Confirmed Interstellar Objects
The objects whose strongly hyperbolic orbits unambiguously establish an origin beyond the Solar System, each with an IAU interstellar designation: 1I/ʻOumuamua, 2I/Borisov, and 3I/ATLAS.
- 1I/ʻOumuamuaConfirmed interstellar
The first confirmed interstellar object, detected in October 2017 on its way out of the Solar System. Its strongly hyperbolic orbit (eccentricity about 1.2) showed it was never bound to the Sun. It displayed no visible coma, is highly elongated, and showed a slight non-gravitational acceleration — features that drew wide attention, though the scientific consensus is that it is a natural body.
- Trajectory
- Hyperbolic (e ≈ 1.20) — unbound
- Discovered
- 2017-10-19
- 2I/BorisovConfirmed interstellar
The second confirmed interstellar object and the first that was unmistakably a comet, discovered in August 2019 by amateur astronomer Gennadiy Borisov. Its eccentricity of about 3.4 made its interstellar origin certain. Unlike 1I/ʻOumuamua it showed an active dust coma and tail, letting astronomers study the chemistry of a comet formed around another star; it proved unusually rich in carbon monoxide.
- Trajectory
- Hyperbolic (e ≈ 3.36) — unbound
- Discovered
- 2019-08-30
- 3I/ATLASConfirmed interstellar
The third confirmed interstellar object, discovered on 1 July 2025 by the ATLAS survey in Chile. Its orbit is the most strongly hyperbolic of the three found so far, with an eccentricity of roughly 6, and it showed cometary activity as it passed through the inner Solar System in late 2025. Some physical parameters remain preliminary, but its interstellar origin is established by the trajectory.
- Trajectory
- Hyperbolic (e ≈ 6.1) — the most strongly hyperbolic yet found
- Discovered
- 2025-07-01