The Search for Another Earth-Like Planet Just Took a Big Step Forward

Astronomers have confirmed for the first time the existence of a rocky planet with an atmosphere that also happens to be in what's 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 thing to Earth that researchers have come across. If not a twin then certainly a family member.

Researchers at the Harvard-Smithsonian Center for Astrophysics were able to detect signatures of helium around LHS 1140 b, an exoplanet circling a cool 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 in a liquid state, rather than boiling or sublimating easily. It also helps maintain a stable climate by regulating the planet’s temperature and reduces the impact of harmful space radiation.

Astronomers searching for habitable planets typically look for Goldilocks-type conditions that could be just right for life. LHS 1140 b is the first exoplanet to provide solid evidence that it meets all three requirements of being a rocky body located in a star’s habitable zone that also retains an atmosphere.

The planet was discovered in 2017, and the new findings are based on observations taken in 2024 and 2025. To detect an atmosphere from 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.

While the planet is in a habitable zone, that isn't proof of life or that its environment resembles that of Earth. In fact, based on the amount of helium escaping, the researchers suggest that the atmosphere is very different from ours. The upper layer, from which the helium is expelled, is only the most obvious one. 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 for detecting an atmosphere. Moving forward, 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 compatible with habitability.

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