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Loading contentThe International Astronomical Union's clearinghouse for the astrometry, orbits, and designations of small Solar-System bodies — and of interstellar objects, to which it assigns the special "I" (interstellar) designations such as 1I, 2I, and 3I. It is operated under the auspices of the IAU.
organization:minor-planet-centerDataset membership
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Scientific entity. See the evidence framework and authority dashboard.
How Minor Planet Center connects across Asteria Star — scientific, cultural, and astrological links are kept separate.
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.
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.
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.
A long-period comet that a close encounter with Jupiter in 1980 flung onto a clearly hyperbolic orbit (eccentricity about 1.06). It is now leaving the Solar System, but — unlike a true interstellar object — it formed here; the hyperbolic orbit is the result of a planetary slingshot, not an origin around another star.
A near-parabolic long-period comet from the Oort cloud, famous for disintegrating completely near perihelion in July 2000 — one of the best-observed comet break-ups. Its orbit was close to the parabolic boundary (eccentricity near 1), the hallmark of a first-time visitor from the distant Solar System, not from interstellar space.
A long-period comet discovered by Andrea Boattini through the Mount Lemmon Survey, on a near-parabolic orbit with an eccentricity extremely close to 1. Like the other long-period comets here it is a distant Solar-System visitor, not an interstellar object: its original orbit is bound and it is not being ejected from the Solar System — the tiny excess over a parabola is an epoch-dependent, perturbed value.
A dynamically new, near-parabolic long-period comet discovered by Pan-STARRS in 2017 and notable for showing activity at a record distance — a coma was detected beyond Saturn's orbit, on the comet's first passage in from the Oort cloud. Its near-parabolic orbit marks it as a distant Solar-System visitor, not an interstellar object.
A newly-found object's observations are reported to the Minor Planet Center, which links them into a single orbit. The more observations over a longer arc, the more precisely the future path is known.
The IAU's clearing house for asteroid and comet observations, designations, and orbits, including near-Earth-object close approaches. Modelled as a real provider with an honest status; no close-approach data is shown until it is connected.
The American Association of Variable Star Observers — for more than a century, the organisation that gathers variable-star observations from amateurs worldwide into a single database that professional astronomers draw on. The model for how amateur and professional astronomy work together.
The Agência Espacial Brasileira is the civilian agency responsible for Brazil's space programme.
The Association of Lunar and Planetary Observers, which coordinates amateur observation of the Moon, the planets, comets, and asteroids — organising observing programmes and archiving the results so that amateur monitoring of the Solar System adds up to something lasting.
Arianespace is a European launch service provider that markets and operates launches of the Ariane family of rockets from the Guiana Space Centre.
The Agenzia Spaziale Italiana is Italy's national space agency, a significant contributor to ESA and to international planetary science missions.
A commercial operator of a low-Earth-orbit constellation for rapid-revisit Earth imaging.
Facts on this topic will be cited from these primary and reference sources.
Official naming, definitions, constellation boundaries, and astronomical nomenclature.
Designations and orbits of asteroids, comets, and minor bodies.