Astronomers Find an Atmosphere on a Nearby Earthlike Planet

Astronomers Confirm Atmosphere on Nearby Earth-like Planet

Researchers have identified an atmosphere surrounding LHS 1140b, a rocky, Earth-like exoplanet located approximately 49 light-years away in the constellation Cetus. The discovery, published in the journal *Science*, marks the first observationally confirmed atmosphere on a rocky planet residing within a star’s habitable zone outside our solar system. The findings suggest that LHS 1140b possesses the essential components to potentially support life: a rocky composition, a temperature capable of maintaining liquid water on its surface, and an atmosphere that shields the surface from harmful stellar radiation while preventing water from escaping into space.

A Milestone in Exoplanet Research

LHS 1140b, discovered in 2017, orbits a small, dim red dwarf star. While the planet is 5.6 times the mass of Earth and 70% larger in radius, it is considered a prime candidate for astrobiology. According to lead author Dr. Collin Cherubim, a postdoctoral fellow at Harvard University, this is the first direct identification of an atmospheric species for any rocky exoplanet. The research team utilized an infrared spectrograph mounted on the Magellan Clay telescope at the Las Campanas Observatory in Chile to observe the planet as it transited its host star. By detecting helium escaping from the planet’s upper atmosphere, scientists confirmed the presence of a gaseous envelope. Because helium is a light element that typically drifts away from small, rocky planets, its detection—and the fact that the planet has likely held its atmosphere for over 3 billion years—indicates that the planet must possess a thicker, multilayered atmosphere that may be replenishing its gas supply.

Context and Planetary Characteristics

The star hosting LHS 1140b is smaller and cooler than our sun, but it releases a significant proportion of its energy as ionizing radiation. Unlike many other red dwarf systems that are prone to violent flares and coronal mass ejections capable of stripping away planetary atmospheres, the star hosting LHS 1140b is described as relatively quiet. Dr. Jason Dittmann, an assistant professor of astronomy at the University of Florida who first discovered the planet in 2016, noted that the age of LHS 1140b previously led many in the scientific community to believe such a world would have lost its atmosphere long ago. The team’s discovery challenges previous assumptions, as LHS 1140b has managed to retain its gaseous layer despite its age. During the study, researchers also observed a second planet in the system, LHS 1140c; however, no atmosphere was detected around that world.

Variability and Future Observations

A notable aspect of the study was the variability of the helium signal. While helium was detected in data captured in 2024, observations conducted in 2025 did not show the same signature. Experts emphasize that this variability does not invalidate the findings.

Implications for the Search for Life

While the discovery significantly advances our understanding of habitable-zone worlds, scientists remain cautious regarding the direct search for life. Despite this, the scientific community views LHS 1140b as a premier laboratory for future study. Researchers plan to use the current model to search for additional rocky planets that may have retained their atmospheres. The next phase of research will focus on determining the full chemical composition of the atmosphere and investigating potential surface features, such as oceans, to better understand if the environment could truly harbor life.

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