# ʻOumuamua

> Source: [ʻOumuamua](https://en.wikipedia.org/wiki/%CA%BBOumuamua)
> Clipped: 2026-07-06

1I/ʻOumuamua

Interstellar object that passed near Earth in 2017

1I/ʻOumuamua

|  |  |
| --- | --- |
| ʻOumuamua on 28 October 2017[[a]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-2) | |
| Discovery[[2]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NASA171026-3)[[3]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Discovery-4) | |
| [Discovered by](https://en.wikipedia.org/wiki/List_of_minor_planet_discoverers "List of minor planet discoverers") | [Robert Weryk](https://en.wikipedia.org/wiki/Robert_Weryk "Robert Weryk") using [Pan-STARRS](https://en.wikipedia.org/wiki/Pan-STARRS "Pan-STARRS") 1 |
| [Discovery site](https://en.wikipedia.org/wiki/List_of_observatory_codes "List of observatory codes") | [Haleakalā Obs.](https://en.wikipedia.org/wiki/Haleakalā_Observatory "Haleakalā Observatory"), Hawaii |
| Discovery date | 19 October 2017 |
| Designations | |
| Pronunciation | [/oʊˌmuːəˈmuːə/](https://en.wikipedia.org/wiki/Help:IPA/English "Help:IPA/English"), Hawaiian: [[ʔowˈmuwəˈmuwə]](https://en.wikipedia.org/wiki/Help:IPA/Hawaiian "Help:IPA/Hawaiian") [ⓘ](https://en.wikipedia.org/wiki/File:Haw-oumuamua.oga "File:Haw-oumuamua.oga") |
| Named after | [Hawaiian term](https://en.wikipedia.org/wiki/Hawaiian_language "Hawaiian language") for *scout*[[4]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-MPEC2017-V17-5) |
| [Alternative designations](https://en.wikipedia.org/wiki/Provisional_designation_in_astronomy "Provisional designation in astronomy") | * 1I * 1I/ʻOumuamua * 1I/2017 U1 (ʻOumuamua) * A/2017 U1[[5]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-A2017U1-6) * C/2017 U1[[3]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Discovery-4) * P10Ee5V[[6]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-spectrum-7) |
| [Minor planet category](https://en.wikipedia.org/wiki/Minor_planet#Populations "Minor planet") | * [Interstellar object](https://en.wikipedia.org/wiki/Interstellar_object "Interstellar object")[[4]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-MPEC2017-V17-5) * [Hyperbolic asteroid](https://en.wikipedia.org/wiki/Hyperbolic_asteroid "Hyperbolic asteroid")[[7]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-jpldata-8)[[8]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ARX-20180920-9)[[9]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-QM-20181010-10) |
| [Orbital characteristics](https://en.wikipedia.org/wiki/Osculating_orbit "Osculating orbit")[[7]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-jpldata-8) | |
| [Epoch](https://en.wikipedia.org/wiki/Epoch_(astronomy) "Epoch (astronomy)") 23 November 2017 ([JD](https://en.wikipedia.org/wiki/Julian_day "Julian day") 2458080.5) | |
| [Observation arc](https://en.wikipedia.org/wiki/Observation_arc "Observation arc") | 80 days |
| [Perihelion](https://en.wikipedia.org/wiki/Perihelion_and_aphelion "Perihelion and aphelion") | 0.255916±0.000007 [AU](https://en.wikipedia.org/wiki/Astronomical_unit "Astronomical unit") |
| [Semi-major axis](https://en.wikipedia.org/wiki/Semi-major_and_semi-minor_axes "Semi-major and semi-minor axes") | −1.2723±0.0001 AU[[b]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-11) |
| [Eccentricity](https://en.wikipedia.org/wiki/Orbital_eccentricity "Orbital eccentricity") | 1.20113±0.00002 |
| Average [orbital speed](https://en.wikipedia.org/wiki/Orbital_speed "Orbital speed") | * 26.33±0.01 [km/s](https://en.wikipedia.org/wiki/Metre_per_second "Metre per second") (interstellar)[[10]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-pseudoMPEC-12) * 5.55 AU/year |
| [Mean anomaly](https://en.wikipedia.org/wiki/Mean_anomaly#Mean_anomaly_at_epoch "Mean anomaly") | 51.158[°](https://en.wikipedia.org/wiki/Degree_(angle) "Degree (angle)") |
| [Mean motion](https://en.wikipedia.org/wiki/Mean_motion "Mean motion") | 0° 41m 12.12s / day |
| [Inclination](https://en.wikipedia.org/wiki/Orbital_inclination "Orbital inclination") | 122.74° |
| [Longitude of ascending node](https://en.wikipedia.org/wiki/Longitude_of_the_ascending_node "Longitude of the ascending node") | 24.597° |
| [Time of perihelion](https://en.wikipedia.org/wiki/Apsis "Apsis") | 9 September 2017 (87.71 km/s)[[10]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-pseudoMPEC-12) |
| [Argument of perihelion](https://en.wikipedia.org/wiki/Argument_of_periapsis "Argument of periapsis") | 241.811° |
| Earth [MOID](https://en.wikipedia.org/wiki/Minimum_orbit_intersection_distance "Minimum orbit intersection distance") | * 0.0958 AU * 37.3 [LD](https://en.wikipedia.org/wiki/Lunar_distance_(astronomy) "Lunar distance (astronomy)") |
| Jupiter [MOID](https://en.wikipedia.org/wiki/Minimum_orbit_intersection_distance "Minimum orbit intersection distance") | 1.454 AU |
| [Physical characteristics](https://en.wikipedia.org/wiki/Standard_asteroid_physical_characteristics "Standard asteroid physical characteristics") | |
| [Dimensions](https://en.wikipedia.org/wiki/Mean_radius_(astronomy) "Mean radius (astronomy)") | * 115 m × 111 m × 19 m[[11]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Maschenko2019-09-13)[[12]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-JewittSeligman2022-14) * 100–1000 m long[[13]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NASA20181114-15)[[14]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-STD-0181020-16)[[15]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-PHYS-20181022-17) * 230 m × 35 m × 35 m[[16]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Jewitt2017-18)[[17]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NOAO2017-19) (est. at [albedo](https://en.wikipedia.org/wiki/Geometric_albedo "Geometric albedo") 0.10)[[16]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Jewitt2017-18)[[17]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NOAO2017-19) |
| [Synodic rotation period](https://en.wikipedia.org/wiki/Synodic_rotation_period "Synodic rotation period") | [Tumbling](https://en.wikipedia.org/wiki/List_of_tumblers_(small_Solar_System_bodies) "List of tumblers (small Solar System bodies)") (non-principal axis rotation)[[18]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Fraser2018a-20) Reported values include: * 8.10±0.02 [h](https://en.wikipedia.org/wiki/Hour "Hour")[[19]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bolin2017-21) * 8.10±0.42 h[[20]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bannister2017-22) * 6.96+1.45 −0.39 h[[21]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Feng2017-23) |
| [Geometric albedo](https://en.wikipedia.org/wiki/Geometric_albedo "Geometric albedo") | * 0.1 (spectral est.)[[16]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Jewitt2017-18) * 0.06–0.08 (spectral est.)[[20]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bannister2017-22) |
| [Spectral type](https://en.wikipedia.org/wiki/Asteroid_spectral_types "Asteroid spectral types") | * [B–V](https://en.wikipedia.org/wiki/Asteroid_color_indices "Asteroid color indices") = 0.7±0.06[[16]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Jewitt2017-18) * [V-R](https://en.wikipedia.org/wiki/Asteroid_color_indices "Asteroid color indices") = 0.45±0.05[[16]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Jewitt2017-18) * [g-r](https://en.wikipedia.org/wiki/Asteroid_color_indices "Asteroid color indices") = 0.47±0.04[[20]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bannister2017-22) * [r-i](https://en.wikipedia.org/wiki/Asteroid_color_indices "Asteroid color indices") = 0.36±0.16[[20]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bannister2017-22) * [r-J](https://en.wikipedia.org/wiki/Asteroid_color_indices "Asteroid color indices") = 1.20±0.11[[20]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bannister2017-22) |
| [Apparent magnitude](https://en.wikipedia.org/wiki/Apparent_magnitude "Apparent magnitude") | 19.7 to >27.5[[10]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-pseudoMPEC-12)[[22]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-HubbleProposal-24)[[c]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-25) |
| [Absolute magnitude *(H)*](https://en.wikipedia.org/wiki/Absolute_magnitude#Solar_System_bodies_(H) "Absolute magnitude") | 22.08±0.45[[7]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-jpldata-8) |
|  | |

**1I/ʻOumuamua** is the first confirmed [interstellar object](https://en.wikipedia.org/wiki/Interstellar_object "Interstellar object") detected passing through the [Solar System](https://en.wikipedia.org/wiki/Solar_System "Solar System").[[23]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-26) [Formally designated](https://en.wikipedia.org/wiki/Naming_of_comets#Current_system "Naming of comets") **1I/2017 U1**, it was discovered by [Canadian](https://en.wikipedia.org/wiki/Canadians "Canadians") [Robert Weryk](https://en.wikipedia.org/wiki/Robert_Weryk "Robert Weryk") using the [Pan-STARRS](https://en.wikipedia.org/wiki/Pan-STARRS "Pan-STARRS") telescope at [Haleakalā Observatory](https://en.wikipedia.org/wiki/Haleakalā_Observatory "Haleakalā Observatory"), [Hawaii](https://en.wikipedia.org/wiki/Hawaii "Hawaii"), on 19 October 2017, approximately 40 days after it passed its [closest point to the Sun](https://en.wikipedia.org/wiki/Apsis#Perihelion_and_aphelion "Apsis") on 9 September. When it was first observed, it was about 33 million km (21 million mi; 0.22 [AU](https://en.wikipedia.org/wiki/Astronomical_unit "Astronomical unit")) from Earth (about 85 times as far away as the Moon) and already heading away from the Sun.

ʻOumuamua is a small object estimated to be between 100 and 1,000 metres (300 and 3,000 ft) long, with its width and thickness both estimated between 35 and 167 metres (115 and 548 ft).[[13]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NASA20181114-15) It has a red color, like objects in the [outer Solar System](https://en.wikipedia.org/wiki/Outer_Solar_System "Outer Solar System"). Despite its close approach to the Sun, it showed no signs of having a [coma](https://en.wikipedia.org/wiki/Coma_(comet) "Coma (comet)"), the usual nebula around comets formed when they pass near the [Sun](https://en.wikipedia.org/wiki/Sun "Sun"). Further, it exhibited [non‑gravitational acceleration](https://en.wikipedia.org/wiki/Gravitational_acceleration "Gravitational acceleration"), potentially due to [outgassing](https://en.wikipedia.org/wiki/Outgassing "Outgassing") or a push from solar [radiation pressure](https://en.wikipedia.org/wiki/Radiation_pressure "Radiation pressure").[[24]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-SLN-20190312-27)[[25]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Nature_27-6-2018-28) It has a rotation rate similar to the Solar System's asteroids, but many valid models permit it to be unusually more elongated than all but a few other natural bodies observed in the solar system. This feature raised speculation about its origin. Its [light curve](https://en.wikipedia.org/wiki/Light_curve "Light curve"), assuming little systematic error, presents its motion as "[tumbling](https://en.wikipedia.org/wiki/Tumbling_(rigid_body) "Tumbling (rigid body)")" rather than "spinning", and moving sufficiently fast relative to the Sun that it is likely of [extrasolar](https://en.wikipedia.org/wiki/Extrasolar_object "Extrasolar object") origin. [Extrapolated](https://en.wikipedia.org/wiki/Extrapolated "Extrapolated") and without further deceleration, its path cannot be captured into a solar orbit, so it will eventually leave the Solar System and continue into [interstellar space](https://en.wikipedia.org/wiki/Interstellar_space "Interstellar space"). Its [planetary system](https://en.wikipedia.org/wiki/Planetary_system "Planetary system") of origin and age are unknown.

ʻOumuamua is remarkable for its extrasolar origin, high [obliqueness](https://en.wikipedia.org/wiki/Axial_tilt "Axial tilt"), and observed acceleration without an apparent coma. By July 2019, most astronomers concluded that it was a natural object, but its precise characterization is contentious given the limited time window for observation. While an unconsolidated object (rubble pile) would require ʻOumuamua to be of a density similar to rocky asteroids,[[26]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-29) a small amount of internal strength similar to icy comets[[27]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-30) would allow it to have a relatively low density. Proposed explanations of its origin include the remnant of a disintegrated [rogue comet](https://en.wikipedia.org/wiki/Exocomet "Exocomet"),[[28]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-UT-20190201-31)[[29]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ARX-20190201-32) or a piece of an [exoplanet](https://en.wikipedia.org/wiki/Exoplanet "Exoplanet") rich in [nitrogen ice](https://en.wikipedia.org/wiki/Nitrogen_ice "Nitrogen ice"), similar to [Pluto](https://en.wikipedia.org/wiki/Pluto "Pluto").[[30]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-JGRP-20210316a-33)[[31]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-JGRP-20210316b-34)[[32]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NYT-20210323-35) On 22 March 2023, astronomers proposed the observed acceleration was "due to the release of entrapped molecular hydrogen that formed through energetic processing of an H2O-rich icy body",[[33]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NAT-20230322-36) consistent with ʻOumuamua being an interstellar comet, "originating as a [planetesimal](https://en.wikipedia.org/wiki/Planetesimal "Planetesimal") relic broadly similar to solar system comets".[[34]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NYT-20230322-37)

## Name

[![](https://upload.wikimedia.org/wikipedia/commons/thumb/2/20/Oumuamua_orbit_at_perihelion.png/250px-Oumuamua_orbit_at_perihelion.png)](https://en.wikipedia.org/wiki/File:Oumuamua_orbit_at_perihelion.png)

[Hyperbolic trajectory](https://en.wikipedia.org/wiki/Hyperbolic_trajectory "Hyperbolic trajectory") of ʻOumuamua, during 2017, through the [inner Solar System](https://en.wikipedia.org/wiki/Inner_Solar_System "Inner Solar System") with the Sun at the [focus](https://en.wikipedia.org/wiki/Focus_(geometry) "Focus (geometry)")[[35]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-38)

As the first known object of its type, ʻOumuamua presented a unique case for the [International Astronomical Union](https://en.wikipedia.org/wiki/International_Astronomical_Union "International Astronomical Union"), which assigns designations for astronomical objects. Originally classified as comet C/2017 U1, it was later reclassified as asteroid A/2017 U1 due to the absence of a coma. Once it was unambiguously identified as coming from outside the Solar System, a [new designation](https://en.wikipedia.org/wiki/Naming_of_comets#Current_system "Naming of comets") was created: I, for Interstellar object. As the first object so identified, ʻOumuamua was designated 1I, with rules for the eligibility of objects for I-numbers and the names to be assigned to these interstellar objects yet to be codified. The object may be called 1I; 1I/2017 U1; 1I/ʻOumuamua; or 1I/2017 U1 (ʻOumuamua).[[4]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-MPEC2017-V17-5)

