Exoplanet LHS 1140 b Confirmed to Have Atmosphere

An international team of astronomers has detected an atmosphere on the rocky exoplanet LHS 1140 b, located about 48–49 light‑years from Earth. The planet is a super‑Earth with roughly 5.6 times Earth's mass and 1.7 times its radius, orbiting a red dwarf every 24.7 days within the star’s habitable zone where temperatures could allow liquid water.

Using the Magellan Clay telescope at Las Campañas Observatory in Chile, researchers observed the escape of helium from the planet’s upper atmosphere, providing the first clear spectroscopic evidence of an atmosphere on a terrestrial planet in the habitable zone. The findings were published in *Science* and led by Harvard astronomer Collin Cherubim, with contributions from José Antonio Caballero and other U.S. university teams.

Helium was detected in 2024, but follow‑up measurements in 2025 showed a reduced signal, suggesting that the atmosphere may be changing over time. The discovery marks a milestone for exoplanet science, demonstrating that rocky worlds can retain atmospheres and opening new pathways in the search for potentially habitable environments beyond the Solar System.