When Jason Dittmann first spotted a rocky planet called LHS 1140b in 2016, he had no idea it might still be holding onto an atmosphere. Almost ten years later, a new study reveals something remarkable: this distant world, located 40 light-years away, may be quietly replenishing its helium supply — and scientists think that could mean it has an atmosphere similar to Earth's.
Dittmann, now an Assistant Professor of Astronomy at the University of Florida, discovered the planet using ground-based telescopes that watch stars for brief flickers of dimming light. Those flickers can signal a planet passing in front of its star, like a tiny eclipse. The tricky part? Earth's own weather creates similar flickers. So Dittmann trained a machine learning algorithm to tell the difference between signals from clouds and signals from distant worlds. That algorithm helped him find LHS 1140b.
Since the planet's orbit only allows astronomers to observe it a few times each year, every chance to study it counts. When Dittmann requested X-ray data from the planet's star, he was thinking ahead. Years later, that data became essential for understanding what the Magellan Clay telescope in Chile would reveal: helium gas escaping from the planet.
Helium escaping happens on Earth too, so that part isn't unusual. What surprised researchers was that LHS 1140b still had helium left to lose. The planet is old enough that similar rocky worlds have already lost their atmospheres entirely. If LHS 1140b wasn't making new helium, it should have run out long ago. The fact that it hasn't suggests something is replenishing the supply — possibly a hidden atmosphere slowly leaking into space.
"We were getting to the point in the field where maybe all of these planets don't have an atmosphere, and we need to look at ones around sun-like stars instead of smaller stars," Dittmann said. "And then finally here is actually one with an atmosphere, and it happens to be the one that I had spent so many hours working on."
The team published their findings in the journal Science, marking the first time researchers have spotted a rocky, Earth-like planet that might still have an atmosphere. Next, the James Webb Space Telescope will take a closer look. As one of the targets under the Rocky Worlds program — a project dedicated to finding atmospheres on small exoplanets orbiting small stars — it will search for water vapor in the coming years. If water shows up, it could confirm that LHS 1140b has a stable, ongoing atmosphere that could potentially support life.
Scientists expect answers within four to five years. For Dittmann, who spent years building the tools to find this planet, the wait is already familiar territory.