Astronomy has long held the dream of discovering a second Earth, a planet with a solid surface, comfortable temperatures, and a breathable atmosphere. Now, researchers may have found a promising candidate in the exoplanet LHS 1140 b, which has been detected with escaping helium—a strong indication of an atmosphere.
The Importance of LHS 1140 b
Located about 49 light-years away in the constellation Cetus, LHS 1140 b is classified as a “super-Earth”—1.7 times larger and 5.6 times heavier than our own planet. It orbits a red dwarf star, which is smaller and cooler than our sun, allowing the planet to reside in a habitable zone where liquid water could potentially exist. The study revealing these findings was published in the journal Science on Wednesday.
Helium Detection and Its Implications
Research conducted by an international team, including scientists from Harvard University, discovered a helium signal in September 2024. This was a significant indication that LHS 1140 b possesses an atmosphere, according to co-author Shreyas Vissapragada from the Carnegie Institution. However, in a surprise twist, follow-up observations in 2025 showed that this helium signal had disappeared. For researchers, this wasn’t a failure; rather, it highlighted the dynamic nature of the atmosphere.
Understanding the Atmosphere’s Changes
The loss of helium is attributed to the intense X-ray and UV radiation emitted by the red dwarf star, which can effectively heat the upper atmosphere and lead to the expulsion of lighter elements. This raises intriguing questions: Can planets orbiting such stars retain an atmosphere over billions of years? Given that red dwarfs are the most common type of star in the Milky Way, understanding these atmospheres is essential for future exoplanet research.
Is Life Possible on LHS 1140 b?
Despite the exciting findings, researchers are cautious about declaring LHS 1140 b a potential home for life. Vissapragada warns, “We still don’t know enough about the planet’s lower atmosphere to make statements about its composition, let alone its surface or the presence of liquid water.” The study indicates that helium dominates the upper atmosphere, possibly hiding heavier elements like oxygen and carbon in deeper layers. Some analyses even suggest that LHS 1140 b might be a water world, containing up to 19% of its mass in water.
Future Research Directions
The research team plans to conduct follow-up observations to unravel the mysterious fluctuations in the helium signal. Notably, a neighboring planet in the same system, LHS 1140 c, does not exhibit any helium, indicating it is likely an atmosphere-less world. This contrast makes the findings regarding LHS 1140 b even more significant.
