Astronomers find the strongest evidence yet of a rocky planet beyond us Solar system has managed to maintain an atmosphere – a vital component of life as we know it.
This discovery is the first time that scientists have detected the atmosphere around an orbiting rocky planet. habitable area of another star, the region around the star where temperatures can allow liquid water to exist on the surface of a planet. The findings, published July 16 in the journal Science, That could help astronomers narrow down the search for potentially habitable worlds beyond our cosmic backyard.
“It’s absolutely exciting,” Edward Schwittermanan associate professor of astrobiology at the University of California, Riverside, who was not involved in the study, told Live Science in an email. “We are getting closer to studying world atmospheres that could potentially harbor life, with evidence of that life embedded in their observable spectra.”
planet, known as LHS 1140Bis about 48 light years from Earth and is in a small, cool orbit Red dwarf star. About 5.6 times the mass of Earth, the exoplanet is classified as super earth: a rocky planet that is larger than our planet but much smaller than gas giants like Neptune.
It receives less than half the amount of sunlight that Earth does, leading to an estimated surface temperature of around minus 53 degrees Fahrenheit (minus 47 degrees Celsius), according to previous estimates that did not account for the atmosphere. This makes the planet cooler, but astronomers consider this limit potentially habitable.
cosmic gas leak
Scientists have discovered thousands exoplanets Over the past few decades, including many rocky worlds. but determination Do those planets have atmospheres? has proven far more difficult, because the atmospheres around rocky planets are incredibly thin compared to giant planets, making them much harder to detect across vast cosmic distances.
Instead of searching for the atmosphere directly, the researchers behind the new study discovered a subtle clue that it existed: a leak of helium gas into space. Using the Vinard spectrograph on the Magellan Clay Telescope in Chile, the team watched as LHS 1140b passed in front of its star and allowed a sliver of the star’s light to filter through the planet’s atmosphere on its way to Earth. As this happened, the team looked for a small dip in the star’s light at the exact wavelength of infrared light that the helium blocks – a telltale sign that gas was flowing away from the planet and into space.
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The prediction was based entirely on a mathematical model that had never been confirmed for a rocky planet. However, in September 2024, the team caught LHS 1140 b and a smaller, hotter neighboring planet, LHS 1140CThey transit their stars on the same night, less than 40 minutes apart. The researchers detected a clear helium signal from LHS 1140 b, while LHS 1140 c showed none.
Concept art from NASA depicts LHS 1140 b as a rocky super-Earth – a type of potentially habitable planet similar to our planet.
(Image credit: NASA)
The paradox matters: LHS 1140 c orbits much closer to its star than LHS 1140 b and receives about five times the radiation, yet it is smaller and less gravitationally bound – conditions that should make any ejected gas easier, not harder, to detect. Finding nothing there suggests that LHS 1140 c’s atmosphere was removed long ago, while LHS 1140 b, sitting away in cool, calm conditions, has managed to retain its own.
The discovery addresses a question astronomers have been searching for answers to for decades.
“Twenty years ago we wondered whether other terrestrial-type planets existed,” said the study’s co-author. robin wordsworthProfessor of Earth and Planetary Sciences at Harvard said in a statement. “Then we discovered 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 at least one has.”
One step forward in search of life
The discovery is particularly noteworthy because red dwarf stars like LHS 1140 can bombard nearby planets with high-energy radiation that is capable of destroying atmospheres over time. Based on the star’s estimated age of at least 3.1 billion years, researchers say the atmosphere of LHS 1140 b has likely persisted despite that bombardment, which suggests that some rocky planets around these typical stars may hang on to their atmospheres far longer than they once did.
But researchers caution that the detection of helium does not mean the planet is inhabited – or even that it is habitable. The observations reveal only the planet’s thin upper atmosphere, not its entire composition. Scientists still don’t know whether LHS 1140 b has oxygen, carbon dioxide, water vapor or other gases that might make its surface more Earth-like and favorable for life.
Instead, the discovery opens a new way to study distant rocky worlds.
“The study shows that, at least in some cases, we will be able to begin to characterize the environments of potentially habitable planets,” Schwieterman said. “If only rocky planets orbiting Sun-like stars retain atmospheres, we may have to wait one to two decades for launch Habitable Worlds Observatory Searching for biosignatures on rocky planets. I’m definitely excited about what’s next!”
Future observations will aim to determine what the remaining atmosphere of LHS 1140 b is composed of and investigate whether it may contain oceans or other habitable features.
Cherubin, C., Visapragada, S., Cunningham, T., Meech, A.G., Charbonneau, D., Wordsworth, R., Householder, A., Teske, J., dos Santos, L., Wallach, N., Misner, W., Lin, Z., McWilliam, A., Zhang, M., Dittman, J., Lopez-Morales, M. (2026). Venting helium from the atmosphere of a terrestrial planet into a nearby habitable zone. Science, https://www.science.org/doi/10.1126/science.aea9708