The name comes from [Hawaiian](https://en.wikipedia.org/wiki/Hawaiian_language "Hawaiian language")  *[ʻoumuamua](https://en.wiktionary.org/wiki/ʻoumuamua#Hawaiian "wikt:ʻoumuamua")* 'scout'[[36]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Pukui-Elbert-39) (from  *[ʻou](https://en.wiktionary.org/wiki/ʻou#Hawaiian "wikt:ʻou")* 'reach out for' and  *[mua](https://en.wiktionary.org/wiki/mua#Hawaiian "wikt:mua"), [reduplicated](https://en.wikipedia.org/wiki/Reduplication "Reduplication") for emphasis* 'first, in advance of'[[4]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-MPEC2017-V17-5)), and reflects the way the object is like a scout or messenger sent from the distant past to reach out to humanity. It roughly translates to 'first distant messenger'.[[4]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-MPEC2017-V17-5)[[37]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Outerplaces-40) The first character (not a [diacritic](https://en.wikipedia.org/wiki/Diacritic "Diacritic")) is a Hawaiian [ʻokina](https://en.wikipedia.org/wiki/ʻOkina "ʻOkina"), not an [apostrophe](https://en.wikipedia.org/wiki/Apostrophe "Apostrophe"), and is pronounced as a [glottal stop](https://en.wikipedia.org/wiki/Glottal_stop "Glottal stop"); the Pan-STARRS team chose the name[[38]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-41) in consultation with [Kaʻiu Kimura](https://en.wikipedia.org/wiki/Kaʻiu_Kimura "Kaʻiu Kimura") and [Larry Kimura](https://en.wikipedia.org/wiki/Larry_Kimura "Larry Kimura") of the [University of Hawaiʻi at Hilo](https://en.wikipedia.org/wiki/University_of_Hawaiʻi_at_Hilo "University of Hawaiʻi at Hilo").[[39]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-42)

Before the official name was decided, *Rama* was suggested, the name given to an alien spacecraft discovered under similar circumstances in the 1973 science fiction novel *[Rendezvous with Rama](https://en.wikipedia.org/wiki/Rendezvous_with_Rama "Rendezvous with Rama")* by [Arthur C. Clarke](https://en.wikipedia.org/wiki/Arthur_C._Clarke "Arthur C. Clarke").[[40]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-43)

## Observations

Observations and conclusions concerning ʻOumuamua's trajectory were primarily obtained with data from the [Pan-STARRS1 Telescope](https://en.wikipedia.org/wiki/Pan-STARRS#Instruments "Pan-STARRS"), part of the [Spaceguard Survey](https://en.wikipedia.org/wiki/Spaceguard "Spaceguard"),[[41]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-44) and the [Canada–France–Hawaii Telescope](https://en.wikipedia.org/wiki/Canada–France–Hawaii_Telescope "Canada–France–Hawaii Telescope") (CFHT), and its composition and shape from the [Very Large Telescope](https://en.wikipedia.org/wiki/Very_Large_Telescope "Very Large Telescope") and the [Gemini South](https://en.wikipedia.org/wiki/Gemini_South "Gemini South") telescope in Chile,[[42]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Gemini-45) and the [Keck II](https://en.wikipedia.org/wiki/W._M._Keck_Observatory "W. M. Keck Observatory") telescope in Hawaii. These were collected by [Karen J. Meech](https://en.wikipedia.org/wiki/Karen_J._Meech "Karen J. Meech"), Robert Weryk, and their colleagues and published in *[Nature](https://en.wikipedia.org/wiki/Nature_(journal) "Nature (journal)")* on 20 November 2017.[[43]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NAT-20171120-46)[[44]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Rincon2017-47) After the announcement, the space-based telescopes [Hubble](https://en.wikipedia.org/wiki/Hubble_Space_Telescope "Hubble Space Telescope") and [Spitzer](https://en.wikipedia.org/wiki/Spitzer_Space_Telescope "Spitzer Space Telescope") joined in the observations.[[45]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-jpl-news-48)

[![](https://upload.wikimedia.org/wikipedia/commons/thumb/2/26/Oumuamua_magnitude_2015-2019.png/250px-Oumuamua_magnitude_2015-2019.png)](https://en.wikipedia.org/wiki/File:Oumuamua_magnitude_2015-2019.png)

ʻOumuamua had faded to 34th magnitude by 2020.

ʻOumuamua is small and not very luminous. It was not seen in [STEREO HI-1A](https://en.wikipedia.org/wiki/STEREO "STEREO") observations near its perihelion on 9 September 2017, limiting its brightness to approximately 13.5 [mag](https://en.wikipedia.org/wiki/Apparent_magnitude "Apparent magnitude").[[20]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bannister2017-22) By the end of October, it had already faded to about [apparent magnitude](https://en.wikipedia.org/wiki/Apparent_magnitude "Apparent magnitude") 23,[[46]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-MPC-object-49) and in mid-December 2017, it was too faint and fast-moving to be studied by even the largest ground-based telescopes.[[42]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Gemini-45)

ʻOumuamua was compared to the [fictional alien spacecraft *Rama*](https://en.wikipedia.org/wiki/Rendezvous_with_Rama "Rendezvous with Rama") due to its interstellar origin. Adding to the coincidence, both the real and the fictional objects are unusually elongated.[[47]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Koren-20171211-50) ʻOumuamua has a reddish hue and unsteady brightness, which are typical of asteroids.[[48]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-wenz2017-51)[[49]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NYT-20171122-52)[[50]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-53)

The [SETI Institute](https://en.wikipedia.org/wiki/SETI_Institute "SETI Institute")'s [radio telescope](https://en.wikipedia.org/wiki/Radio_telescope "Radio telescope"), the [Allen Telescope Array](https://en.wikipedia.org/wiki/Allen_Telescope_Array "Allen Telescope Array"), examined ʻOumuamua, but detected no unusual [radio emissions](https://en.wikipedia.org/wiki/Radio_emission "Radio emission").[[51]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-SETI-54) More detailed observations, using the [Breakthrough Listen](https://en.wikipedia.org/wiki/Breakthrough_Listen "Breakthrough Listen") hardware and the [Green Bank Telescope](https://en.wikipedia.org/wiki/Green_Bank_Telescope "Green Bank Telescope"), were performed;[[47]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Koren-20171211-50)[[51]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-SETI-54)[[52]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-55) the data were searched for narrowband signals and none were found. Given the close proximity to this interstellar object, limits were placed to putative transmitters with the extremely low [effective isotropically radiated power](https://en.wikipedia.org/wiki/Effective_radiated_power "Effective radiated power") of 0.08 watts.[[53]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-No_narrowband_signals_found.-56)

### Trajectory

[![](https://upload.wikimedia.org/wikipedia/commons/thumb/4/41/Oumuamua-skypath.png/250px-Oumuamua-skypath.png)](https://en.wikipedia.org/wiki/File:Oumuamua-skypath.png)

Seen from Earth, the [apparent trajectory](https://en.wikipedia.org/wiki/Apparent_place "Apparent place") makes annual retrograde loops in the sky, with its origin in [Lyra](https://en.wikipedia.org/wiki/Lyra_(constellation) "Lyra (constellation)"), temporarily moving south of the ecliptic between 2 September and 22 October 2017, and moving northward again towards its destination in [Pegasus](https://en.wikipedia.org/wiki/Pegasus_(constellation) "Pegasus (constellation)").

[![](https://upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Oumuamua-solar_system-ecliptic-normals.png/250px-Oumuamua-solar_system-ecliptic-normals.png)](https://en.wikipedia.org/wiki/File:Oumuamua-solar_system-ecliptic-normals.png)

ʻOumuamua's hyperbolic trajectory over the Solar System

ʻOumuamua appears to have come from roughly the direction of [Vega](https://en.wikipedia.org/wiki/Vega "Vega") in the constellation [Lyra](https://en.wikipedia.org/wiki/Lyra_(constellation) "Lyra (constellation)").[[48]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-wenz2017-51)[[49]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NYT-20171122-52)[[54]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-skyandtelescope-57)[[55]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-58) Its inbound direction of motion is 6° from the [solar apex](https://en.wikipedia.org/wiki/Solar_apex "Solar apex") (the direction of the Sun's movement relative to local stars), the most likely direction from which objects from outside the Solar System would come.[[54]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-skyandtelescope-57)[[56]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Hein2017-59) On 26 October, two [precovery](https://en.wikipedia.org/wiki/Precovery "Precovery") observations from the [Catalina Sky Survey](https://en.wikipedia.org/wiki/Catalina_Sky_Survey "Catalina Sky Survey") were found dated 14 and 17 October.[[57]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-precoveryobs-60)[[46]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-MPC-object-49) A two-week [observation arc](https://en.wikipedia.org/wiki/Observation_arc "Observation arc") had verified a strongly [hyperbolic trajectory](https://en.wikipedia.org/wiki/Hyperbolic_trajectory "Hyperbolic trajectory").[[7]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-jpldata-8)[[43]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NAT-20171120-46) It has a [hyperbolic excess velocity](https://en.wikipedia.org/wiki/Hyperbolic_excess_velocity "Hyperbolic excess velocity") (velocity at infinity, 


v

∞

{\displaystyle v_{\infty }\!}
![{\displaystyle v_{\infty }\!}](https://wikimedia.org/api/rest_v1/media/math/render/svg/4439fe0f5c56e071edb64af0bd2c916211475fe4)) of 26.33 [km/s](https://en.wikipedia.org/wiki/Metre_per_second "Metre per second") (94,800 [km/h](https://en.wikipedia.org/wiki/Kilometres_per_hour "Kilometres per hour"); 58,900 [mph](https://en.wikipedia.org/wiki/Miles_per_hour "Miles per hour")), its speed relative to the Sun when in interstellar space.[[d]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-61)

ʻOumuamua speed relative to the Sun

| Distance | Date | Velocity (km/s) |
| --- | --- | --- |
| 2300 AU | 1606 | 26.41[[58]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-62) |
| 1000 AU | 1839 | 26.42 |
| 100 AU | 2000 | 26.73 |
| 10 AU | 2016 | 29.56 |
| 1 AU | 9 August 2017 | 49.70[[59]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-63) |
| [Perihelion](https://en.wikipedia.org/wiki/Perihelion_and_aphelion "Perihelion and aphelion") | 9 September 2017 | 87.71[[10]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-pseudoMPEC-12) |
| 1 AU | 10 October 2017 | 49.70[[e]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-64) |
| 10 AU | 2019 | 29.58 |
| 100 AU | 2034 | 26.73[[60]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-65) |
| 1000 AU | 2195 | 26.44 |
| 2300 AU | 2429 | 26.40[[61]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-66) |

By mid-November, astronomers were certain that it was an interstellar object.[[62]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-67) Based on observations spanning 80 days, ʻOumuamua's [orbital eccentricity](https://en.wikipedia.org/wiki/Orbital_eccentricity "Orbital eccentricity") is 1.20, the highest ever observed[[63]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-JPL-ecc-68)[[10]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-pseudoMPEC-12) until [2I/Borisov](https://en.wikipedia.org/wiki/2I/Borisov "2I/Borisov") was discovered in August 2019. An [eccentricity exceeding 1.0](https://en.wikipedia.org/wiki/Hyperbola "Hyperbola") means an object exceeds the Sun's [escape velocity](https://en.wikipedia.org/wiki/Escape_velocity "Escape velocity"), is not bound to the Solar System, and may escape to interstellar space. While an eccentricity slightly above 1.0 can be obtained by encounters with planets, as happened with the previous record holder, [C/1980 E1](https://en.wikipedia.org/wiki/C/1980_E1_(Bowell) "C/1980 E1 (Bowell)"),[[63]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-JPL-ecc-68)[[64]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-orientation-69)[[f]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-70) ʻOumuamua's eccentricity is so high that it could not have been obtained through an encounter with any of the planets in the Solar System. Even undiscovered planets in the Solar System cannot account for ʻOumuamua's trajectory or boost its speed to the observed value. For these reasons, it can only be of interstellar origin.[[65]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Wright-71)[[66]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-hyperbolics-72)

[![](https://upload.wikimedia.org/wikipedia/commons/thumb/1/1d/Comet_20171025-16_gif.gif/250px-Comet_20171025-16_gif.gif)](https://en.wikipedia.org/wiki/File:Comet_20171025-16_gif.gif)

Animation of ʻOumuamua passing through the Solar System

Inbound velocity at 200 AU from the Sun  
compared to Oort cloud objects

| Object | Velocity (km/s) | # of observations  and [obs arc](https://en.wikipedia.org/wiki/Observation_arc "Observation arc")[[g]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-73) |
| --- | --- | --- |
| [90377 Sedna](https://en.wikipedia.org/wiki/90377_Sedna "90377 Sedna") | 2.66[[67]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-74) | 577 in 12512 days |
| [C/2010 X1 (Elenin)](https://en.wikipedia.org/wiki/C/2010_X1_(Elenin) "C/2010 X1 (Elenin)") | 2.96 | 2222 in 235 days |
| [C/1980 E1 (Bowell)](https://en.wikipedia.org/wiki/C/1980_E1_(Bowell) "C/1980 E1 (Bowell)") | 2.98[[68]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-75) | 187 in 2514 days |
| C/1997 P2 (Spacewatch) | 2.99 | 94 in 49 days |
| [C/2012 S1 (ISON)](https://en.wikipedia.org/wiki/C/2012_S1_(ISON) "C/2012 S1 (ISON)") | 2.99[[69]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-76) | 6514 in 784 days |
| **1I/2017 U1 (ʻOumuamua)** | 26.55[[70]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-77) | 207 in 80 days |
| [2I/Borisov](https://en.wikipedia.org/wiki/2I/Borisov "2I/Borisov") | 32.43[[71]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-78) | 3249 in 657 days |

ʻOumuamua entered the Solar System from north of the plane of the [ecliptic](https://en.wikipedia.org/wiki/Ecliptic "Ecliptic"). The pull of the Sun's gravity caused it to speed up until it reached its maximum speed of 87.71 km/s (315,800 km/h; 196,200 mph) as it passed south of the ecliptic on 6 September, where the Sun's gravity bent its orbit in a sharp turn northward at its closest approach (perihelion) on 9 September at a distance of 0.255 [AU](https://en.wikipedia.org/wiki/Astronomical_unit "Astronomical unit") (38,100,000 [km](https://en.wikipedia.org/wiki/Kilometre "Kilometre"); 23,700,000 [mi](https://en.wikipedia.org/wiki/Mile "Mile")) from the Sun, i.e., about 17% closer than [Mercury](https://en.wikipedia.org/wiki/Mercury_(planet) "Mercury (planet)")'s closest approach to the Sun.[[72]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NASA-FAQ-79)[[10]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-pseudoMPEC-12)[[h]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-81) It is now heading away from the Sun toward [Pegasus](https://en.wikipedia.org/wiki/Pegasus_(constellation) "Pegasus (constellation)"), toward a vanishing point 66° from the direction of its approach.[[i]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-82)

