LHS 1140 b: First rocky exoplanet in habitable zone found with an atmosphere

Astronomers led by Collin Cherubim of Harvard University have detected the first atmosphere on a rocky, Earth‑like planet located in the habitable zone of another star. The planet, LHS 1140 b, orbits a red dwarf about 48 light‑years from Earth and has a mass ≈ 5.6 × Earth’s and a radius ≈ 1.7 × Earth’s. Using the WINERED infrared spectrograph on the Magellan Clay telescope at Las Campanas Observatory in Chile, researchers observed helium escaping from the planet’s upper atmosphere during a rare transit alignment in 2024. The detection, published in *Science*, marks the first direct confirmation of an atmosphere on a rocky exoplanet inside its star’s Goldilocks zone. Follow‑up observations in 2025 showed the helium signal had weakened, suggesting variable atmospheric escape. The finding provides the strongest evidence yet that some super‑Earths can retain atmospheres, an essential ingredient for habitability, and opens new avenues for studying potential biosignatures on distant worlds.