Interstellar object

1I/ʻOumuamua

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.

Confirmed interstellarHyperbolic (e ≈ 1.20) — unbound

Note

The unusual shape and slight non-gravitational acceleration prompted speculation about an artificial origin; that speculation is not supported by the evidence, and the scientific consensus is a natural body (an ejected planetesimal or comet-like fragment).

Physical & orbital character

Origin:Approached from the general direction of the constellation Lyra; no specific parent star has been identified

Activity:No visible coma or tail; a small non-gravitational acceleration was measured

Size:Highly elongated; very roughly 100–400 m on its long axis (uncertain)

Composition:Dry, reddened surface; no gas or dust detected

How it was identified

Trajectory class:Interstellar Hyperbolic Trajectory

Detection methods:Excess Hyperbolic Velocity Incoming-Trajectory Analysis

Detected by survey:Pan-STARRS

Catalogued by:Minor Planet Center NASA Jet Propulsion Laboratory

Knowledge connections

Trajectory classInterstellar Hyperbolic Trajectory
Associated withExcess Hyperbolic Velocity
Associated withIncoming-Trajectory Analysis
Surveyed byPan-STARRS
Catalogued inMinor Planet Center
Catalogued inNASA Jet Propulsion Laboratory

Sources

Facts on this topic will be cited from these primary and reference sources.

Minor Planet CenterIAU Minor Planet Center
Designations and orbits of asteroids, comets, and minor bodies.
NASA JPLJet Propulsion Laboratory / Solar System Dynamics
Orbital data, ephemerides, and small-body parameters for planets, asteroids, and comets.
NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.
NASA ADSNASA Astrophysics Data System
Bibliographic index of peer-reviewed astronomy and astrophysics literature.

Quick facts

Confirmed interstellar

Designation: 1I/ʻOumuamua
Discovered: 2017-10-19
Discovered by: Robert Weryk (Pan-STARRS)
Survey / facility: Pan-STARRS 1, Haleakalā
Eccentricity: 1.2 (hyperbolic)
Perihelion distance: 0.256 AU
Inclination: 122.7°
Excess velocity: ≈ 26 km/s (velocity relative to the Sun far from perihelion)
Perihelion date: 2017-09-09
Trajectory class: Interstellar Hyperbolic Trajectory

In the sky

Interstellar objects pass through the Solar System once and do not return; this encyclopedia computes no live positions or visibility. For what is genuinely observable tonight, use the Live Sky tools.

Quality & authority

38%

Unreviewed

Completeness: Complete
Source coverage: Complete
Citation coverage: None
Relationship coverage: Complete
Review coverage: None
Image coverage: None

Orbits and designations from the IAU Minor Planet Center and the NASA/JPL Small-Body Database. Unknown values are left blank. See source quality.

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1I/ʻOumuamua

Confirmed interstellarHyperbolic (e ≈ 1.20) — unbound

Physical & orbital character

Origin:Approached from the general direction of the constellation Lyra; no specific parent star has been identified

Activity:No visible coma or tail; a small non-gravitational acceleration was measured

Size:Highly elongated; very roughly 100–400 m on its long axis (uncertain)

Composition:Dry, reddened surface; no gas or dust detected

Sources

Facts on this topic will be cited from these primary and reference sources.

Minor Planet CenterIAU Minor Planet Center

Designations and orbits of asteroids, comets, and minor bodies.

NASA JPLJet Propulsion Laboratory / Solar System Dynamics

Orbital data, ephemerides, and small-body parameters for planets, asteroids, and comets.

NASANational Aeronautics and Space Administration

Mission data, planetary science, space telescopes, and public-domain imagery.

Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.

NASA ADSNASA Astrophysics Data System

Bibliographic index of peer-reviewed astronomy and astrophysics literature.

Quick facts

Confirmed interstellar

Designation

1I/ʻOumuamua

Discovered

2017-10-19

Discovered by

Robert Weryk (Pan-STARRS)

Survey / facility

Pan-STARRS 1, Haleakalā

Eccentricity

1.2 (hyperbolic)

Perihelion distance

0.256 AU

Inclination

122.7°

Excess velocity

≈ 26 km/s (velocity relative to the Sun far from perihelion)

Perihelion date

2017-09-09

Trajectory class

Interstellar Hyperbolic Trajectory