A faint stream of helium escaping from a distant rocky world has revealed something astronomers had never clearly detected before: an atmosphere around an Earth-like planet in another star’s habitable zone. “This is the first time anyone has found an atmosphere on a rocky planet in the habitable zone of another star.” Around LHS 1140 b, however, the instrument detected escaping helium, providing evidence that the rocky world still holds an atmosphere. Astronomers estimate that the atmosphere surrounding LHS 1140 b has endured for more than three billion years, making the planet an important candidate for further study. Cherubim hopes to determine the atmosphere’s complete chemical makeup and eventually examine whether LHS 1140 b has surface oceans or other features associated with habitability.