Helium escaping from atmosphere of nearby rocky exoplanet in a habitable zone

Astronomers have detected helium escaping from the atmosphere of a rocky exoplanet in the habitable zone of a nearby star, marking the first evidence of an atmosphere on such a world, researchers announced. The findings, published in the journal Science, come from a team led by Collin Cherubim, who completed the work while earning his Ph.D. at Harvard alongside researchers from Carnegie Science and other institutions. The planet, LHS 1140 b, is a super-Earth about 5.6 times Earth's mass and 1.7 times its radius located 48 light-years away. It orbits a red dwarf star every 24.7 days. Researchers used the WINERED spectrograph on the Magellan Clay Telescope in Chile to observe the system in 2024. The spectrum contained the signature of helium escaping into space. A smaller neighboring planet that crossed the star the same night showed no comparable signal. Study co-author Shreyas Vissapragada said the detection was clear evidence of an atmosphere on a habitable-zone exoplanet. Advisor David Charbonneau, who initially doubted the prediction, said the detection was statistically rock solid. When researchers observed the planet again in 2025, they did not detect escaping helium, suggesting atmospheric escape varies over time. Models suggest the atmosphere has likely survived for more than 3 billion years.