On the outward leg of its journey through the Solar System, ʻOumuamua passed beyond the orbit of Earth on 14 October with a closest approach distance of approximately 0.16175 AU (24,197,000 km; 15,036,000 mi) from Earth.[[7]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-jpldata-8) On 16 October it moved back north of the ecliptic plane and passed beyond the orbit of Mars on 1 November.[[72]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NASA-FAQ-79)[[54]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-skyandtelescope-57)[[7]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-jpldata-8) It passed beyond Jupiter's orbit in May 2018, beyond Saturn's orbit in January 2019, and beyond Neptune's in 2022.[[72]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NASA-FAQ-79) As it leaves the Solar System it will be approximately [right ascension](https://en.wikipedia.org/wiki/Right_ascension "Right ascension") 23'51" and [declination](https://en.wikipedia.org/wiki/Declination "Declination") +24°42', in [Pegasus](https://en.wikipedia.org/wiki/Pegasus_(constellation) "Pegasus (constellation)").[[10]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-pseudoMPEC-12) It will continue to slow down, approaching a speed of 26.33 kilometres per second (94,800 km/h; 58,900 mph) relative to the Sun, the same speed it had before its approach to the Solar System.[[10]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-pseudoMPEC-12)

#### Non-gravitational acceleration

On 27 June 2018, astronomers reported a non-gravitational acceleration to ʻOumuamua's trajectory, potentially consistent with a push from solar radiation pressure.[[74]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-UT-230181031-83)[[75]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ARX-20181101-84) The resulting change in velocity during the period when it was near its closest approach to the Sun summed to about 17 meters per second. Initial speculation as to the cause of this acceleration pointed to the comet-like outgassing,[[25]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Nature_27-6-2018-28) whereby volatile substances inside the object evaporate as the Sun heats its surface. Although no such tail of gasses was observed following the object,[[76]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ARX-20181108072-85) researchers estimated that enough outgassing may have increased the object's speed without the gases being detectable.[[77]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NASA-20180627nasa-86) A critical reassessment of the outgassing hypothesis argued that, instead of the observed stability of ʻOumuamua's spin, outgassing would have caused its spin to rapidly change due to its elongated shape, resulting in the object tearing apart.[[8]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ARX-20180920-9)

#### Indications of origin

Accounting for Vega's [proper motion](https://en.wikipedia.org/wiki/Proper_motion "Proper motion"), it would have taken ʻOumuamua 600,000 years to reach the Solar System from Vega, although it was not in the same part of the sky at that time.[[43]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NAT-20171120-46)[[54]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-skyandtelescope-57) Astronomers calculate that 100 years ago the object was 83.9 ± 0.090 billion km; 52.1 ± 0.056 billion mi (561 ± 0.6 AU) from the Sun and traveling at 26.33 km/s with respect to the Sun.[[10]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-pseudoMPEC-12) This interstellar speed is very close to the mean motion of material in the Milky Way in the neighborhood of the Sun, also known as the [local standard of rest](https://en.wikipedia.org/wiki/Local_standard_of_rest "Local standard of rest") (LSR), and especially close to the mean motion of a relatively close group of [red dwarf](https://en.wikipedia.org/wiki/Red_dwarf "Red dwarf") stars. This velocity profile also indicates an extrasolar origin, but appears to rule out the [closest dozen stars](https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs "List of nearest stars and brown dwarfs").[[78]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Mamajek2017-87) In fact, the closeness of ʻOumuamua's velocity to the local standard of rest might mean that it has circulated the Milky Way several times and thus may have originated from an entirely different part of the galaxy.[[43]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NAT-20171120-46)

It is unknown how long the object has been traveling among the stars.[[72]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NASA-FAQ-79) The Solar System is likely the first [planetary system](https://en.wikipedia.org/wiki/Planetary_system "Planetary system") ʻOumuamua has closely encountered since being ejected from its birth star system, potentially several billion years ago.[[79]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Ye2017-88)[[43]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NAT-20171120-46) It has been speculated that the object may have been ejected from a stellar system in one of the local [kinematic associations](https://en.wikipedia.org/wiki/Stellar_kinematic_group "Stellar kinematic group") of [young stars](https://en.wikipedia.org/wiki/Young_star "Young star") (specifically, [Carina](https://en.wikipedia.org/wiki/Carina_OB1 "Carina OB1") or Columba) within a range of about 100 [parsecs](https://en.wikipedia.org/wiki/Parsec "Parsec"),[[80]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-89) 45 million years ago.[[81]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Gaidos2017-90) The Carina and Columba associations are now very far in the sky from the [Lyra](https://en.wikipedia.org/wiki/Lyra "Lyra") constellation, the direction from which ʻOumuamua came when it entered the Solar System. Others have speculated that it was ejected from a white dwarf system and that its volatiles were lost when its parent star became a red giant.[[82]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-white_dwarf-91) About 1.3 million years ago the object may have passed within a distance of 0.16 [parsecs](https://en.wikipedia.org/wiki/Parsec "Parsec") (0.52 [light-years](https://en.wikipedia.org/wiki/Light-year "Light-year")) to the nearby star [TYC 4742-1027-1](https://en.wikipedia.org/wiki/TYC_4742-1027-1?action=edit&redlink=1 "TYC 4742-1027-1"), but its velocity is too high to have originated from that star system, and it probably just passed through the system's [Oort cloud](https://en.wikipedia.org/wiki/Oort_cloud "Oort cloud") at a relative speed of about 15 km/s (34,000 mph; 54,000 km/h).[[83]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-PortegiesZwartetal2017-92)[[j]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-93) An August 2018 study using [Gaia Data Release 2](https://en.wikipedia.org/wiki/Gaia_Data_Release_2 "Gaia Data Release 2") updated the possible past close encounters and identified four stars—[HIP 3757](https://en.wikipedia.org/wiki/HIP_3757?action=edit&redlink=1 "HIP 3757"), [HD 292249](https://en.wikipedia.org/wiki/HD_292249?action=edit&redlink=1 "HD 292249"), [Gaia DR2](https://en.wikipedia.org/wiki/Gaia_DR2 "Gaia DR2") 2502921019565490176, and [Gaia DR2](https://en.wikipedia.org/wiki/Gaia_DR2 "Gaia DR2") 3666992950762141312—which ʻOumuamua passed relatively close to at moderately low velocities in the past few million years.[[84]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bailer-Jones2018-94) This study also identifies future close encounters of ʻOumuamua on its outgoing trajectory from the Sun.[[85]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-95)

In September 2018, astronomers described several possible home [star systems](https://en.wikipedia.org/wiki/Star_system "Star system") from which ʻOumuamua may have originated.[[86]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ARX-20180924-96)[[87]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-97) In April 2020, astronomers presented a new possible scenario for the object's origin.[[88]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-EA-20200413-98)[[89]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NA-20200413-99) According to one hypothesis, ʻOumuamua could be a fragment from a [tidally disrupted planet](https://en.wikipedia.org/wiki/Disrupted_planet "Disrupted planet").[[90]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-100)[[k]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-101) If true, this would make ʻOumuamua a rare object, of a type much less abundant than most extrasolar "dusty-snowball" comets or asteroids. But this scenario leads to cigar-shaped objects, whereas ʻOumuamua's lightcurve favors a disc-like shape.[[11]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Maschenko2019-09-13) In May 2020, it was proposed that the object was the first observed member of a class of small [H2-ice](https://en.wikipedia.org/wiki/Solid_hydrogen "Solid hydrogen")-rich bodies that form at temperatures near 3 K in the cores of [giant molecular clouds](https://en.wikipedia.org/wiki/Giant_molecular_clouds "Giant molecular clouds"). The non-gravitational acceleration and high aspect ratio shape of ʻOumuamua might be explainable on this basis.[[91]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Seligman2020-05-102) However, it was later calculated that hydrogen icebergs cannot survive their journey through interstellar space.[[92]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Hoang2020-06-103)

### Classification

Initially, ʻOumuamua was announced as comet C/2017 U1 (PANSTARRS) based on a strongly hyperbolic trajectory.[[3]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Discovery-4) In an attempt to confirm any cometary activity, very deep [stacked images](https://en.wikipedia.org/wiki/Shift-and-add "Shift-and-add") were taken at the [Very Large Telescope](https://en.wikipedia.org/wiki/Very_Large_Telescope "Very Large Telescope") later the same day, but the object showed no presence of a [coma](https://en.wikipedia.org/wiki/Coma_(cometary) "Coma (cometary)").[[l]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-104) Accordingly, the object was renamed A/2017 U1, becoming the first comet ever to be [re-designated as an asteroid](https://en.wikipedia.org/wiki/Naming_of_comets#Current_system "Naming of comets").[[5]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-A2017U1-6) Once it was identified as an interstellar object, it was designated 1I/2017 U1, the first member of a new class of objects.[[4]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-MPEC2017-V17-5) The lack of a coma limits the amount of surface ice to a few square meters, and any [volatiles](https://en.wikipedia.org/wiki/Volatile_(astrogeology) "Volatile (astrogeology)") (if they exist) must lie below a crust at least 0.5 m (1.6 ft) thick.[[16]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Jewitt2017-18) It also indicates that the object must have formed within the [frost line](https://en.wikipedia.org/wiki/Frost_line_(astrophysics) "Frost line (astrophysics)") of its parent stellar system or have been in the inner region of that stellar system long enough for all near-surface ice to [sublimate](https://en.wikipedia.org/wiki/Sublimation_(phase_transition) "Sublimation (phase transition)"), as may be the case with [damocloids](https://en.wikipedia.org/wiki/Damocloid "Damocloid").[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")*] It is difficult to say which scenario is more likely due to the chaotic nature of small body dynamics,[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")*] although if it formed in a similar manner to Solar System objects, its spectrum indicates that the latter scenario is true. Any [meteoric activity](https://en.wikipedia.org/wiki/Meteor "Meteor") from ʻOumuamua would have been expected to occur on 18 October 2017 coming from the constellation [Sextans](https://en.wikipedia.org/wiki/Sextans "Sextans"), but no activity was detected by the [Canadian Meteor Orbit Radar](https://en.wikipedia.org/wiki/Canadian_Meteor_Orbit_Radar?action=edit&redlink=1 "Canadian Meteor Orbit Radar").[[79]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Ye2017-88)

On 27 June 2018, astronomers reported that ʻOumuamua was thought to be a mildly active [comet](https://en.wikipedia.org/wiki/Comet "Comet"), and not an [asteroid](https://en.wikipedia.org/wiki/Asteroid "Asteroid"), as previously thought. This was determined by measuring a non-gravitational boost to ʻOumuamua's acceleration, consistent with comet outgassing.[[25]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Nature_27-6-2018-28)[[93]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NAT-20180627-105)[[77]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NASA-20180627nasa-86)[[94]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-eso1820June2018Oumuamua-106) However, studies submitted in October 2018 suggest that the object is neither an asteroid nor a comet,[[8]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ARX-20180920-9)[[9]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-QM-20181010-10) although the object could be a remnant of a disintegrated [interstellar comet](https://en.wikipedia.org/wiki/Interstellar_comet "Interstellar comet") (or [exocomet](https://en.wikipedia.org/wiki/Exocomet "Exocomet")), as suggested by astronomer [Zdenek Sekanina](https://en.wikipedia.org/wiki/Zdenek_Sekanina "Zdenek Sekanina").[[28]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-UT-20190201-31)[[29]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ARX-20190201-32) But by 2024, astronomers had identified 14 asteroids with the same unusual behavior.[[95]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-darkComet-107) This makes 'Oumuamua the first member of another new class of objects called [dark comets](https://en.wikipedia.org/wiki/Dark_comet "Dark comet").[[95]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-darkComet-107)

### Appearance, shape and composition

Spectra from the Hale Telescope on 25 October showed red color resembling comet nuclei or [Trojans](https://en.wikipedia.org/wiki/Trojan_(astronomy) "Trojan (astronomy)").[[79]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Ye2017-88) Higher signal to noise spectra recorded by the 4.2 m (14 ft) [William Herschel Telescope](https://en.wikipedia.org/wiki/William_Herschel_Telescope "William Herschel Telescope") later that day showed that the object was featureless, and [colored red](https://en.wikipedia.org/wiki/Trans-Neptunian_object#Colors "Trans-Neptunian object") like [Kuiper belt](https://en.wikipedia.org/wiki/Kuiper_belt "Kuiper belt") objects.[[96]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-WHT-108) Spectra obtained with the 8.2 m (27 ft) [Very Large Telescope](https://en.wikipedia.org/wiki/Very_Large_Telescope "Very Large Telescope") the following night showed that behavior continued into near-infrared wavelengths.[[97]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Fitzsimmons2017a-109) Its spectrum is similar to that of [D-type asteroids](https://en.wikipedia.org/wiki/D-type_asteroid "D-type asteroid").[[16]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Jewitt2017-18)

[![](https://upload.wikimedia.org/wikipedia/commons/thumb/3/3d/Eso1737f.svg/960px-Eso1737f.svg.png)](https://en.wikipedia.org/wiki/File:Eso1737f.svg)

[Light curve](https://en.wikipedia.org/wiki/Light_curve "Light curve") from 25 to 27 October 2017 with dotted line from a model with 10:1 elongation

ʻOumuamua is not rotating around a [principal axis](https://en.wikipedia.org/wiki/Principal_axis_(mechanics) "Principal axis (mechanics)"), and its motion may be a form of [tumbling](https://en.wikipedia.org/wiki/Tumbling_(rigid_body) "Tumbling (rigid body)").[[18]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Fraser2018a-20)[[98]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-110) This accounts for the various rotation periods reported, such as 8.10 hours (±0.42 hours[[20]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bannister2017-22) or ±0.02 hours[[19]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bolin2017-21)) by Bannister et al. and Bolin et al. with a lightcurve amplitude of 1.5–2.1 magnitudes,[[19]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bolin2017-21) whereas Meech et al. reported a rotation period of 7.3 hours and a lightcurve amplitude of 2.5 magnitudes.[[99]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ESO2017-111)[[m]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-112) Most likely, ʻOumuamua was set tumbling by a collision in its system of origin, and remains tumbling since the time scale for dissipation of this motion is very long, at least a billion years.[[18]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Fraser2018a-20)[[100]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-113)

[![](https://upload.wikimedia.org/wikipedia/commons/6/6c/Oumuamua_light_curve_simulation.gif)](https://en.wikipedia.org/wiki/File:ʻOumuamua_light_curve_simulation.gif)

Simulation of ʻOumuamua spinning and tumbling through space, and the resultant light curve. In reality, observations of ʻOumuamua detect the object as a single pixel – its shape here has been inferred from the light curve.

