# Cambridge Study Finds All Four Planets Around Barnard's Star Are Uninhabitable

*2026-07-21 10:01 UTC · Science · 1 min read*

> A Cambridge-led study finds all four rocky planets orbiting Barnard's Star are tidally locked, atmosphere-less, and "extremely uninhabitable."

Astronomers led by Xander Byrne at the University of Cambridge's Institute of Astronomy have published the most detailed profile yet of the four planets orbiting Barnard's Star, humanity's second-closest stellar neighbor just under six light-years away. The sub-Earth-sized rocky worlds, discovered in 2025, sit in a size class larger than Mars but smaller than Earth or Venus, with no equivalent in our own solar system.

The study, published in Monthly Notices of the Royal Astronomical Society, finds the planets' interiors are dominated by magnesium-rich periclase, a mineral that stores little water. Combined with tidal locking and orbits roughly ten times tighter than Mercury's around the Sun, the researchers conclude any atmosphere would have dissipated within 2 billion years, leaving permanent day and night sides with no chance of hosting life.

An orbital resonance locking the inner three planets in a 9:12:16 ratio helps keep the tightly packed system gravitationally stable. "These planets were always going to be hostile because they're really close to their star," Byrne said. The findings will help refine target lists for upcoming missions like ESA's PLATO, designed to hunt for more Earth-like worlds elsewhere.

## Sources

- [phys.org](https://phys.org/news/2026-07-astronomers-nearby-planets-small-strange.html)
- [universetoday.com](https://www.universetoday.com/articles/astronomers-determine-that-exoplanets-around-barnards-star-are-extremely-uninhabitable)

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Česká verze: https://techtools.cz/tools/news/clanek/2118-studie-z-cambridge-vsechny-ctyri-planety-u-barnardovy-hvezdy-jsou-neobyvatelne