Overview
- A paper published in Science on Thursday reports that observations in 2024 with the WINERED spectrograph on the Magellan Clay telescope found excess helium absorption during a transit of LHS 1140 b, which the authors interpret as an escaping upper atmosphere.
- The signal matches a preexisting theoretical model that predicted helium‑rich upper layers can form on some rocky habitable‑zone planets through long‑term loss of lighter hydrogen.
- Helium absorption traces the planet’s extended upper atmosphere rather than surface gases, so the detection shows an atmosphere exists but does not yet reveal the lower‑atmosphere composition or surface conditions.
- Follow‑up observations taken in 2025 did not reproduce the helium signature, leaving open the possibilities of time variability, observational limits, or a false positive and prompting the team to reanalyse the data.
- Researchers say confirming persistence and measuring composition will require independent detections from space telescopes and more ground observations, and they note the host star’s relatively quiet nature makes LHS 1140 b a high‑priority target for habitability studies.