The large variations on the light curves indicate that ʻOumuamua may be anything from a highly elongated [cigar](https://en.wikipedia.org/wiki/Cigar "Cigar")-like object, comparable to or greater than the most elongated Solar System objects,[[20]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bannister2017-22)[[19]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bolin2017-21) to an extremely flat object, a pancake or oblate [spheroid](https://en.wikipedia.org/wiki/Spheroid "Spheroid").[[101]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-114) However, the size and shape have not been directly observed as ʻOumuamua appears as nothing more than a point source of light even in the most powerful telescopes. Neither its [albedo](https://en.wikipedia.org/wiki/Geometric_albedo "Geometric albedo") nor its triaxial ellipsoid shape is known. If cigar-shaped, the longest-to-shortest axis ratio could be 5:1 or greater.[[18]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Fraser2018a-20) Assuming an albedo of 10% (slightly higher than typical for D-type asteroids[[102]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-115)) and a 6:1 ratio, ʻOumuamua has dimensions of approximately 100 m–1,000 m × 35 m–167 m × 35 m–167 m (328 ft–3,281 ft × 115 ft–548 ft × 115 ft–548 ft)[[13]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NASA20181114-15)[[14]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-STD-0181020-16)[[15]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-PHYS-20181022-17)[[16]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Jewitt2017-18)[[17]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NOAO2017-19) with an average diameter of about 110 m (360 ft).[[16]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Jewitt2017-18)[[17]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NOAO2017-19) According to astronomer [David C. Jewitt](https://en.wikipedia.org/wiki/David_C._Jewitt "David C. Jewitt"), the object is physically unremarkable except for its highly elongated shape.[[17]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NOAO2017-19) Bannister et al. have suggested that it could also be a [contact binary](https://en.wikipedia.org/wiki/Contact_binary_(small_Solar_System_body) "Contact binary (small Solar System body)"),[[20]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Bannister2017-22) although this may not be compatible with its rapid rotation.[[44]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Rincon2017-47) One speculation regarding its shape is that it is a result of a violent event (such as a collision or stellar explosion) that caused its ejection from its system of origin.[[44]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Rincon2017-47) JPL News reported that ʻOumuamua "is up to one-quarter mile (400 meters) long and highly-elongated — perhaps 10 times as long as it is wide".[[45]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-jpl-news-48)[[103]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Guarddian2017-12-11-116)

[![](https://upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Artist%27s_impression_of_%CA%BBOumuamua.jpg/250px-Artist%27s_impression_of_%CA%BBOumuamua.jpg)](https://en.wikipedia.org/wiki/File:Artist's_impression_of_ʻOumuamua.jpg)

Artist's impression of a cigar-shaped ʻOumuamua

A 2019 paper finds the best models as either a cigar-shape, 1:8 aspect ratio, or disc-shape, 1:6 aspect ratio, with the disc more likely since its rotation does not require a specific orientation to see the range of brightnesses observed.[[104]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Mashchenko2019-117) [Monte Carlo simulations](https://en.wikipedia.org/wiki/Monte_Carlo_method "Monte Carlo method") based on the available orbit determination suggest that the equatorial [obliquity](https://en.wikipedia.org/wiki/Axial_tilt "Axial tilt") of ʻOumuamua could be about 93 degrees, if it has a very prolate or cigar-like shape, or close to 16 degrees, if it is very oblate or disk-like.[[105]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-rotationpole-118) A 2021 paper proposed that, if ʻOumuamua is made of nitrogen ice, the extreme shape could be a result of recent evaporation, and that when the object entered the Solar System it likely had an unremarkable 2:1 aspect ratio. The authors calculated that in this scenario, a month after perihelion, that ʻOumuamua had lost 92% of the mass it had upon entering the Solar System.[[30]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-JGRP-20210316a-33)

[![](https://upload.wikimedia.org/wikipedia/commons/thumb/9/92/First_Known_Interstellar_Visitor_is_an_%E2%80%9COddball%E2%80%9D_%28gemini1710b%29.tiff/lossy-page1-250px-First_Known_Interstellar_Visitor_is_an_%E2%80%9COddball%E2%80%9D_%28gemini1710b%29.tiff.jpg)](https://en.wikipedia.org/wiki/File:First_Known_Interstellar_Visitor_is_an_“Oddball”_(gemini1710b).tiff)

Color composite image taken on 27 October 2017 using the [Gemini South telescope](https://en.wikipedia.org/wiki/Gemini_South_telescope "Gemini South telescope")[[42]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Gemini-45)

[Light curve](https://en.wikipedia.org/wiki/Light_curve "Light curve") observations suggest however that the object may be composed of dense metal-rich rock that has been reddened by millions of years of exposure to [cosmic rays](https://en.wikipedia.org/wiki/Cosmic_ray "Cosmic ray").[[44]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Rincon2017-47)[[106]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-119)[[107]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-120) It is thought that its surface contains [tholins](https://en.wikipedia.org/wiki/Tholin "Tholin"), which are irradiated [organic compounds](https://en.wikipedia.org/wiki/Organic_compound "Organic compound") that are more common in objects in the outer Solar System and can help determine the age of the surface.[[108]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-MattWilliams2017-11-20a-121)[[109]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-MattWilliams2017-11-24a-122) This possibility is inferred from spectroscopic characterization and its reddish color,[[108]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-MattWilliams2017-11-20a-121)[[97]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Fitzsimmons2017a-109) and from the expected effects of interstellar radiation.[[97]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Fitzsimmons2017a-109) Despite the lack of any [cometary coma](https://en.wikipedia.org/wiki/Coma_(cometary) "Coma (cometary)") when it approached the Sun, it may still contain internal ice, hidden by "an insulating mantle produced by long-term [cosmic ray](https://en.wikipedia.org/wiki/Cosmic_ray "Cosmic ray") exposure".[[97]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Fitzsimmons2017a-109)

In November 2019, some astronomers noted that ʻOumuamua may be a "cosmic dust bunny", due to its "very lightweight and 'fluffy' conglomerate of dust and ice grains".[[110]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ES-20191126-123)[[111]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-TAJL-20191111-124)[[112]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-UT-20200908-125)
In August 2020, astronomers reported that ʻOumuamua is not likely to have been composed of frozen [hydrogen](https://en.wikipedia.org/wiki/Hydrogen "Hydrogen"), which had been proposed earlier; the compositional nature of the object continues to be unknown.[[113]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-PHY-20200817-126)[[114]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-AJL-20200817-127)

### Radio measurements

In December 2017, astronomer [Avi Loeb](https://en.wikipedia.org/wiki/Avi_Loeb "Avi Loeb") of [Harvard University](https://en.wikipedia.org/wiki/Harvard_University "Harvard University"), an adviser to the [Breakthrough Listen](https://en.wikipedia.org/wiki/Breakthrough_Listen "Breakthrough Listen") Project, cited ʻOumuamua's unusually elongated shape as one reason the [Green Bank Telescope](https://en.wikipedia.org/wiki/Green_Bank_Telescope "Green Bank Telescope") in [West Virginia](https://en.wikipedia.org/wiki/West_Virginia "West Virginia") would listen for [radio emissions](https://en.wikipedia.org/wiki/Radio_emission "Radio emission") from it to see if there were any unexpected signs that it might be of [artificial origin](https://en.wikipedia.org/wiki/Extraterrestrial_intelligence "Extraterrestrial intelligence"),[[103]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Guarddian2017-12-11-116) although earlier limited observations by other radio telescopes such as the [SETI Institute](https://en.wikipedia.org/wiki/SETI_Institute "SETI Institute")'s [Allen Telescope Array](https://en.wikipedia.org/wiki/Allen_Telescope_Array "Allen Telescope Array") had produced no such results.[[51]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-SETI-54) On 13 December 2017, the Green Bank Telescope observed the object for six hours across four bands of radio frequency. No radio signals from ʻOumuamua were detected in this very limited scanning range, but more observations were planned.[[115]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-128)[[116]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-129)[*[needs update](https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style/Dates_and_numbers#Chronological_items "Wikipedia:Manual of Style/Dates and numbers")*]

## Discussion

### Nitrogen ice theory

Outgassing of [nitrogen ice](https://en.wikipedia.org/wiki/Nitrogen_ice "Nitrogen ice") (N2) could explain why no outgassing was detected. Nitrogen ice the size of ʻOumuamua could survive for 500 million years in the [interstellar medium](https://en.wikipedia.org/wiki/Interstellar_medium "Interstellar medium") and would reflect two-thirds of the Sun's light.[[117]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-130) This explanation has been further supported in March 2021 when scientists presented a theory based on nitrogen ice, and further concluded that ʻOumuamua may be a piece of an [exoplanet](https://en.wikipedia.org/wiki/Exoplanet "Exoplanet") similar to the [dwarf planet](https://en.wikipedia.org/wiki/Dwarf_planet "Dwarf planet") [Pluto](https://en.wikipedia.org/wiki/Pluto "Pluto"), an [exo-Pluto](https://en.wikipedia.org/wiki/Exo-Pluto "Exo-Pluto") as noted, from beyond the [Solar System](https://en.wikipedia.org/wiki/Solar_System "Solar System").[[118]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-PHYS-20210317-131)[[30]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-JGRP-20210316a-33)[[31]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-JGRP-20210316b-34)[[32]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NYT-20210323-35) This theory has been criticized by Loeb.[[119]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-132)[[120]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NS-20211105-133) In November 2021, theoretical studies by Siraj and Loeb hypothesized that ʻOumuamua was not a nitrogen iceberg.[[121]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-LS-20211115-134)[[120]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NS-20211105-133)

### Hydrogen ice theory

It has been proposed that ʻOumuamua contains a significant amount of [hydrogen ice](https://en.wikipedia.org/wiki/Solid_hydrogen "Solid hydrogen").[[122]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ARX-20200526-135)[[123]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NYT-20200615-136) This would point to it originating from the core of an interstellar [molecular cloud](https://en.wikipedia.org/wiki/Molecular_cloud "Molecular cloud"), where conditions for the formation of this material might exist.[[124]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-137) The Sun's heat would cause the hydrogen to [sublime](https://en.wikipedia.org/wiki/Sublimation_(phase_transition) "Sublimation (phase transition)"), which would in turn propel the body. The hydrogen [coma](https://en.wikipedia.org/wiki/Coma_(cometary) "Coma (cometary)") formed by this process would be difficult to detect from Earth-based telescopes, as the atmosphere blocks those wavelengths.[[125]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-usra-138) Regular water-ice comets undergo this as well, however to a much lesser extent and with a visible coma. This may explain the significant non-gravitational acceleration that ʻOumuamua underwent without showing signs of coma formation. Significant mass loss caused by the sublimation would also explain the unusual cigar-like shape, comparable to how a [bar of soap](https://en.wikipedia.org/wiki/Bar_soap "Bar soap") becomes more elongated as it is used up.

However, it was later shown that hydrogen icebergs cannot form out of small grains, and that in order not to evaporate during their journey in interstellar space, they would have had to have been formed about 40 million years ago, in the close neighborhood of the solar system.[[126]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-HoangLoeb2020-06-139)[[127]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-LS-20200819-140)

### Hydrogen-laden water ice theory

In 2023, it was proposed the observed non-gravitational acceleration and spectrum of ʻOumuamua can be best explained by hydrogen outgassing from the water ice matrix. The buildup of the hydrogen in the water ice is expected to happen in the interstellar comets, due to low-temperature water ice [radiolysis](https://en.wikipedia.org/wiki/Radiolysis "Radiolysis") by cosmic ray particles while ʻOumuamua or similar cometary body was in interstellar space.[[128]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-141)[[33]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NAT-20230322-36)

### Hypothetical space missions

Main articles: [Project Lyra](https://en.wikipedia.org/wiki/Project_Lyra "Project Lyra") and [Interstellar object § Hypothetical missions](https://en.wikipedia.org/wiki/Interstellar_object#Hypothetical_missions "Interstellar object")

The [Initiative for Interstellar Studies](https://en.wikipedia.org/wiki/Initiative_for_Interstellar_Studies "Initiative for Interstellar Studies") (i4is) launched [Project Lyra](https://en.wikipedia.org/wiki/Project_Lyra "Project Lyra") to assess the feasibility of a mission to ʻOumuamua.[[129]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ProjectLyra-142) Several options for sending a spacecraft to ʻOumuamua within a time-frame of 5 to 25 years were suggested.[[130]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-UT-20220120-143)[[131]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-AR-2022011-144)[[132]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-145)[[133]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-146) Different mission durations and their velocity requirements were explored with respect to the launch date, assuming direct impulsive transfer to the intercept trajectory.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")*]

The Space Launch System (also being looked at for "interstellar precursor missions") would be even more capable.[[134]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-147)[[135]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-148) Such an interstellar precursor could easily pass by ʻOumuamua on its way out of the Solar System, at speeds of 63 km/s (39 mi/s).[[136]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-149)[[137]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-150)

More advanced options of using solar, laser electric, and laser sail propulsion, based on [Breakthrough Starshot](https://en.wikipedia.org/wiki/Breakthrough_Starshot "Breakthrough Starshot") technology, have also been considered. The challenge is to get to the interstellar object in a reasonable amount of time (and so at a reasonable distance from Earth), and yet be able to gain useful scientific information. To do this, decelerating the spacecraft at ʻOumuamua would be "highly desirable, due to the minimal science return from a hyper-velocity encounter".[[56]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Hein2017-59) If the investigative craft goes too fast, it would not be able to get into orbit or land on the object and would fly past it. The authors conclude that, although challenging, an encounter mission would be feasible using near-term technology.[[56]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-Hein2017-59)[[129]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ProjectLyra-142) Seligman and Laughlin adopt a complementary approach to the Lyra study but also conclude that such missions, though challenging to mount, are both feasible and scientifically attractive.[[138]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ARX-20180412-151)

### Technosignature hypothesis

On 26 October 2018, Loeb and his [post-doctoral researcher](https://en.wikipedia.org/wiki/Postdoctoral_researcher "Postdoctoral researcher"), Shmuel Bialy, submitted a paper exploring the possibility of ʻOumuamua being an artificial thin [solar sail](https://en.wikipedia.org/wiki/Solar_sail "Solar sail")[[139]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-152)[[140]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-CT-20190204-153) accelerated by [solar radiation](https://en.wikipedia.org/wiki/Solar_radiation "Solar radiation") pressure, in an effort to help explain the object's comet-like non-gravitational acceleration.[[74]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-UT-230181031-83)[[75]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ARX-20181101-84)[[141]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-SA-201809287-154) Other scientists have stated that the available evidence is insufficient to consider such a premise,[[142]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-155)[[143]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-156)[[144]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-157) and that a tumbling solar sail would not be able to accelerate.[[145]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-158) In response, Loeb wrote an article detailing six anomalous properties of ʻOumuamua that make it unusual, unlike any comets or asteroids seen before 2018, and published a  [public science book](https://en.wikipedia.org/wiki/Extraterrestrial:_The_First_Sign_of_Intelligent_Life_Beyond_Earth "Extraterrestrial: The First Sign of Intelligent Life Beyond Earth") in 2021 about the state of the discussion.[[146]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-SA-20181120-159)[[147]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-TNY-20190116-160) The solar sail [technosignature](https://en.wikipedia.org/wiki/Technosignature "Technosignature") hypothesis is considered unlikely by many experts owing to [available simpler explanations](https://en.wikipedia.org/wiki/Occam's_razor "Occam's razor") that align with the expected characteristics of interstellar asteroids and comets.[[148]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-MD-20230718-161)[[127]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-LS-20200819-140)[[149]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-162)

### Other interstellar objects

Main article: [Interstellar object](https://en.wikipedia.org/wiki/Interstellar_object "Interstellar object")

[2I/Borisov](https://en.wikipedia.org/wiki/2I/Borisov "2I/Borisov") was discovered on 30 August 2019, and was soon confirmed to be an interstellar comet. Arriving from the direction of [Cassiopeia](https://en.wikipedia.org/wiki/Cassiopeia_(constellation) "Cassiopeia (constellation)"), the object arrived at perihelion (closest point to the Sun) on 8 December 2019.

