Discovery of an Atmosphere on LHS 1140 b
For the first time, astronomers have identified an atmosphere on a rocky planet located in the habitable zone of another star. The planet, designated LHS 1140 b, has a mass over five times that of Earth and a radius 1.7 times larger. Situated roughly 50 light-years away, it orbits a red dwarf star whose mass and size are about one-fifth those of the Sun.
The research team found that the planet's atmosphere is composed of helium, which is escaping into space at a rate of hundreds of thousands of kilograms per second. This helium is heated to over 4,700 degrees Celsius. This breakthrough was made possible using the WINERED spectrograph at the Las Campanas Observatory in Chile's Atacama Desert, during observations conducted on a September night in 2024. However, during follow-up observations in 2025, researchers did not detect any helium outflow from the planet.
Colin Cherubim, one of the scientists, stated: 'This is the first time anyone has detected an atmosphere on a rocky planet in the habitable zone of another star.'
The atmosphere of LHS 1140 b has been maintained for over 3 billion years. The planet receives 42 percent of the energy from its star that Earth receives from the Sun. Although it has experienced higher levels of X-ray and ultraviolet radiation—which typically erodes rocky planetary atmospheres—it has managed to retain some helium, likely accumulated during its formation. Cherubim noted: 'It has shown that planets in the perfect spot can lose hydrogen and retain helium, creating a helium-dominated atmosphere: planets I call "helium worlds."'
Research Prospects
This discovery provides the strongest evidence to date of worlds beyond our solar system with Earth-like conditions. LHS 1140 b is consistent with a rocky, terrestrial composition and a low-density component, such as a thin atmosphere and possibly some water. The next challenge for researchers is to study the planet to determine whether it has oceans or other features conducive to life.
The detection of an atmosphere on LHS 1140 b marks a significant step in exoplanet research, as it confirms the possibility of conditions that could support life outside our solar system. Studying this planet could offer new insights into the formation and evolution of atmospheres on rocky worlds, as well as address questions about the presence of water and other elements essential for life. This finding may stimulate further exploration in the search for potentially habitable planets in our galaxy.
This remarkable finding adds to the growing body of evidence about potentially habitable worlds beyond our solar system. For instance, researchers recently discovered a Super-Earth located just 25 light-years away, further highlighting the diversity of planetary systems and the intriguing possibilities they present for future exploration.