3I/ATLAS
ILLUSTRATION FROM PERIHELION 1.36 AU · ECCENTRICITY 6.141
OVERVIEW
] COMET3I/ATLAS is a hyperbolic comet. Its orbit does not close: it passes within 1.35648 of the Sun once and never returns. Other catalogues list it as 2025 N1 and C/2025 N1 (ATLAS). It was discovered in 2025.
The third interstellar visitor, picked up by a survey telescope in July 2025. It arrived faster than either of the two before it and on a path tilted almost exactly against the plane of the planets, passing closer to the Sun than Mars ever gets.
- WHAT IT IS
- Hyperbolic comet
OBSERVING
] FROM WHERE YOU AREWhat it takes to see 3I/ATLAS for yourself. Everything in this part of the page is worked out for a real horizon, a real night and the equipment you say you have.
CATALOG DATA
] 11 FIELDSThe raw catalogue values, as the source published them, with the error bars where one was published — sorted by what each set of figures is about rather than by the order they happened to be stored in.
THE ORBIT
The shape of the path, where the object sits on it, and the instant those figures were true of. An orbit is a fit to observations and drifts away from the real one either side of its epoch.
- Eccentricity
- ±2.5×10⁻⁵
- Hyperbolic excess velocity
- 57.99
- Inclination
- 175.12
- Longitude of ascending node
- 322.17
- Argument of perihelion
- 128.02
- Mean anomaly
- 818.22
- Element epoch
- 2461090.5000
- Perihelion passage
- 2460977.9953
- Minimum distance from Earth's orbit
- 0.364723
- Orbit class
- HYP
WHEN IT WAS FOUND
Who first saw it, from where, and by what method.
- First observed
- 2025-05-15
ALSO KNOWN AS
] 5 DESIGNATIONS- Comet 2025 N1
- Comet C/2025 N1 (ATLAS)
- Common name C/2025 N1 (ATLAS)
- Interstellar 3I
- Interstellar 3I/ATLAS
LOOK IT UP ELSEWHERE
] 1 SERVICEEach link carries the identifier printed beside it. Nothing on this page is a measurement of our own, so a number that disagrees with one of these is worth reporting — and a service that has never catalogued this object under this name will say so plainly.
- JPL Small-Body Database3I
The orbit these elements were taken from, with its uncertainty, its close approaches and every observation behind the fit.
CITE THIS PAGE
] DR1This page is live and its numbers move when an upstream refreshes, so the citation names the release the rows belong to rather than the day you read them. The release itself is frozen, republished as a bundle, and is what a data-availability statement should point at.
SpaceCatalog. 3I/ATLAS [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/c-2025-n1-atlas
@misc{spacecatalog_c-2025-n1-atlas,
author = {{SpaceCatalog}},
title = {{3I/ATLAS}},
howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
year = {2026},
url = {https://spacecatalog.org/object/c-2025-n1-atlas},
note = {Catalogue entry, data release DR1 (2026-08-21). Values from JPL Small-Body Database.}
}The values above were taken from JPL Small-Body Database — No licence stated; citation requested. Citing this page does not replace citing that catalogue.
That catalogue asks for this acknowledgement: Solar System Dynamics. (Downloaded 2026, October 1). Small-Body Database Query. https://ssd.jpl.nasa.gov
RECENT ACTIVITY
] 6 ITEMS- Spectral Energy Distribution and Polarimetric Properties of Dust in the Interstellar Comet 3I/ATLAS2026-10-04 · arXiv · PAPER · Seungwon Choi, Masateru Ishiguro, Hiroyuki Naito, Yoonsoo P. Bach, Jooyeon Geem, Bumhoo Lim
- Measuring the Age and Initial Composition of Interstellar Objects2026-10-02 · arXiv · PAPER · Aster G. Barry-Taylor
- On the Compositions of Interstellar Objects2026-09-25 · arXiv · PAPER · Matthew J. Hopkins, Michele T. Bannister, Bertram Bitsch, Chris Lintott, John C. Forbes
- Older than the Sun: Astronomers find new clues to the origin of interstellar comet 3I/ATLAS2026-07-06 · ESO · RELEASE
- Webb finds clues to ancient, distant origin of Comet 3I/ATLAS2026-06-22 · ESA/Webb · RELEASE
- NASA’s Mars Spacecraft Capture Images of Comet 3I/ATLAS2025-11-19 · NASA/JPL · RELEASE
arXiv · ESO · ESA/Webb · NASA/JPL · UPDATED DAILY