[3I/ATLAS](https://en.wikipedia.org/wiki/3I/ATLAS "3I/ATLAS") was discovered on 1 July 2025. It arrived with a [hyperbolic excess velocity](https://en.wikipedia.org/wiki/Hyperbolic_trajectory#Parameters_describing_a_hyperbolic_trajectory "Hyperbolic trajectory") of 58 km/s.

Other proposed interstellar objects include the meteors [CNEOS 2014-01-08](https://en.wikipedia.org/wiki/CNEOS_2014-01-08 "CNEOS 2014-01-08")[[150]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-SPC-20221103-163) and [CNEOS 2017-03-09](https://en.wikipedia.org/wiki/CNEOS_2017-03-09 "CNEOS 2017-03-09") that impacted Earth in 2014[[151]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-VICE-202209407-164)[[152]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-INV-20220411-165)[[153]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-ARX-20190604-166)[[154]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NASA-20220408-167) and 2017, respectively,[[155]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-TDB-20220923-168) although these claims have been met with skepticism.[[156]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-NYT-20240311-169)

## See also

* [C/1980 E1 (Bowell)](https://en.wikipedia.org/wiki/C/1980_E1_(Bowell) "C/1980 E1 (Bowell)") – the most eccentric comet known in the Solar System with an eccentricity of 1.057
* [514107 Kaʻepaokaʻāwela](https://en.wikipedia.org/wiki/514107_Kaʻepaokaʻāwela "514107 Kaʻepaokaʻāwela"), an asteroid of possible interstellar origin
* [C/2017 U7](https://en.wikipedia.org/wiki/C/2017_U7_(PanSTARRS) "C/2017 U7 (PanSTARRS)"), a non-interstellar hyperbolic comet discovered 10 days after ʻOumuamua, announced in March 2018
* [C/2018 C2](https://en.wikipedia.org/wiki/C/2018_C2_(Lemmon) "C/2018 C2 (Lemmon)"), another non-interstellar hyperbolic comet, announced in March 2018
* *[Extraterrestrial: The First Sign of Intelligent Life Beyond Earth](https://en.wikipedia.org/wiki/Extraterrestrial:_The_First_Sign_of_Intelligent_Life_Beyond_Earth "Extraterrestrial: The First Sign of Intelligent Life Beyond Earth")*, a 2021 book by Avi Loeb describing the ʻOumuamua technosignature hypothesis
* *[Rendezvous with Rama](https://en.wikipedia.org/wiki/Rendezvous_with_Rama "Rendezvous with Rama")*, a 1973 Arthur C. Clarke science-fiction novel about intercepting a large cylindrical spacecraft transiting the Solar System
* [3I/ATLAS](https://en.wikipedia.org/wiki/3I/ATLAS "3I/ATLAS"), the third interstellar comet discovered in 2025 in the Solar System

## Notes

1. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-2) 5-minute exposure taken by the [William Herschel Telescope](https://en.wikipedia.org/wiki/William_Herschel_Telescope "William Herschel Telescope") on 28 October; ʻOumuamua appears as a light source in the center of the image, while background stars appear streaked due to the speed of ʻOumuamua as the telescope tracked it.[[1]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-apod-1-1)
2. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-11) Objects on hyperbolic trajectories have negative semimajor axis, giving them a positive orbital energy.
3. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-25) Range at which the object was expected to be observable. Brightness peaked at 19.7 mag on 18 October 2017, and faded below 27.5 mag (the limit of [Hubble Space Telescope](https://en.wikipedia.org/wiki/Hubble_Space_Telescope "Hubble Space Telescope") for fast-moving objects) around 1 January 2018. By late 2019, it should have dimmed to 34 mag.
4. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-61) For comparison, comet C/1980 E1 will only be moving 4.2 km/s when it is 500 AU from the Sun.
5. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-64) The solar [escape velocity](https://en.wikipedia.org/wiki/Earth_escape_velocity "Earth escape velocity") from Earth's orbit (1 AU from the Sun) is 42.1 km/s.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")*][*[original research?](https://en.wikipedia.org/wiki/Wikipedia:No_original_research "Wikipedia:No original research")*] For comparison, even [1P/Halley](https://en.wikipedia.org/wiki/1P/Halley "1P/Halley") moves at 41.5 km/s when 1 AU from the Sun, according to the formula *v* = 42.1219 √1/*r* − 0.5/*a*, where *r* is the distance from the Sun, and *a* is the major semi-axis. Near-Earth asteroid [2062 Aten](https://en.wikipedia.org/wiki/2062_Aten "2062 Aten") only moves at 29 km/s when 1 AU from the Sun because of the much smaller semi-major axis.
6. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-70) Unlike ʻOumuamua, C/1980 E1's orbit got its high eccentricity of 1.057 due to a close encounter with [Jupiter](https://en.wikipedia.org/wiki/Jupiter "Jupiter"). Its inbound-orbit eccentricity was less than 1.[[54]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-skyandtelescope-57)
7. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-73) Orbits computed with only a handful of observations can be unreliable. Short arcs can result in computer generated orbits rejecting some data unnecessarily.
8. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-81) Comet [C/2012 S1 (ISON)](https://en.wikipedia.org/wiki/C/2012_S1_(ISON) "C/2012 S1 (ISON)") peaked at 377 km/s (1,360,000 km/h) at perihelion[[73]](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_note-80) because it passed 0.0124 AU from the Sun (20 times closer than ʻOumuamua).
9. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-82) According to the formula: [2

   θ


   ∞
   =
   2

   cos

   −
   1
   ⁡
   (
   −
   1

   /
   e
   )
   {\textstyle 2\,\theta {_{\infty }}=2\cos ^{-1}(-1/e)}
   ![{\textstyle 2\,\theta {_{\infty }}=2\cos ^{-1}(-1/e)}](https://wikimedia.org/api/rest_v1/media/math/render/svg/b99a22d49d9dd85c7e73b9aad2723dda8437415b)](https://en.wikipedia.org/wiki/Hyperbolic_trajectory#Eccentricity_and_angle_between_approach_and_departure "Hyperbolic trajectory")
10. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-93) This is true for the nominal position of the star. However, its actual distance is not known precisely: According to [Gaia Data Release 1](https://en.wikipedia.org/wiki/Gaia_Data_Release_1 "Gaia Data Release 1"), the distance to TYC4742-1027-1 is 137 ± 13 [parsecs](https://en.wikipedia.org/wiki/Parsec "Parsec") (447 ± 42 [light-years](https://en.wikipedia.org/wiki/Light-year "Light-year")). It is not known if an encounter actually occurred. Update: This star has new measurements in [Gaia Data Release 2](https://en.wikipedia.org/wiki/Gaia_Data_Release_2 "Gaia Data Release 2"), and an origins study based on this by Bailer-Jones et al. (2018) shows that TYC4742-1027-1 did not come within 2 pc of ʻOumuamua.
11. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-101) See also Ravikov, Roman R. (2018). ["1I/2017 ʻOumuamua-like Interstellar Asteroids as Possible Messengers from Dead Stars"](https://doi.org/10.3847%2F1538-4357%2Faac5ef). *The Astrophysical Journal*. **861** (1): 35. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1801.02658](https://arxiv.org/abs/1801.02658). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018ApJ...861...35R](https://ui.adsabs.harvard.edu/abs/2018ApJ...861...35R). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/1538-4357/aac5ef](https://doi.org/10.3847%2F1538-4357%2Faac5ef).. ʻOumuamua is a fragment of a white-dwarf-star tidal-disruption-event. This easily explains its 6:1 or 10:1 elongation and its "refractory" composition; containing probably nickel-iron, possibly other metals, too.
12. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-104) According to [Central Bureau for Astronomical Telegrams](https://en.wikipedia.org/wiki/Central_Bureau_for_Astronomical_Telegrams "Central Bureau for Astronomical Telegrams")'s CBET 4450, none of the observers had detected any sign of cometary activity. The initial classification as a comet was based on the object's orbit.
13. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-112) [1865 Cerberus](https://en.wikipedia.org/wiki/1865_Cerberus "1865 Cerberus") has a lightcurve amplitude of 2.3 magnitudes.

