Researchers reported the LHS 1140 b exoplanet atmosphere around the rocky world 49 light years away, making it the first observationally confirmed atmosphere around a rocky planet in the habitable zone outside the solar system. Collin Cherubim said it was the first actually observationally confirmed atmosphere on a rocky planet in the habitable zone outside of our solar system.
The study also reported the first direct identification of an atmospheric species for any rocky exoplanet, after data captured in 2024 revealed helium escaping from LHS 1140b into space. Cherubim said, "This is a really exciting discovery because I think it really puts LHS 1140b at the forefront as the best, most promising, exciting laboratory for studying astrobiology and habitability outside of our solar system."
Magellan Clay telescope in Chile
The team observed LHS 1140b as it passed in front of its star using an infrared spectrograph mounted on the Magellan Clay telescope at Las Campanas Observatory in Chile. The star is smaller and dimmer than the Sun, and it releases a greater proportion of its energy as ionising radiation than the Sun.
Jayne Birkby said, "the work was a fantastic discovery." She also said small red dwarf planets are the most common type of star and our best chance for studying nearby rocky exoplanets in their habitable zone.
2024 and 2025 data
The 2024 helium signal did not repeat in 2025 observations, which complicated the first interpretation. The team ruled out contamination from Earth’s atmosphere as an explanation for the helium signal, leaving the change between the two observing years as the unresolved point in the dataset.
LHS 1140b was discovered in 2017, has a mass 5.6 times that of Earth, and has a radius 70% larger than Earth’s radius. The team found no atmosphere around LHS 1140c.
Cherubim said, "So it’s a really exciting place to keep looking, especially to look for signs of life."
