For the First Time, Astronomers Confirm an Atmosphere on a Rocky World in Another Star's Habitable Zone

What Astronomers Confirmed

A team led by planetary scientist Collin Cherubim (Harvard University / University of Chicago) detected helium escaping from LHS 1140b using the Magellan Clay telescope in Chile . The findings, published in the journal Science, show that the planet is actively replenishing its helium, meaning it retains a stable atmosphere rather than being a barren, airless rock .

"This is the first actually observationally confirmed atmosphere on a rocky planet in the habitable zone outside of our solar system," said Cherubim .

The Planet's Key Characteristics

• Type: Super-Earth (rocky, terrestrial)
• Distance: Approximately 48 light-years from Earth
• Size: About 1.7 times Earth's diameter and 5.6 times Earth's mass
• Star: Orbits a red dwarf star (LHS 1140) that is about 5 billion years old and has only 15% the mass of our Sun
• Orbit: Crosses in front of its star once every 24.7 days
• Location: Within the habitable zone — the region where temperatures allow liquid water to exist on the surface

Why This Discovery Is Groundbreaking

First of its kind: Until now, astronomers had detected atmospheres only on large gas giants or planets outside the habitable zone. LHS 1140b is the first rocky (terrestrial) planet in the habitable zone with a confirmed atmosphere .

The three essential ingredients: For life as we know it, a planet needs to be rocky, have the right temperature for liquid water, and possess an atmosphere. LHS 1140b is now the only known exoplanet with all three . As Cherubim put it, "At this stage, we have no proof of life existing on this planet. However, we believe that all the crucial and fundamental components are present" .

Top target for finding life: This combination makes LHS 1140b the single best-known target for astrobiology. Future observations with the James Webb Space Telescope (JWST) can search for biosignature gases — such as oxygen, methane, or water vapor — in that atmosphere .

Implications for other worlds: Finding that a nearby rocky world in the habitable zone can hold onto its atmosphere "reinforces the idea that there exists a population of worlds similar to our own with the properties necessary to sustain life" .

The Road to Discovery

LHS 1140b was first discovered in 2017 using the transit method by the MEarth project, which monitors nearby red dwarf stars for periodic dips in brightness caused by orbiting planets . Early observations suggested the planet might have retained its atmosphere , but the helium detection in 2026 provided the first direct, observational confirmation .

Previous work with JWST in 2024 had already ruled out a hydrogen-rich atmosphere for LHS 1140b, pointing instead to a denser atmosphere possibly composed of nitrogen, water vapor, and carbon dioxide . The new helium detection confirms the presence of an atmosphere and shows it is stable over time .

What Comes Next

The confirmation of an atmosphere on LHS 1140b opens a new chapter in exoplanet science. With the James Webb Space Telescope, astronomers can now attempt to identify the specific gases present — potentially detecting chemical signatures associated with biological activity . LHS 1140b also exhibits unique features: some scientists have proposed it could be an "eyeball planet" — a world with a permanent liquid ocean on one side and ice on the other .

Whether or not LHS 1140b hosts life, its confirmed atmosphere proves that habitable-zone rocky planets can hold onto the conditions necessary for life — a discovery that reshapes our understanding of how common Earth-like worlds may be in the galaxy.