For the first time in human history, astronomers have confirmed an atmosphere surrounding a rocky, Earth-like planet orbiting within the habitable zone of a distant star. The discovery, published in the journal Science and led by Dr. Collin Cherubim of Harvard University, marks a watershed moment in the decades-long search for worlds that could support life beyond our solar system.
The planet, designated LHS 1140 b, sits 48 light-years from Earth. It orbits a red dwarf star roughly one-third the size of our Sun and significantly cooler. While the atmosphere detected so far consists primarily of helium (a gas that cannot sustain life as we know it), the very existence of any atmosphere on a rocky world in the habitable zone challenges long-held assumptions about planetary survival around volatile red dwarf stars.
"This is the first time anyone has found an atmosphere on a rocky planet in the habitable zone of another star," Cherubim told the BBC. "It feels kind of surreal."
More than 6,000 exoplanets have been discovered since the first confirmation over 30 years ago. Hundreds of those orbit in the habitable zone (also called the Goldilocks zone) of their parent stars, where temperatures could theoretically allow liquid water to exist on a planet's surface. But of those, only a few dozen are rocky like Earth. And until now, none of them had been confirmed to have an atmosphere.
This is what makes LHS 1140 b different. It is the first rocky exoplanet in the habitable zone with a directly detected atmosphere. That alone rewrites the playbook for exoplanetary science.
The Long Road to an Atmosphere
LHS 1140 b was originally discovered in 2017 by a team led by astronomer Jason Dittmann, who is also a co-author on this new study. For nearly a decade, the planet sat among thousands of known exoplanets, notable but unremarkable. It was rocky. It was in the right temperature range. But no one could confirm the existence of an atmosphere around it.
That changed when Cherubim developed a planetary evolution model from first principles during his Ph.D. at Harvard. The model made a specific prediction: LHS 1140 b likely retained a detectable atmosphere despite its punishing stellar environment. The team turned the James Webb Space Telescope and ground-based observatories toward the planet and looked for the telltale spectroscopic signatures of gas surrounding the world as it transited its star.
They found helium. Specifically, they detected it in the planet's upper atmosphere. While helium alone is no sign of habitability, its presence proves that the planet has managed to hold onto a gaseous envelope over billions of years. That is a significant finding in its own right.
"This discovery is a big deal because it's showing that at least this rocky planet has retained an atmosphere over billions of years," Cherubim said. "It's a bona fide, robust way of saying yes, atmospheres can survive on rocky exoplanets."
Red dwarf stars, the most common type of star in the galaxy, are notoriously hostile to planetary atmospheres. They emit powerful solar flares and coronal mass ejections, especially in their younger years, that can strip the gaseous envelopes from nearby planets. LHS 1140's red dwarf is roughly 6 billion years old, a few billion years past the age when these stars begin to calm down. The team believes the planet's atmosphere, while slowly leaking helium into space (a process that also happens on Earth), is stable enough to persist.
What Makes a Planet Habitable?
The habitability puzzle has several pieces. A planet must be the right distance from its star (not so close that water boils away and not so far that it freezes solid). It must be rocky, with a solid surface where liquid water could pool. It needs an atmosphere to regulate temperature and shield the surface from radiation. And it needs water itself.
LHS 1140 b checks several of these boxes. It is rocky, with an iron core, according to Cherubim. Its position in the habitable zone means surface temperatures could support liquid water, provided the planet has enough greenhouse effect from its atmosphere. And now, the atmosphere has been confirmed directly, raising the possibility that other gases (including those more relevant to life) may exist in lower atmospheric layers where current instruments have not yet peered.
"If it has some amount of atmosphere that can provide a bit of a greenhouse effect, which we know that it does now, it will very likely be what we consider to be habitable conditions on Earth, and conditions that would likely support liquid water," Dittmann told Space.com.
Dr. David Charbonneau, also of Harvard, emphasized the philosophical weight of the finding. "People are generally interested in the big questions: Are we alone? Is there life beyond the Earth or beyond our solar system? To that end, this study reveals the first atmosphere discovered on a rocky planet in the habitable zone of a star outside of our solar system."
It is important to note what this discovery is not. It is not evidence of life. The researchers are careful to state that they have found helium, not biosignature gases like oxygen, methane, or dimethyl sulphide. But the detection of an atmosphere at all on a planet with conditions broadly similar to early Earth is a critical proof of concept. If one such planet has an atmosphere, others almost certainly do too.
The Broader Search for Life
LHS 1140 b is far from the only world keeping astronomers up at night. The exoplanet K2-18b, a sub-Neptune with a possible water-rich interior, made headlines when scientists detected hints of dimethyl sulphide (a gas produced by marine life on Earth). But a NASA-led reanalysis in 2025 found the signal too weak to confirm and showed that the gas could form through non-biological processes.
The seven rocky planets of the TRAPPIST-1 system remain some of the most tantalizing targets in the galaxy. However, results have been mixed: the James Webb Space Telescope ruled out an Earth-like atmosphere on TRAPPIST-1d, while data on TRAPPIST-1e remains frustratingly inconclusive.
Against this backdrop, LHS 1140 b stands out not just for what it is, but for what it promises. If rocky planets in the habitable zone can hold onto atmospheres, it dramatically increases the number of potentially habitable worlds in the galaxy. Red dwarfs are the most common type of star, so if their planets can retain atmospheres, the universe becomes far more crowded with worlds worth investigating.
The next step is clear: astronomers must push their instruments to detect other gases in LHS 1140 b's lower atmosphere. The James Webb Space Telescope, alongside next-generation ground-based observatories like the Extremely Large Telescope (ELT) currently under construction in Chile, should be able to search for water vapor, carbon dioxide, and methane in the years ahead. If those gases are found, the conversation shifts from whether the planet could support life to whether it already does.
For now, the discovery of an atmosphere on LHS 1140 b is a historic milestone. It proves that Earth-like worlds with atmospheres are not a theoretical possibility but a measurable reality. The generation of scientists who grew up wondering whether there are other worlds like ours finally has an answer: yes, there are. And we have just begun to study them.
