Astronomers have caught helium leaking from the upper atmosphere of a rocky super-Earth 48 light-years away. The detection marks the first time anyone has confirmed an atmosphere on a planet of this type sitting in the habitable zone of its star.
LHS 1140 b orbits a small, cool red dwarf. Liquid water could exist on its surface. Previous attempts to pin down its atmosphere had produced only hints. Now the evidence is in.
The breakthrough came from transit spectroscopy observations made with the Magellan Clay telescope at Las Campanas Observatory in Chile. On 23 September 2024 the telescope captured a rare alignment of transits involving another planet in the system. A follow-up observation in 2025 recorded no helium absorption, showing that the escape rate varies and is probably tied to stellar activity.
Helium-dominated upper layer
The upper atmosphere appears dominated by helium and largely free of hydrogen. Models suggest heavier molecules such as water or nitrogen could remain at lower altitudes. The neighbouring planet, LHS 1140 c, showed no atmospheric signature at all.
This is the first time anyone has found an atmosphere on a rocky planet in the habitable zone of another star.
Collin Cherubim, lead author and recent PhD graduate from Harvard University, put the result in plain terms. An atmosphere, he noted, is essential for a planet to support life as we know it.
The study appeared in the journal Science on 16 July 2026. It rests on careful, repeatable observation rather than optimistic extrapolation. Years of prior work on LHS 1140 b had already ruled out a hydrogen-dominated atmosphere and turned up tentative signs of nitrogen. The new helium detection confirms the planet has held on to some atmosphere despite billions of years of bombardment from its star's radiation.
