[photo credit: Carnegie Science]
The prediction rests on a method called astrometry, which detects planets by measuring how their gravity tugs stars sideways across the sky. Astronomers have tried this approach since the 1940s with almost no success—the wobbles are vanishingly small and ground-based telescopes too imprecise. Gaia, operating from space with unprecedented accuracy, changes that calculus. Its fourth data release, scheduled for December 2026, will include the first extensive time-series measurements precise enough to detect giant planets.
Lammers and Princeton professor Joshua N. Winn, a co-investigator on NASA’s planet-hunting TESS mission, estimate the five-year dataset will yield 7,500 ± 2,100 planet discoveries. A full 10-year dataset expected by 2030 could reveal 120,000 ± 22,000 more. Most will be super-Jupiters—gas giants three to 13 times Jupiter’s mass—orbiting their stars at roughly the distance Jupiter orbits the Sun.
“The Gaia mission promises a new beginning for astrometric planet discovery,” the researchers wrote in a paper published last November.
The scale of that promise comes into focus against current tallies. NASA confirmed its 6,000th exoplanet in September 2025, the vast majority found by watching stars dim as planets cross in front of them or wobble toward Earth under gravitational tugs. Astrometry measures a different wobble—the lateral motion across the sky—and can detect planets that other methods miss, particularly those on wider orbits or in systems tilted away from Earth’s line of sight.
Lammers, who studies how planets form and evolve, will present predictions along with warnings about false alarms. Unresolved pairs of binary stars can mimic the signature of planets, though the researchers estimate genuine discoveries will outnumber imposters by a factor of five or more. They have published mock catalogs at github.com/CalebLammers/
Carnegie Observatories has hosted frontier astronomical research for more than a century; it was there that Edwin Hubble confirmed the universe extended far beyond the Milky Way. The institution’s lunch talk series offers informal presentations on current research.
“Gaia’s Exoplanet Potential,” a lunch talk by Princeton PhD student Caleb Lammers, takes place Thursday, February 6, from 12:15 to 1:15 p.m. at the William T. Golden Auditorium, Carnegie Observatories, 813 Santa Barbara Street in Pasadena.
The talk is part of Carnegie Observatories’ informal lunch seminar series; admission details were not listed. A Zoom option is available for remote viewing. For more information, call (626) 577-1122 or visit carnegiescience.edu/caleb-