## References

1. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-apod-1_1-0) Bonnell, Jerry; [Nemiroff, Robert](https://en.wikipedia.org/wiki/Robert_J._Nemiroff "Robert J. Nemiroff") (3 November 2017). ["A/2017 U1: An Interstellar Visitor"](https://apod.nasa.gov/apod/ap171103.html). *[Astronomy Picture of the Day](https://en.wikipedia.org/wiki/Astronomy_Picture_of_the_Day "Astronomy Picture of the Day")*. [Archived](https://web.archive.org/web/20190313070147/https://apod.nasa.gov/apod/ap171103.html) from the original on 13 March 2019. Retrieved 13 March 2019. "A point of light centered in this 5 minute exposure recorded with the William Herschel Telescope in the Canary Islands on October 28 ... Faint background stars appear streaked because the massive 4.2 meter diameter telescope is tracking the rapidly moving A/2017 U1 in the field of view."
2. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NASA171026_3-0) ["Small Asteroid or Comet 'Visits' from Beyond the Solar System"](https://www.nasa.gov/feature/jpl/small-asteroid-or-comet-visits-from-beyond-the-solar-system). [NASA](https://en.wikipedia.org/wiki/NASA "NASA"). 26 October 2017. [Archived](https://web.archive.org/web/20171202092239/https://www.nasa.gov/feature/jpl/small-asteroid-or-comet-visits-from-beyond-the-solar-system/) from the original on 2 December 2017. Retrieved 29 October 2017.
3. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Discovery_4-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Discovery_4-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Discovery_4-2) ["MPEC 2017-U181: COMET C/2017 U1 (PANSTARRS)"](http://www.minorplanetcenter.net/mpec/K17/K17UI1.html). *[Minor Planet Center](https://en.wikipedia.org/wiki/Minor_Planet_Center "Minor Planet Center")*. [International Astronomical Union](https://en.wikipedia.org/wiki/International_Astronomical_Union "International Astronomical Union"). 25 October 2017. [Archived](https://web.archive.org/web/20171025184710/http://www.minorplanetcenter.net/mpec/K17/K17UI1.html) from the original on 25 October 2017. Retrieved 25 October 2017. (CK17U010)
4. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-MPEC2017-V17_5-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-MPEC2017-V17_5-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-MPEC2017-V17_5-2) [4](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-MPEC2017-V17_5-3) [5](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-MPEC2017-V17_5-4) [6](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-MPEC2017-V17_5-5) ["MPEC 2017-V17: New Designation Scheme for Interstellar Objects"](http://www.minorplanetcenter.net/mpec/K17/K17V17.html). *Minor Planet Center*. International Astronomical Union. 6 November 2017. [Archived](https://web.archive.org/web/20200108040032/https://www.minorplanetcenter.net/mpec/K17/K17V17.html) from the original on 8 January 2020. Retrieved 6 November 2017.
5. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-A2017U1_6-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-A2017U1_6-1) ["MPEC 2017-U183: A/2017 U1"](http://www.minorplanetcenter.net/mpec/K17/K17UI3.html). *Minor Planet Center*. International Astronomical Union. 25 October 2017. [Archived](https://web.archive.org/web/20171026054257/http://www.minorplanetcenter.net/mpec/K17/K17UI3.html) from the original on 26 October 2017. Retrieved 25 October 2017. (AK17U010)
6. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-spectrum_7-0) Antier, K. (30 October 2017). ["A/2017 U1, first interstellar asteroid ever detected!"](https://www.imo.net/a2017-u1-first-interstellar-asteroid-ever-detected/). *International Meteor Organization*. [Archived](https://web.archive.org/web/20171107004829/https://www.imo.net/a2017-u1-first-interstellar-asteroid-ever-detected/) from the original on 7 November 2017. Retrieved 7 November 2017.
7. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-jpldata_8-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-jpldata_8-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-jpldata_8-2) [4](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-jpldata_8-3) [5](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-jpldata_8-4) [6](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-jpldata_8-5) ["JPL Small-Body Database Browser: ʻOumuamua (A/2017 U1)"](https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1I&view=OPC). *[JPL Small-Body Database](https://en.wikipedia.org/wiki/JPL_Small-Body_Database "JPL Small-Body Database")*. [Jet Propulsion Laboratory](https://en.wikipedia.org/wiki/Jet_Propulsion_Laboratory "Jet Propulsion Laboratory"). [Archived](https://web.archive.org/web/20210121065013/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1I) from the original on 21 January 2021. Retrieved 19 March 2021.  
   JPL 1 (Solution date: 2017-Oct-24)  
   JPL 10 (Solution date: 2017-Nov-03)  
   JPL 14 (Solution date: 2017-Nov-21)  
   JPL 16 (Solution date: 2018-Jun-26)
8. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-ARX-20180920_9-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-ARX-20180920_9-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-ARX-20180920_9-2) Rafikov, Roman R. (20 September 2018). "Spin Evolution and Cometary Interpretation of the Interstellar Minor Object 1I/2017 ʻOumuamua". [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1809.06389v2](https://arxiv.org/abs/1809.06389v2) [[astro-ph.EP](https://arxiv.org/archive/astro-ph.EP)].
9. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-QM-20181010_10-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-QM-20181010_10-1) Skibba, Ramin (10 October 2018). ["Interstellar Visitor Found to Be Unlike a Comet or an Asteroid"](https://www.quantamagazine.org/interstellar-comet-oumuamua-might-not-actually-be-a-comet-20181010/). *[Quanta Magazine](https://en.wikipedia.org/wiki/Quanta_Magazine "Quanta Magazine")*. [Archived](https://web.archive.org/web/20200427010524/https://www.quantamagazine.org/interstellar-comet-oumuamua-might-not-actually-be-a-comet-20181010/) from the original on 27 April 2020. Retrieved 10 October 2018.
10. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-pseudoMPEC_12-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-pseudoMPEC_12-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-pseudoMPEC_12-2) [4](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-pseudoMPEC_12-3) [5](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-pseudoMPEC_12-4) [6](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-pseudoMPEC_12-5) [7](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-pseudoMPEC_12-6) [8](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-pseudoMPEC_12-7) [9](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-pseudoMPEC_12-8) ["Pseudo-MPEC for A/2017 U1 (FAQ File)"](https://projectpluto.com/temp/2017u1.htm). Bill Gray of Project Pluto. 26 October 2017. [Archived](https://web.archive.org/web/20171026214746/https://projectpluto.com/temp/2017u1.htm) from the original on 26 October 2017. Retrieved 26 October 2017. [(Orbital elements)](https://projectpluto.com/temp/2017u1_a.htm#elements) [Archived](https://web.archive.org/web/20180930231741/https://projectpluto.com/temp/2017u1_a.htm#elements) 30 September 2018 at the [Wayback Machine](https://en.wikipedia.org/wiki/Wayback_Machine "Wayback Machine")
11. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Maschenko2019-09_13-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Maschenko2019-09_13-1) Mashchenko, S. (2019). ["Modeling the light curve of ʻOumuamua: evidence for torque and disc-like shape"](https://doi.org/10.1093%2Fmnras%2Fstz2380). *Monthly Notices of the Royal Astronomical Society*. **489** (3): 3003–3021. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1906.03696](https://arxiv.org/abs/1906.03696). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2019MNRAS.489.3003M](https://ui.adsabs.harvard.edu/abs/2019MNRAS.489.3003M). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1093/mnras/stz2380](https://doi.org/10.1093%2Fmnras%2Fstz2380). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [182952355](https://api.semanticscholar.org/CorpusID:182952355).
12. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-JewittSeligman2022_14-0) Jewitt, D.; Seligman, D. (2023). "Interstellar Interlopers". *Annual Review of Astronomy and Astrophysics*. **61**: 197. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[2209.08182](https://arxiv.org/abs/2209.08182). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2023ARA&A..61..197J](https://ui.adsabs.harvard.edu/abs/2023ARA&A..61..197J). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1146/annurev-astro-071221-054221](https://doi.org/10.1146%2Fannurev-astro-071221-054221).
13. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NASA20181114_15-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NASA20181114_15-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NASA20181114_15-2) Cofield, Calia (14 November 2018). ["NASA Learns More About Interstellar Visitor ʻOumuamua"](https://www.jpl.nasa.gov/news/news.php?feature=7280). *[NASA](https://en.wikipedia.org/wiki/NASA "NASA")*. [Archived](https://web.archive.org/web/20200415092634/https://www.jpl.nasa.gov/news/news.php?feature=7280) from the original on 15 April 2020. Retrieved 14 November 2018.
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17. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NOAO2017_19-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NOAO2017_19-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NOAO2017_19-2) [4](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NOAO2017_19-3) [5](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NOAO2017_19-4) ["A Familiar-Looking Messenger from Another Solar System"](https://www.noao.edu/news/2017/pr1706.php) (Press release). National Optical Astronomy Observatory. 15 November 2017. NOAO 17-06. [Archived](https://web.archive.org/web/20171116133909/https://www.noao.edu/news/2017/pr1706.php) from the original on 16 November 2017. Retrieved 15 November 2017.
18. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Fraser2018a_20-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Fraser2018a_20-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Fraser2018a_20-2) [4](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Fraser2018a_20-3) Fraser, W. C.; Pravec, P.; Fitzsimmons, A.; Lacerda, P.; Bannister, M. T.; Snodgrass, C.; Smolić, I. (9 February 2018). ["The tumbling rotational state of 1I/ʻOumuamua"](https://pure.qub.ac.uk/portal/en/publications/the-tumbling-rotational-state-of-1ioumuamua(cbcc0793-72c1-4f42-b78a-5bcdeff6274c).html). *Nature Astronomy*. **2** (5): 383–386. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1711.11530](https://arxiv.org/abs/1711.11530). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018NatAs...2..383F](https://ui.adsabs.harvard.edu/abs/2018NatAs...2..383F). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1038/s41550-018-0398-z](https://doi.org/10.1038%2Fs41550-018-0398-z). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [119353074](https://api.semanticscholar.org/CorpusID:119353074). [Archived](https://web.archive.org/web/20180903215215/https://pure.qub.ac.uk/portal/en/publications/the-tumbling-rotational-state-of-1ioumuamua(cbcc0793-72c1-4f42-b78a-5bcdeff6274c).html) from the original on 3 September 2018. Retrieved 3 September 2018.
19. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bolin2017_21-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bolin2017_21-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bolin2017_21-2) [4](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bolin2017_21-3) Bolin, B.T.; et al. (2017). ["APO Time Resolved Color Photometry of Highly-Elongated Interstellar Object 1I/ʻOumuamua"](https://doi.org/10.3847%2F2041-8213%2Faaa0c9). *The Astrophysical Journal*. **852** (1): L2. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1711.04927](https://arxiv.org/abs/1711.04927). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018ApJ...852L...2B](https://ui.adsabs.harvard.edu/abs/2018ApJ...852L...2B). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2041-8213/aaa0c9](https://doi.org/10.3847%2F2041-8213%2Faaa0c9). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [118894742](https://api.semanticscholar.org/CorpusID:118894742).
20. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bannister2017_22-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bannister2017_22-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bannister2017_22-2) [4](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bannister2017_22-3) [5](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bannister2017_22-4) [6](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bannister2017_22-5) [7](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bannister2017_22-6) [8](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bannister2017_22-7) [9](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bannister2017_22-8) Bannister, M.T.; Schwamb, M.E. (2017). ["Col-OSSOS: Colors of the Interstellar Planetesimal 1I/2017 U1 in Context with the Solar System"](https://doi.org/10.3847%2F2041-8213%2Faaa07c). *The Astrophysical Journal*. **851** (2): L38. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1711.06214](https://arxiv.org/abs/1711.06214). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2017ApJ...851L..38B](https://ui.adsabs.harvard.edu/abs/2017ApJ...851L..38B). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2041-8213/aaa07c](https://doi.org/10.3847%2F2041-8213%2Faaa07c). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [56264680](https://api.semanticscholar.org/CorpusID:56264680). "As its albedo is unknown, we do not describe 1I/ʻOumuamua as consistent with Tholen (1984) P type."
21. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Feng2017_23-0) Feng, F. & Jones, H. R. A. (23 November 2017). ["ʻOumuamua as a messenger from the Local Association"](https://doi.org/10.3847%2F2041-8213%2Faaa404). *The Astrophysical Journal*. **852** (2): L27. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1711.08800](https://arxiv.org/abs/1711.08800). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018ApJ...852L..27F](https://ui.adsabs.harvard.edu/abs/2018ApJ...852L..27F). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2041-8213/aaa404](https://doi.org/10.3847%2F2041-8213%2Faaa404). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [56197486](https://api.semanticscholar.org/CorpusID:56197486).
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23. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-26) Osborne, Hannah (16 April 2019). ["First meteor of interstellar origin discovered by scientists"](https://www.newsweek.com/first-interstellar-meteor-discovered-1397886). *Newsweek*. Retrieved 11 April 2022.
24. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-SLN-20190312_27-0) Carlisle, Camille M. (12 March 2019). ["ʻOumuamua sped up as it left the inner solar system. This may be why – Astronomers think a jet-powered rocking motion could solve the puzzle"](https://www.salon.com/2019/03/12/oumuamua-sped-up-as-it-left-the-inner-solar-system-this-might-be-why_partner/). *[Salon](https://en.wikipedia.org/wiki/Salon_(website) "Salon (website)")*. [Archived](https://web.archive.org/web/20200319173919/https://www.salon.com/2019/03/12/oumuamua-sped-up-as-it-left-the-inner-solar-system-this-might-be-why_partner/) from the original on 19 March 2020. Retrieved 12 March 2019.
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28. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-UT-20190201_31-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-UT-20190201_31-1) Williams, Matt (1 February 2019). ["Oumuamua Could be the Debris Cloud of a Disintegrated Interstellar Comet"](https://www.universetoday.com/141398/oumuamua-could-be-the-debris-cloud-of-a-disintegrated-interstellar-comet/#more-141398). *[Universe Today](https://en.wikipedia.org/wiki/Universe_Today "Universe Today")*. [Archived](https://web.archive.org/web/20190203030346/https://www.universetoday.com/141398/oumuamua-could-be-the-debris-cloud-of-a-disintegrated-interstellar-comet/#more-141398) from the original on 3 February 2019. Retrieved 2 February 2019.
29. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-ARX-20190201_32-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-ARX-20190201_32-1) Sekanina, Zdenek (31 January 2019). "1I/ʻOumuamua As Debris Of Dwarf Interstellar Comet That Disintegrated Before Perihelion". [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1901.08704](https://arxiv.org/abs/1901.08704) [[astro-ph.EP](https://arxiv.org/archive/astro-ph.EP)].
30. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-JGRP-20210316a_33-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-JGRP-20210316a_33-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-JGRP-20210316a_33-2) Jackson, Alan P.; et al. (16 March 2021). ["1I/ʻOumuamua as an N2 ice fragment of an exo-Pluto surface: I. Size and Compositional Constraints"](https://doi.org/10.1029%2F2020JE006706). *[Journal of Geophysical Research: Planets](https://en.wikipedia.org/wiki/Journal_of_Geophysical_Research:_Planets "Journal of Geophysical Research: Planets")*. **126** (5) e2020JE006706. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[2103.08788](https://arxiv.org/abs/2103.08788). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2021JGRE..12606706J](https://ui.adsabs.harvard.edu/abs/2021JGRE..12606706J). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1029/2020JE006706](https://doi.org/10.1029%2F2020JE006706).
