Astronomers have confirmed for the first time the existence of a rocky planet with an atmosphere that is also located in what is known as the habitable zone.

Located 48 light-years away, the exoplanet (that is, a planet outside our solar system) may be the most similar to Earth that researchers have found. If it’s not a twin, it’s certainly a family member.

Researchers at the Harvard-Smithsonian Center for Astrophysics were able to detect helium signatures around LHS 1140 b, an exoplanet orbiting a cold red dwarf. The previously identified body has a rocky composition and is far enough from its host star to be able to retain liquid water on its surface. The team documented their findings in the journal Science this week.

The presence of an atmosphere is essential for a planet to support life as we know it. On Earth, for example, the atmosphere allows water to remain liquid, rather than boiling or sublimating easily. It also helps maintain a stable climate by regulating the planet’s temperature and reducing the impact of harmful space radiation.

Astronomers searching for habitable planets often look for Goldilocks-type conditions that might be right for life. LHS 1140 b is the first exoplanet to provide strong evidence that it meets the three requirements of being a rocky body located in the habitable zone of a star that also preserves an atmosphere.

The planet was discovered in 2017 and the new findings are based on observations made in 2024 and 2025. To detect an atmosphere 48 light years away, researchers identified helium leaks emanating from the planet. They provide strong evidence that the planet has an atmosphere and, furthermore, that this atmosphere has existed for at least 3 billion years. The researchers first detected the spectral signature of helium and then used physical models to reconstruct how that gas escapes from the atmosphere.

Although the planet is in a habitable zone, that is not proof of life or that its environment resembles that of Earth. In fact, based on the amount of helium escaping, researchers suggest that the atmosphere is very different from our own. The top layer, from which the helium is expelled, is only the most obvious. In the lower layers there could be heavy gases such as nitrogen, carbon dioxide or carbon monoxide.

Importantly, the study confirms the viability of the technique the team used to detect an atmosphere. In the future, scientists will need to observe the planet with more powerful instruments to fully characterize its atmosphere and investigate whether it has surface oceans or other features consistent with habitability.

“Twenty years ago we wondered if other terrestrial-type planets existed,” says Robin Wordsworth, a Harvard professor and one of the authors of the study, in a press release. “Then we learned that they were common and found some in the habitable zone. The next question was whether any of them had managed to maintain an atmosphere. Now we know that at least one has done so.”

This story originally appeared on WIRED in Spanish and has been translated from Spanish.