1I/'Oumuamua

ASTEROIDHyperbolic asteroid

ILLUSTRATION FROM ECCENTRICITY 1.20

[

OVERVIEW

] ASTEROID

1I/'Oumuamua is a hyperbolic asteroid. Its orbit does not close: it passes within 0.256 of the Sun once and never returns. Its absolute magnitude () is 22.08. Other catalogues list it as 2017 U1 and 'Oumuamua (A/2017 U1). It was discovered in 2017.

The first object seen passing through the Solar System from interstellar space, found on its way out in October 2017. It showed no coma, tumbled rather than spun, and its brightness swung by a factor of ten as it turned — which is why it is usually drawn as an elongated shard, though the shape was inferred from the light curve and never resolved.

WHAT IT IS: Hyperbolic asteroid
HOW BRIGHT IN ITSELF (H)

[

OBSERVING

] FROM WHERE YOU ARE

What it takes to see 1I/'Oumuamua 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.

SEE ITS ORBIT

[

CATALOG DATA

] 12 FIELDS

The 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.

WHAT KIND OF THING IT IS

What the object is in itself, rather than how it happens to look from here.

Rotation period: 7.937

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
Hyperbolic excess velocity: 26.41
Inclination: 122.74
Longitude of ascending node: 24.6
Argument of perihelion: 241.81
Mean anomaly: 51.16
Element epoch: 2458080.5000
Perihelion passage: 2458006.0100
Minimum distance from Earth's orbit: 0.0958
Orbit class: HYA

WHEN IT WAS FOUND

Who first saw it, from where, and by what method.

First observed: 2017-10-14

[

ALSO KNOWN AS

] 5 DESIGNATIONS

Asteroid 2017 U1
Asteroid 'Oumuamua (A/2017 U1)
Common name 'Oumuamua
Interstellar 1I
Interstellar 1I/'Oumuamua

[

CITE THIS PAGE

] DR1

This 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.

PLAIN TEXT

SpaceCatalog. 1I/'Oumuamua [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/2017-u1-oumuamua

BIBTEX

@misc{spacecatalog_2017-u1-oumuamua,
  author       = {{SpaceCatalog}},
  title        = {{1I/'Oumuamua}},
  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
  year         = {2026},
  url          = {https://spacecatalog.org/object/2017-u1-oumuamua},
  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 — Public domain (NASA/JPL). Citing this page does not replace citing that catalogue.

[

RELATED OBJECTS

] 4 LINKED

NAME

CLASS

MASS

DISTANCE

MAG

CONSTELLATION