Astronomers confirmed for the first time there is a rocky planet with an atmosphere that is also in the so-called habitable zone.
Located 48 light-years away, an exoplanet – a planet outside our solar system – may be the most Earth-like thing researchers have ever encountered. If not a twin, then definitely a family member.
Scientists at the Harvard-Smithsonian Center for Astrophysics have detected helium signatures around LHS 1140 b, an exoplanet orbiting a frosty red dwarf star. The previously identified body has rocky composition and is located far enough from its host star to retain liquid water on its surface. The team documented their findings in a journal Science this week.
The presence of atmosphere it is imperative for the planet to support life as we know it. On Earth, for example, the atmosphere allows water to remain liquid rather than easily boiling or sublimating. It also helps maintain a stable climate by regulating the planet’s temperature and limiting the impact of harmful cosmic radiation.
Astronomers searching for habitable planets typically look for Goldilocks-type conditions that might be suitable for life. LHS 1140 b is the first exoplanet to provide solid evidence that it meets all three requirements for being a rocky body located in the habitable zone of a star that also retains an atmosphere.
The planet was discovered in 2017, and the modern findings are based on observations made in 2024 and 2025. To detect the atmosphere from 48 light-years away, researchers identified helium leaks emanating from the planet. They provide sturdy evidence that the planet has an atmosphere and, furthermore, that this atmosphere has existed for at least 3 billion years. Scientists first detected the spectral signature of helium, then used physical models to reconstruct how the gas escapes from the atmosphere.
Although the planet is in the habitable zone, this is not evidence that life exists or that its environment is Earth-like. In fact, based on the amount of escaping helium, scientists suggest that the atmosphere is very different from ours. The top layer from which helium is ejected is only the most obvious. The lower layers may contain massive gases such as nitrogen, carbon dioxide or carbon monoxide.
Importantly, the study confirms the feasibility of the team’s atmospheric sensing technique. In the future, scientists will need to observe the planet with more powerful instruments to fully characterize its atmosphere and investigate whether this is happening has surface oceans or other characteristics consistent with habitability.
“Twenty years ago, we wondered whether other terrestrial planets existed at all,” says Robin Wordsworth, a Harvard professor and one of the study’s authors, in a press release. “Then we found out they were common and found several in the habitable zone. The next question was whether any of them managed to maintain the atmosphere. Now we know at least one managed to do so.”
This story originally appeared on WIRED in Spanish and was translated from Spanish.