The Gaia mission’s high‑precision astrometry has enabled astronomers to trace stellar motions around the Sun with unprecedented detail. Using this data, senior scientist Nathan Kaib of the Planetary Science Institute and collaborator Sean Raymond of Université de Bordeaux examined a particularly close stellar flyby.
Gravitational perturbation triggers comet influx
Their analysis indicates that a star passing relatively near the Solar System a few million years ago exerted enough gravity to disturb the Oort cloud. This disturbance ejected countless icy bodies from their stable, distant orbits and set them on trajectories toward the inner Solar System.
The team estimates that the encounter caused a sudden surge in comet production, an effect that continues to be felt. The displaced objects remain a source of long‑period comets that intermittently visit Earth’s neighborhood.
Findings are being presented at the American Astronomical Society Division on Dynamical Astronomy meeting, offering new insight into how external gravitational forces shape the long‑term dynamics of our planetary system.
The study highlights the broader value of missions like Gaia, which not only map the Milky Way’s structure but also reveal direct influences on Earth’s orbital environment and potential comet‑impact hazards.