Cornell University astronomers have narrowed the search for extraterrestrial life to 45 rocky planets, publishing what amounts to a prioritized target list for the world’s most powerful telescopes. The study, released March 19 in the Monthly Notices of the Royal Astronomical Society, draws on fresh stellar data from ESA’s Gaia mission and the NASA Exoplanet Archive to build the most current catalog of rocky worlds sitting in the so-called habitable zone around their stars.
The timing is hard to ignore. Hollywood just released Project Hail Mary, based on Andy Weir’s novel, in which Ryan Gosling plays an astronaut who travels to a distant star system searching for life that might save Earth. Lisa Kaltenegger, professor of astronomy and director of the Carl Sagan Institute at Cornell, put it plainly: “Our paper reveals where you should travel to find life if we ever built a Hail Mary spacecraft.”
Of the more than 6,000 exoplanets confirmed to date, the vast majority are gas giants, lava worlds, or frozen rocks with no plausible shot at life. The new catalog cuts through that noise. The team identified 45 worlds inside the empirical habitable zone — the range of distances from a star where liquid water could sit on a planet’s surface — and a tighter group of 24 inside a more conservative 3D habitable zone that applies stricter limits on how much heat a planet can absorb before conditions collapse.
The list includes some well-known names. Proxima Centauri b, orbiting our nearest stellar neighbor just 4.2 light-years away, makes the cut. So does TRAPPIST-1e, an Earth-sized planet where the James Webb Space Telescope has detected tentative signs of methane in recent observations. Kepler-186f, the first Earth-size world ever found in a habitable zone, is on the list alongside TOI-715b, a planet 1.55 times Earth’s width circling a red dwarf star 137 light-years away.
What makes a planet rank higher on the list is how closely its light environment mirrors Earth’s. The worlds receiving stellar flux most similar to what the Sun delivers to Earth include TRAPPIST-1e, TOI-715b, Kepler-442b, Wolf 1069b, and Proxima Centauri b. Those planets are receiving roughly the same amount of energy from their stars that Earth does from the Sun — a baseline condition scientists treat as a meaningful starting point.
The catalog also targets planets near the edges of the habitable zone on purpose. Kaltenegger and her team want to test where habitability actually breaks down, not just where models predict it should. “While the idea of the habitable zone has been developed since the 1970s, new observations will be critical in establishing whether certain assumptions need adapting,” Kaltenegger said. Planets with unusually elliptical orbits that carry them in and out of the habitable zone are included specifically to test whether intermittent conditions can still support life.
The research was a collaboration between Kaltenegger and three Cornell undergraduates: Abigail Bohl, Lucas Lawrence, and Gillis Lowry. The team pulled updated stellar data from Gaia’s third data release, which provided sharper measurements of the host stars — crucial, since the habitable zone boundaries depend almost entirely on knowing how bright and hot a star actually is.
The catalog is designed to feed directly into observing schedules for current and near-future instruments. The James Webb Space Telescope is already studying several of these targets. The Nancy Grace Roman Space Telescope and the Extremely Large Telescope, both expected to come online in the next few years, will add atmospheric observation power that current tools can’t match. The Habitable Worlds Observatory, a NASA concept still in development, is specifically designed to image Earth-like planets around Sun-like stars.
Kaltenegger framed the broader challenge with characteristic optimism: “As Project Hail Mary so beautifully illustrates, life might be much more versatile than we currently imagine.” Whether TRAPPIST-1e’s methane hints or Proxima Centauri b’s tantalizing proximity will eventually yield something definitive remains the question these telescopes were built to answer.
