those follow-ups hold, the planet becomes the most compelling nearby laboratory for atmospheric habitability around a low-mass star.

Reference: Cherubim, C., et al. (2026). Detection of helium escape from the rocky exoplanet LHS 1140 b. Science.

© 2026 SKYCR.ORG | Homer Dávila Gutiérrez, FRAS. All rights reserved. Reproduction in whole or in part without express authorization is prohibited. Original source: Science (2026). DOI: 10.1126/science.aea9708.