LHS 1140 b is leaking helium — the best evidence yet that a habitable-zone world kept its air
For almost a decade, the most closely watched rocky planet in the exoplanet catalogue has been LHS 1140 b: a super-Earth in the habitable zone of a quiet red dwarf about 48 light-years away, in the constellation Cetus. The open question was never whether it exists. We’ve known that since 2017. The question was whether a small planet sitting that close to a red dwarf could hold onto an atmosphere at all. A paper published in Science on July 16 gives the strongest answer yet, and it comes from an unexpected direction: the planet is losing gas. A Harvard-led team caught helium streaming off the top of its atmosphere. That leak, counterintuitively, is the best evidence we have that there’s an atmosphere down there to leak from. ...