Alien life? Why the possibility of exoplanet LHS 1140b emitting helium gas is so exciting

This summer, the study of exoplanets orbiting stars beyond our sun has made significant progress, thanks to the detection of helium gas escaping from the atmosphere of LHS 1140b. This exoplanet resides within the habitable zone of a faint red star in the constellation Cetus, and it is a rocky world with the potential to host liquid water on its surface.

Previous observations with the James Webb Space Telescope had already ruled out a hydrogen-rich atmosphere, typical of a "primary" atmosphere that is thought to form around young planets and is lost to space soon after. However, the observed helium hints at the presence of a "secondary" atmosphere, which is more stable and long-lived.

This exciting discovery marks the second time astronomers have detected even a hint of an atmosphere around a remotely Earth-like planet, following the case of Gliese 1214b. While there are uncertainties surrounding the planet's classification as a super-Earth or a mini-Neptune, this observation represents a crucial step forward in the field of atmospheric spectroscopy of potentially habitable worlds.