A recent astronomical study has identified 45 rocky exoplanets orbiting within the habitable zones of their stars, selected from more than 6,000 confirmed exoplanets. These represent prime targets in the ongoing search for conditions that could potentially support alien life.
The research, led by Professor Lisa Kaltenegger of Cornell University and published in the Monthly Notices of the Royal Astronomical Society in March 2026, utilized updated data from the European Space Agency’s Gaia mission and NASA’s Exoplanet Archive. It focused on planets with radii less than about twice that of Earth or masses below roughly five Earth masses—consistent with rocky composition—and positioned in the empirical habitable zone (HZ), where liquid water could exist on the surface under suitable atmospheric conditions.
A more conservative “3D” habitable zone model, which incorporates atmospheric and cloud effects, produces a shorter list of 24 planets. This work marks a transition in exoplanet science toward prioritizing specific targets for in-depth observation.
Notable candidates
The shortlist features several prominent systems valued for their proximity, rocky nature, and observational accessibility.
- Proxima Centauri b: The closest known exoplanet to Earth at 4.2 light-years, orbiting the red dwarf Proxima Centauri in the Alpha Centauri system. It has a minimum mass of about 1.06 Earth masses and orbits in the habitable zone every 11.2 days. It receives roughly 65% of Earth’s stellar irradiation. Its nearness makes it a high-priority target for direct imaging and spectroscopy, though the host star’s activity (flares) poses potential challenges to atmospheric retention.
- TRAPPIST-1 system (approximately 40 light-years away): An ultra-cool red dwarf hosting seven Earth-sized planets, with TRAPPIST-1 d, e, f, and g appearing in or near the habitable zone across analyses. TRAPPIST-1e, for instance, has a radius of about 0.92 Earth radii and receives stellar energy comparable to Earth in some models. The system’s compact layout enables comparative planetology. JWST observations have begun constraining atmospheres, with some inner planets showing signs of possible atmospheric loss due to stellar activity, while others remain candidates for thin atmospheres or surface conditions suitable for liquid water. Frequent transits make them excellent targets for transmission spectroscopy.
- Kepler-186 f (approximately 500–580 light-years away): The first Earth-sized planet discovered in the habitable zone of a star other than the Sun (announced 2014). Orbiting a red dwarf with a radius of about 1.17 Earth radii, it lies toward the outer edge of the habitable zone, receiving roughly one-third of Earth’s insolation. A thicker CO₂-rich atmosphere could potentially maintain surface liquid water.
- LHS 1140 b (about 48–49 light-years away): A super-Earth with a mass of roughly 5.6–6.4 Earth masses and radius of 1.73 Earth radii, orbiting in the conservative habitable zone. It transits its red dwarf host, facilitating atmospheric studies. Recent JWST data support a possible water-world scenario (with a substantial water fraction) and a CO₂/N₂-rich atmosphere, making it one of the stronger nearby candidates.
- TOI-715 b (137 light-years away): A transiting super-Earth (radius ~1.55 Earth radii) in the conservative habitable zone of its red dwarf, discovered by TESS. It serves as an accessible target for further atmospheric characterization.
Other notable entries include planets around quiet red dwarfs such as GJ 1002 b and c, GJ 1061 c and d, and additional Kepler/K2 worlds. Several planets on the list, including TRAPPIST-1e, TOI-715 b, and Proxima Centauri b, receive stellar irradiation similar to modern Earth.
Scientific context and limitations
The empirical habitable zone draws boundaries informed by Venus (inner edge) and Mars (outer edge) in our Solar System, scaled for different stellar types. True habitability hinges on factors beyond orbital distance alone, including atmospheric composition, magnetic fields, water content, geology, and stellar radiation—particularly relevant for the many red dwarf hosts, which are easier to detect but can be active.
No confirmed atmospheres or biosignatures exist for these planets yet. Of the 45, 27 are transiting and thus prioritized for spectroscopy. The catalog guides observations with the James Webb Space Telescope (JWST), the Extremely Large Telescope (ELT), and future missions like the Habitable Worlds Observatory.
This shortlist does not assert the presence of life but identifies the most promising rocky worlds where surface liquid water could exist, offering a practical framework for testing habitability limits in the years ahead. The full analysis appears in the paper by Bohl et al. (2026), with lists expected to evolve as stellar and planetary data improve.
