LHS 1140b exoplanet shows potential signs of a secondary atmosphere

Astronomers have detected evidence of helium gas escaping from the atmosphere of LHS 1140b, a potentially rocky exoplanet located within its star’s habitable zone. The planet orbits a faint red dwarf star in the constellation Cetus.

The presence of helium is significant because it may indicate a “secondary” atmosphere. Unlike “primary” atmospheres, which are hydrogen-rich and typically lost shortly after a planet forms, secondary atmospheres are thought to be more stable and long-lived. On Earth, such atmospheres are shaped by geology, chemistry, and biological processes.

While previous observations using the James Webb Space Telescope ruled out a hydrogen-rich atmosphere, the detection of helium remains tentative, as a subsequent observation did not detect the gas. If confirmed, studying LHS 1140b could provide insights into how planetary atmospheres evolve and assist in identifying potential signs of life on other worlds.