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32. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NYT-20210323_35-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NYT-20210323_35-1) [Overbye, Dennis](https://en.wikipedia.org/wiki/Dennis_Overbye "Dennis Overbye") (23 March 2021). ["Why Oumuamua, the Interstellar Visitor, Looks Eerily Familiar – A piece of an extrasolar Pluto may have passed through our cosmic neighborhood, a new study suggests"](https://www.nytimes.com/2021/03/23/science/astronomy-oumuamua-comet.html). *[The New York Times](https://en.wikipedia.org/wiki/The_New_York_Times "The New York Times")*. Retrieved 23 March 2021.
33. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NAT-20230322_36-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NAT-20230322_36-1) Bergner, Jennifer; Seligman, Darryl Z. (22 March 2023). ["Acceleration of 1I/ʻOumuamua from radiolytically produced H2 in H2O ice"](https://www.nature.com/articles/s41586-022-05687-w). *[Nature](https://en.wikipedia.org/wiki/Nature_(journal) "Nature (journal)")*. **615** (7953): 610–613. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[2303.13698](https://arxiv.org/abs/2303.13698). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1038/s41586-022-05687-w](https://doi.org/10.1038%2Fs41586-022-05687-w). [PMID](https://en.wikipedia.org/wiki/PMID_(identifier) "PMID (identifier)") [36949336](https://pubmed.ncbi.nlm.nih.gov/36949336). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [257668585](https://api.semanticscholar.org/CorpusID:257668585). Retrieved 23 March 2023.
34. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NYT-20230322_37-0) [Overbye, Dennis](https://en.wikipedia.org/wiki/Dennis_Overbye "Dennis Overbye") (22 March 2023). ["Oumuamua Was a Comet After All, a Study Suggests – Astronomers offer 'a surprisingly simple explanation' for the curious behavior of the interstellar visitor in 2017"](https://www.nytimes.com/2023/03/22/science/astronomy-oumuamua-comet.html). *[The New York Times](https://en.wikipedia.org/wiki/The_New_York_Times "The New York Times")*. Retrieved 23 March 2023.
35. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-38) NASA (29 September 2025). ["animation"](https://photojournal.jpl.nasa.gov/archive/PIA22357_JPL-20180620-ASTRDSf-0007-Interstellar%20Asteroid%20animation-720p.mp4).
36. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Pukui-Elbert_39-0) Pukui, M.K.; Elbert, S.H. (2003). ["Hawaiian Dictionary"](http://wehewehe.org/gsdl2.85/cgi-bin/hdict?e=q-11000-00---off-0hdict--00-1----0-10-0---0---0direct-10-ED--4-------0-1lp0--11-en-Zz-1---Zz-1-home-%CA%BBoumuamua--00-3-1-00-0--4----0-0-11-00-0utfZz-8-00&a=d&d=D15888). *Ulukau: Hawaiian Electronic Library*. University of Hawaiʻi Press. [Archived](https://web.archive.org/web/20210201045614/http://wehewehe.org/gsdl2.85/cgi-bin/hdict?e=q-11000-00---off-0hdict--00-1----0-10-0---0---0direct-10-ED--4-------0-1lp0--11-en-Zz-1---Zz-1-home-%CA%BBoumuamua--00-3-1-00-0--4----0-0-11-00-0utfZz-8-00&a=d&d=D15888) from the original on 1 February 2021. Retrieved 21 November 2017.
37. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Outerplaces_40-0) Kesh, Johnathan (8 November 2017). ["Our Solar System's First Interstellar Asteroid is Named ʻOumuamua'"](https://www.outerplaces.com/science/item/17035-interstellar-object-asteroid-oumuamua). *Outer Places*. [Archived](https://web.archive.org/web/20171201032243/https://www.outerplaces.com/science/item/17035-interstellar-object-asteroid-oumuamua) from the original on 1 December 2017. Retrieved 23 November 2017.
38. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-41) Wall, Mike (16 November 2017). ["Meet ʻOumuamua, the First-Ever Asteroid from Another Star"](http://www.scientificamerican.com/article/meet-oumuamua-the-first-ever-asteroid-from-another-star). *Scientific American*. [Archived](https://web.archive.org/web/20171122224917/https://www.scientificamerican.com/article/meet-oumuamua-the-first-ever-asteroid-from-another-star/) from the original on 22 November 2017. Retrieved 24 November 2017 – via Space.com.
39. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-42) Gal, Roy (20 November 2017). ["An interstellar visitor unmasked"](http://www.hawaii.edu/news/2017/11/20/an-interstellar-visitor-unmasked). *University of Hawaiʻi System News*. [Archived](https://web.archive.org/web/20171124124145/http://www.hawaii.edu/news/2017/11/20/an-interstellar-visitor-unmasked/) from the original on 24 November 2017. Retrieved 22 November 2017.
40. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-43) ["The first visitor from another solar system has just been spotted: Rendezvous with Rama?"](https://www.economist.com/news/science-and-technology/21730863-rendezvous-rama-first-visitor-another-solar-system-has-just-been). *The Economist*. 2 November 2017. [Archived](https://web.archive.org/web/20171206212306/https://www.economist.com/news/science-and-technology/21730863-rendezvous-rama-first-visitor-another-solar-system-has-just-been) from the original on 6 December 2017. Retrieved 6 December 2017.
41. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-44) [Morrison, David](https://en.wikipedia.org/wiki/David_Morrison_(astrophysicist) "David Morrison (astrophysicist)") (March–April 2018). "Interstellar Visitor: The Strange Asteroid from a Faraway System". *Skeptical Inquirer*. **42** (2): 9.
42. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Gemini_45-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Gemini_45-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Gemini_45-2) ["First Known Interstellar Visitor is an 'Oddball'"](http://www.gemini.edu/node/12729). *Gemini Observatory* (Press release). 20 November 2017. [Archived](https://web.archive.org/web/20171123071154/http://www.gemini.edu/node/12729) from the original on 23 November 2017. Retrieved 28 November 2017.
43. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NAT-20171120_46-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NAT-20171120_46-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NAT-20171120_46-2) [4](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NAT-20171120_46-3) [5](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NAT-20171120_46-4) Meech, K.J.; et al. (20 November 2017). ["A brief visit from a red and extremely elongated interstellar asteroid"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8979573). *[Nature](https://en.wikipedia.org/wiki/Nature_(journal) "Nature (journal)")*. **552** (7685): 378–381. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2017Natur.552..378M](https://ui.adsabs.harvard.edu/abs/2017Natur.552..378M). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1038/nature25020](https://doi.org/10.1038%2Fnature25020). [PMC](https://en.wikipedia.org/wiki/PMC_(identifier) "PMC (identifier)") [8979573](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8979573). [PMID](https://en.wikipedia.org/wiki/PMID_(identifier) "PMID (identifier)") [29160305](https://pubmed.ncbi.nlm.nih.gov/29160305). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [4393243](https://api.semanticscholar.org/CorpusID:4393243).
44. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Rincon2017_47-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Rincon2017_47-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Rincon2017_47-2) [4](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Rincon2017_47-3) Rincon, Paul (20 November 2017). ["Bizarre shape of interstellar asteroid"](https://www.bbc.com/news/science-environment-42053634). *BBC News*. [Archived](https://web.archive.org/web/20200408062702/https://www.bbc.com/news/science-environment-42053634) from the original on 8 April 2020. Retrieved 20 November 2017.
45. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-jpl-news_48-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-jpl-news_48-1) ["Solar System's First Interstellar Visitor Dazzles Scientists"](https://www.jpl.nasa.gov/news/news.php?feature=7006). *Jet Propulsion Laboratory*. 20 November 2017. [Archived](https://web.archive.org/web/20200310024611/https://www.jpl.nasa.gov/news/news.php?feature=7006) from the original on 10 March 2020. Retrieved 20 December 2017.
46. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-MPC-object_49-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-MPC-object_49-1) ["1I/ʻOumuamua = A/2017 U1 Orbit"](https://www.minorplanetcenter.net/db_search/show_object?object_id=1I). *Minor Planet Center*. International Astronomical Union. [Archived](https://web.archive.org/web/20180104073303/https://www.minorplanetcenter.net/db_search/show_object?object_id=1I) from the original on 4 January 2018. Retrieved 9 November 2017.
47. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Koren-20171211_50-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Koren-20171211_50-1) Koren, Marina (11 December 2017). ["Astronomers to Check Mysterious Interstellar Object for Signs of Technology"](https://www.theatlantic.com/science/archive/2017/12/yuri-milner-oumuamua-interstellar-asteroid/547985/). The Atlantic. [Archived](https://web.archive.org/web/20171211201521/https://www.theatlantic.com/science/archive/2017/12/yuri-milner-oumuamua-interstellar-asteroid/547985/) from the original on 11 December 2017. Retrieved 11 December 2017.
48. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-wenz2017_51-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-wenz2017_51-1) Wenz, John (22 November 2017). ["The first discovered interstellar asteroid is a quarter-mile long red beast"](http://www.astronomy.com/news/2017/11/interstellar-asteroid-is-a-quarter-mile-long-red-beast). *Astronomy*. [Archived](https://web.archive.org/web/20190604023605/http://www.astronomy.com/news/2017/11/interstellar-asteroid-is-a-quarter-mile-long-red-beast) from the original on 4 June 2019. Retrieved 6 December 2017.
49. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NYT-20171122_52-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NYT-20171122_52-1) [Overbye, Dennis](https://en.wikipedia.org/wiki/Dennis_Overbye "Dennis Overbye") (22 November 2017). ["An Interstellar Visitor Both Familiar and Alien"](https://www.nytimes.com/2017/11/22/science/oumuamua-space-asteroid.html). *[The New York Times](https://en.wikipedia.org/wiki/The_New_York_Times "The New York Times")*. [Archived](https://web.archive.org/web/20200417202638/https://www.nytimes.com/2017/11/22/science/oumuamua-space-asteroid.html) from the original on 17 April 2020. Retrieved 23 November 2017.
50. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-53) Shostak, Seth (14 December 2017). ["Is this mysterious space rock actually an alien spaceship?"](https://www.nbcnews.com/mach/science/mysterious-space-rock-actually-alien-spaceship-ncna829501). *[NBC News](https://en.wikipedia.org/wiki/NBC_News "NBC News")*. [Archived](https://web.archive.org/web/20171219145459/https://www.nbcnews.com/mach/science/mysterious-space-rock-actually-alien-spaceship-ncna829501) from the original on 19 December 2017. Retrieved 20 December 2017.
51. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-SETI_54-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-SETI_54-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-SETI_54-2) Billings, Lee (11 December 2017). ["Alien Probe or Galactic Driftwood? SETI Tunes In to ʻOumuamua"](https://www.scientificamerican.com/article/alien-probe-or-galactic-driftwood-seti-tunes-in-to-oumuamua/). *[Scientific American](https://en.wikipedia.org/wiki/Scientific_American "Scientific American")*. [Archived](https://web.archive.org/web/20171214003318/https://www.scientificamerican.com/article/alien-probe-or-galactic-driftwood-seti-tunes-in-to-oumuamua/) from the original on 14 December 2017. Retrieved 12 December 2017. "So far limited observations of ʻOumuamua, using facilities such as the SETI Institute's Allen Telescope Array, have turned up nothing."
52. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-55) Beall, Abigail (12 December 2017). ["It isn't an alien spacecraft, but we should still study ʻOumuamua"](https://www.wired.co.uk/article/oumuamua-is-not-an-interstellar-spacecraft). *Wired UK*. [Archived](https://web.archive.org/web/20171212163216/http://www.wired.co.uk/article/oumuamua-is-not-an-interstellar-spacecraft) from the original on 12 December 2017. Retrieved 12 December 2017.
53. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-No_narrowband_signals_found._56-0) Enriquez, J. E. (9 January 2018). ["Breakthrough Listen Observations of 1I/ʻOumuamua with the GBT"](https://doi.org/10.3847%2F2515-5172%2Faaa6c9). *Research Notes of the American Astronomical Society*. **2** (1): 9. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1801.02814](https://arxiv.org/abs/1801.02814). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018RNAAS...2....9E](https://ui.adsabs.harvard.edu/abs/2018RNAAS...2....9E). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2515-5172/aaa6c9](https://doi.org/10.3847%2F2515-5172%2Faaa6c9). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [119435272](https://api.semanticscholar.org/CorpusID:119435272).
54. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-skyandtelescope_57-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-skyandtelescope_57-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-skyandtelescope_57-2) [4](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-skyandtelescope_57-3) [5](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-skyandtelescope_57-4) Beatty, Kelly (25 October 2017). ["Astronomers Spot First-Known Interstellar Comet"](http://www.skyandtelescope.com/astronomy-news/astronomers-spot-first-known-interstellar-comet/). Sky & Telescope. [Archived](https://wayback.archive-it.org/all/20171026001610/http://www.skyandtelescope.com/astronomy-news/astronomers-spot-first-known-interstellar-comet/) from the original on 26 October 2017. Retrieved 25 October 2017.
55. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-58) Seidel, Jamie (26 October 2017). ["'Alien' object excites astronomers. Is it a 'visitor' from nearby star?"](http://www.nzherald.co.nz/technology/news/article.cfm?c_id=5&objectid=11937034). [The New Zealand Herald](https://en.wikipedia.org/wiki/The_New_Zealand_Herald "The New Zealand Herald"). [Archived](https://web.archive.org/web/20180924131335/https://www.nzherald.co.nz/technology/news/article.cfm?c_id=5&objectid=11937034) from the original on 24 September 2018. Retrieved 29 October 2017.
56. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Hein2017_59-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Hein2017_59-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Hein2017_59-2) Hein, A.M.; Perakis, N.; Long, K.F.; Crowl, A.; Eubanks, M.; Kennedy, R.G. III; Osborne, R. (2017). "Project Lyra: Sending a Spacecraft to 1I/ʻOumuamua (former A/2017 U1), the Interstellar Asteroid". [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1711.03155](https://arxiv.org/abs/1711.03155) [[physics.space-ph](https://arxiv.org/archive/physics.space-ph)].
57. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-precoveryobs_60-0) ["MPEC 2017-U185: A/2017 U1"](http://www.minorplanetcenter.net/mpec/K17/K17UI5.html). *Minor Planet Center*. International Astronomical Union. 26 October 2017. [Archived](https://web.archive.org/web/20171101170918/http://www.minorplanetcenter.net/mpec/K17/K17UI5.html) from the original on 1 November 2017. Retrieved 26 October 2017.
58. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-62) ["Inbound 2300 AU in 1606"](https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%271I%27&START_TIME=%271606-02-01%27&STOP_TIME=%271606-04-01%27&STEP_SIZE=%27120%27&QUANTITIES=%2719,22%27&CENTER=%27@Sun%27).
59. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-63) [Inbound 1 AU](https://ssd.jpl.nasa.gov/api/horizons.api?format=text&COMMAND=%271I%27&START_TIME=%272017-08-09%2012:00%27&STOP_TIME=%272017-08-09%2013:00%27&STEP_SIZE=%27120%27&QUANTITIES=%2719,22%27&CENTER=%27@Sun%27) (passing Earth's orbit)
60. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-65) ["Outbound 100 AU in 2034"](https://ssd.jpl.nasa.gov/api/horizons.api?format=text&COMMAND=%271I%27&START_TIME=%272034-01-01%27&STOP_TIME=%272034-12-31%27&STEP_SIZE=%27120%27&QUANTITIES=%2719,22%27&CENTER=%27@Sun%27).
61. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-66) [Outbound 2300 AU in 2429](https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%271I%27&START_TIME=%272429-02-01%27&STOP_TIME=%272429-04-01%27&STEP_SIZE=%27120%27&QUANTITIES=%2719,22%27&CENTER=%27@Sun%27)
62. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-67) Clark, Stuart (20 November 2017). ["Mysterious object confirmed to be from another solar system"](https://www.theguardian.com/science/across-the-universe/2017/nov/20/interstellar-object-confirmed-to-be-from-another-solar-system). *The Guardian*. [Archived](https://web.archive.org/web/20200425034932/https://www.theguardian.com/science/across-the-universe/2017/nov/20/interstellar-object-confirmed-to-be-from-another-solar-system) from the original on 25 April 2020. Retrieved 21 November 2017. "Astronomers are now certain that the mysterious object detected hurtling past our Sun last month is indeed from another solar system. They have named it 1I/2017 U1 (ʻOumuamua) and estimate it could be one of 10,000 others lurking undetected in our cosmic neighbourhood."
63. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-JPL-ecc_68-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-JPL-ecc_68-1) ["JPL Small-Body Database Search Engine – Constraints: e > 1"](https://ssd.jpl.nasa.gov/sbdb_query.cgi?obj_group=all;obj_kind=all;obj_numbered=all;OBJ_field=0;ORB_field=0;c1_group=ORB;c1_item=Bg;c1_op=%3E;c1_value=1;table_format=HTML;max_rows=50;format_option=comp;c_fields=AcBhBgBjBiCk;.cgifields=format_option;.cgifields=ast_orbit_class;.cgifields=table_format;.cgifields=obj_kind;.cgifields=obj_group;.cgifields=obj_numbered;.cgifields=com_orbit_class&query=1&c_sort=BgD). *[JPL Small-Body Database](https://en.wikipedia.org/wiki/JPL_Small-Body_Database "JPL Small-Body Database")*. [Jet Propulsion Laboratory](https://en.wikipedia.org/wiki/Jet_Propulsion_Laboratory "Jet Propulsion Laboratory"). [Archived](https://web.archive.org/web/20191209165519/http://ssd.jpl.nasa.gov/sbdb_query.cgi?obj_group=all;obj_kind=all;obj_numbered=all;OBJ_field=0;ORB_field=0;c1_group=ORB;c1_item=Bg;c1_op=%3E;c1_value=1;table_format=HTML;max_rows=50;format_option=comp;c_fields=AcBhBgBjBiCk;.cgifields=format_option;.cgifields=ast_orbit_class;.cgifields=table_format;.cgifields=obj_kind;.cgifields=obj_group;.cgifields=obj_numbered;.cgifields=com_orbit_class&query=1&c_sort=BgD) from the original on 9 December 2019. Retrieved 26 October 2017.
64. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-orientation_69-0) de la Fuente Marcos, C.; de la Fuente Marcos, R.úl (1 November 2017). ["Pole, Pericenter, and Nodes of the Interstellar Minor Body A/2017 U1"](https://doi.org/10.3847%2F2515-5172%2Faa96b4). *[Research Notes of the AAS](https://en.wikipedia.org/wiki/Research_Notes_of_the_AAS "Research Notes of the AAS")*. **1** (1): 5. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1711.00445](https://arxiv.org/abs/1711.00445). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2017RNAAS...1....5D](https://ui.adsabs.harvard.edu/abs/2017RNAAS...1....5D). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2515-5172/aa96b4](https://doi.org/10.3847%2F2515-5172%2Faa96b4). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [119537175](https://api.semanticscholar.org/CorpusID:119537175).
65. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Wright_71-0) Wright, Jason T.; Jones, Hugh R. A. (2018). ["On Distinguishing Interstellar Objects Like ʻOumuamua From Products of Solar System Scattering"](https://doi.org/10.3847%2F2515-5172%2Faa9f23). *Research Notes of the AAS*. **1** (1): 38. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1712.06044](https://arxiv.org/abs/1712.06044). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2017RNAAS...1...38W](https://ui.adsabs.harvard.edu/abs/2017RNAAS...1...38W). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2515-5172/aa9f23](https://doi.org/10.3847%2F2515-5172%2Faa9f23). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [119467366](https://api.semanticscholar.org/CorpusID:119467366).
66. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-hyperbolics_72-0) de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl; Aarseth, Sverre J. (2018). ["Where the Solar system meets the solar neighbourhood: patterns in the distribution of radiants of observed hyperbolic minor bodies"](https://doi.org/10.1093%2Fmnrasl%2Fsly019). *Monthly Notices of the Royal Astronomical Society Letters*. **476** (1): L1–L5. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1802.00778](https://arxiv.org/abs/1802.00778). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018MNRAS.476L...1D](https://ui.adsabs.harvard.edu/abs/2018MNRAS.476L...1D). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1093/mnrasl/sly019](https://doi.org/10.1093%2Fmnrasl%2Fsly019). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [119405023](https://api.semanticscholar.org/CorpusID:119405023).
67. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-74) ["Sedna inbound 200 AU in 1746"](https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%27Sedna%27&START_TIME=%271746-07-01%27&STOP_TIME=%271746-09-01%27&STEP_SIZE=%2730%27&QUANTITIES=%2719,22%27&CENTER=%27@Sun%27).
68. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-75) ["Bowell (C/1980 E1) inbound 200 AU in 1765"](https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%271980+E1%27&START_TIME=%271764-12-15%27&STOP_TIME=%271765-02-01%27&STEP_SIZE=%2730%27&QUANTITIES=%2719,22%27&CENTER=%27@Sun%27).
69. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-76) ["ISON inbound 200 AU in 1801"](https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%272012+S1%27&START_TIME=%271801-11-01%27&STOP_TIME=%271801-12-31%27&STEP_SIZE=%2760%27&QUANTITIES=%2719,22%27&CENTER=%27@Sun%27).
70. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-77) ["Inbound 200 AU in 1982"](https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%271I%27&START_TIME=%271982-10-10%27&STOP_TIME=%271982-11-05%27&STEP_SIZE=%2730%27&QUANTITIES=%2719,22%27&CENTER=%27@Sun%27).
71. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-78) ["2I/Borisov inbound 200 AU in 1991"](https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%272I%27&START_TIME=%271991-01-01%27&STOP_TIME=%271991-03-01%27&STEP_SIZE=%2730%27&QUANTITIES=%2719,22%27&CENTER=%27@Sun%27).
72. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NASA-FAQ_79-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NASA-FAQ_79-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NASA-FAQ_79-2) [4](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NASA-FAQ_79-3) ["Interstellar Asteroid FAQs"](https://www.nasa.gov/planetarydefense/faq/interstellar). [NASA](https://en.wikipedia.org/wiki/NASA "NASA"). 20 November 2017. [Archived](https://web.archive.org/web/20191218124241/https://www.nasa.gov/planetarydefense/faq/interstellar/) from the original on 18 December 2019. Retrieved 21 November 2017.
73. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-80) Battams, Karl (9 October 2013). ["Comet ISON is doing just fine!"](https://web.archive.org/web/20171028042815/http://www.isoncampaign.org/karl/ison-is-just-fine). *NASA Comet ISON Observing Campaign*. Archived from [the original](http://www.isoncampaign.org/karl/ison-is-just-fine) on 28 October 2017. Retrieved 12 December 2017.
74. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-UT-230181031_83-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-UT-230181031_83-1) Williams, Matt (2 November 2018). ["Could Oumuamua Be an Extra-Terrestrial Solar Sail?"](https://www.universetoday.com/140391/could-oumuamua-be-an-extra-terrestrial-solar-sail/). *[Universe Today](https://en.wikipedia.org/wiki/Universe_Today "Universe Today")*. [Archived](https://web.archive.org/web/20181103042615/https://www.universetoday.com/140391/could-oumuamua-be-an-extra-terrestrial-solar-sail/) from the original on 3 November 2018. Retrieved 2 November 2018.
75. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-ARX-20181101_84-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-ARX-20181101_84-1) Bialy, Shmuel; Loeb, Abraham (26 October 2018). ["Could Solar Radiation Explain ʻOumuamua's Peculiar Acceleration?"](https://doi.org/10.3847%2F2041-8213%2Faaeda8). *The Astrophysical Journal*. **868** (1): L1. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1810.11490](https://arxiv.org/abs/1810.11490). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018ApJ...868L...1B](https://ui.adsabs.harvard.edu/abs/2018ApJ...868L...1B). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2041-8213/aaeda8](https://doi.org/10.3847%2F2041-8213%2Faaeda8). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [118956077](https://api.semanticscholar.org/CorpusID:118956077).
76. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-ARX-20181108072_85-0) Trilling, David; al., et (20 November 2018). ["Spitzer Observations of Interstellar Object 1I/'Omumuamua"](https://doi.org/10.3847%2F1538-3881%2Faae88f). *The Astronomical Journal*. **156** (6): 261. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1811.08072](https://arxiv.org/abs/1811.08072). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018AJ....156..261T](https://ui.adsabs.harvard.edu/abs/2018AJ....156..261T). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/1538-3881/aae88f](https://doi.org/10.3847%2F1538-3881%2Faae88f). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [119444117](https://api.semanticscholar.org/CorpusID:119444117).
77. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NASA-20180627nasa_86-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NASA-20180627nasa_86-1) Cofield, Calla; Chou, Felicia; Wendel, JoAnna; Weaver, Donna; Villard, Ray (27 June 2018). ["Our Solar System's First Known Interstellar Object Gets Unexpected Speed Boost"](https://www.jpl.nasa.gov/news/news.php?feature=7173). *[NASA](https://en.wikipedia.org/wiki/NASA "NASA")*. [Archived](https://web.archive.org/web/20180627194643/https://www.jpl.nasa.gov/news/news.php?feature=7173) from the original on 27 June 2018. Retrieved 27 June 2018.
78. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Mamajek2017_87-0) Mamajek, Eric (2017). "Kinematics of the Interstellar Vagabond A/2017 U1". [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1710.11364](https://arxiv.org/abs/1710.11364) [[astro-ph.EP](https://arxiv.org/archive/astro-ph.EP)].
79. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Ye2017_88-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Ye2017_88-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Ye2017_88-2) Ye, Q.-Z.; Zhang, Q. (5 December 2017). ["1I/ʻOumuamua is Hot: Imaging, Spectroscopy and Search of Meteor Activity"](https://authors.library.caltech.edu/83727/1/Ye_2017_ApJL_851_L5.pdf) (PDF). *The Astrophysical Journal Letters*. **851** (1): L5. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1711.02320](https://arxiv.org/abs/1711.02320). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2017ApJ...851L...5Y](https://ui.adsabs.harvard.edu/abs/2017ApJ...851L...5Y). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2041-8213/aa9a34](https://doi.org/10.3847%2F2041-8213%2Faa9a34). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [119392232](https://api.semanticscholar.org/CorpusID:119392232). [Archived](https://web.archive.org/web/20180723033917/https://authors.library.caltech.edu/83727/1/Ye_2017_ApJL_851_L5.pdf) (PDF) from the original on 23 July 2018. Retrieved 3 November 2018.
80. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-89) Moór, A.; Szabó, Gy. M.; Kiss, L. L.; Kiss, Cs.; Ábrahám, P.; Szulágyi, J.; Kóspál, Á.; Szalai, T. (2013). ["Unveiling new members in five nearby young moving groups"](https://doi.org/10.1093%2Fmnras%2Fstt1381). *Monthly Notices of the Royal Astronomical Society*. **435** (2): 1376–1388. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1309.1669](https://arxiv.org/abs/1309.1669). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2013MNRAS.435.1376M](https://ui.adsabs.harvard.edu/abs/2013MNRAS.435.1376M). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1093/mnras/stt1381](https://doi.org/10.1093%2Fmnras%2Fstt1381). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [54584506](https://api.semanticscholar.org/CorpusID:54584506).
81. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Gaidos2017_90-0) Gaidos, E.; Williams, J.P.; Kraus, A. (2017). ["Origin of Interstellar Object A/2017 U1 in a Nearby Young Stellar Association?"](https://doi.org/10.3847%2F2515-5172%2Faa9851). *[Research Notes of the AAS](https://en.wikipedia.org/wiki/Research_Notes_of_the_AAS "Research Notes of the AAS")*. **1** (1): 13. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1711.01300](https://arxiv.org/abs/1711.01300). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2017RNAAS...1...13G](https://ui.adsabs.harvard.edu/abs/2017RNAAS...1...13G). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2515-5172/aa9851](https://doi.org/10.3847%2F2515-5172%2Faa9851). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [119091790](https://api.semanticscholar.org/CorpusID:119091790).
82. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-white_dwarf_91-0) Hansen, Brad; Zuckerman, Ben (December 2017). ["Ejection of Material—'Jurads'—from Post-main-sequence Planetary Systems"](https://doi.org/10.3847%2F2515-5172%2Faaa3ee). *Research Notes of the American Astronomical Society*. **1** (1). 55. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1712.07247](https://arxiv.org/abs/1712.07247). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2017RNAAS...1...55H](https://ui.adsabs.harvard.edu/abs/2017RNAAS...1...55H). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2515-5172/aaa3ee](https://doi.org/10.3847%2F2515-5172%2Faaa3ee). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [118957210](https://api.semanticscholar.org/CorpusID:118957210).
83. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-PortegiesZwartetal2017_92-0) Portegies Zwart, S.; Pelupessy, I.; Bedorf, J.; Cai, M.; Torres, S. (9 November 2017). ["The origin of interstellar asteroidal objects like 1I/2017 U1"](https://doi.org/10.1093%2Fmnrasl%2Fsly088). *Monthly Notices of the Royal Astronomical Society: Letters*. **479** (1): L17–L22. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1711.03558](https://arxiv.org/abs/1711.03558). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018MNRAS.479L..17P](https://ui.adsabs.harvard.edu/abs/2018MNRAS.479L..17P). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1093/mnrasl/sly088](https://doi.org/10.1093%2Fmnrasl%2Fsly088). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [56249057](https://api.semanticscholar.org/CorpusID:56249057).
84. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Bailer-Jones2018_94-0) Bailer-Jones, Coryn A. L.; et al. (18 October 2018). ["Plausible Home Stars of the Interstellar Object ʻOumuamua Found in Gaia DR2"](https://doi.org/10.3847%2F1538-3881%2Faae3eb). *[The Astronomical Journal](https://en.wikipedia.org/wiki/The_Astronomical_Journal "The Astronomical Journal")*. **156** (5): 205. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1809.09009](https://arxiv.org/abs/1809.09009). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018AJ....156..205B](https://ui.adsabs.harvard.edu/abs/2018AJ....156..205B). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/1538-3881/aae3eb](https://doi.org/10.3847%2F1538-3881%2Faae3eb). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [119051284](https://api.semanticscholar.org/CorpusID:119051284).
85. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-95) Bailer-Jones, C. A. L.; et al. ["Plausible home stars of the interstellar object ʻOumuamua found in Gaia DR2"](http://www.mpia.de/homes/calj/gdr2_oumuamua.html). *Coryn Bailer-Jones*. [Archived](https://web.archive.org/web/20181023120401/http://www.mpia.de/homes/calj/gdr2_oumuamua.html) from the original on 23 October 2018. Retrieved 23 October 2018.
86. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-ARX-20180924_96-0) Feng, Fabo; Jones, Hugh R. A. (2018). ["Plausible home stars of the interstellar object ʻOumuamua found in Gaia DR2"](https://doi.org/10.3847%2F1538-3881%2Faae3eb). *The Astronomical Journal*. **156** (5): 205. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1809.09009](https://arxiv.org/abs/1809.09009). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018AJ....156..205B](https://ui.adsabs.harvard.edu/abs/2018AJ....156..205B). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/1538-3881/aae3eb](https://doi.org/10.3847%2F1538-3881%2Faae3eb). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [119051284](https://api.semanticscholar.org/CorpusID:119051284).
87. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-97) Bartels, Meghan (25 September 2018). ["ʻOumuamua Isn't from Our Solar System. Now We May Know Which Star It Came From"](https://www.space.com/41928-where-did-oumuamua-come-from.html). *Space.com*. [Archived](https://web.archive.org/web/20180925210517/https://www.space.com/41928-where-did-oumuamua-come-from.html) from the original on 25 September 2018. Retrieved 25 September 2018.
88. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-EA-20200413_98-0) [University of California, Santa Cruz](https://en.wikipedia.org/wiki/University_of_California,_Santa_Cruz "University of California, Santa Cruz") (13 April 2020). ["New formation theory explains the mysterious interstellar object ʻOumuamua – A new scenario based on computer simulations accounts for all of the observed characteristics of the first known interstellar object to visit our solar system"](https://www.eurekalert.org/pub_releases/2020-04/uoc--nft041020.php). *[EurekAlert!](https://en.wikipedia.org/wiki/EurekAlert! "EurekAlert!")*. [Archived](https://web.archive.org/web/20200414124012/https://www.eurekalert.org/pub_releases/2020-04/uoc--nft041020.php) from the original on 14 April 2020. Retrieved 13 April 2020.
89. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NA-20200413_99-0) Zhang, Yun; Lin, Douglas N. C. (13 April 2020). ["Tidal fragmentation as the origin of 1I/2017 U1 (ʻOumuamua)"](https://www.nature.com/articles/s41550-020-1065-8). *[Nature Astronomy](https://en.wikipedia.org/wiki/Nature_Astronomy "Nature Astronomy")*. **254** (9): 852–860. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[2004.07218](https://arxiv.org/abs/2004.07218). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2020NatAs...4..852Z](https://ui.adsabs.harvard.edu/abs/2020NatAs...4..852Z). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1038/s41550-020-1065-8](https://doi.org/10.1038%2Fs41550-020-1065-8). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [215768701](https://api.semanticscholar.org/CorpusID:215768701). [Archived](https://web.archive.org/web/20200414123834/https://www.nature.com/articles/s41550-020-1065-8) from the original on 14 April 2020. Retrieved 13 April 2020.
90. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-100) Ćuk, Matija (2018). ["1I/ʻOumuamua as a Tidal Disruption Fragment From a Binary Star System"](https://doi.org/10.3847%2F2041-8213%2Faaa3db). *[The Astrophysical Journal](https://en.wikipedia.org/wiki/The_Astrophysical_Journal "The Astrophysical Journal")*. **852** (1): L15. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1712.01823](https://arxiv.org/abs/1712.01823). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018ApJ...852L..15C](https://ui.adsabs.harvard.edu/abs/2018ApJ...852L..15C). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2041-8213/aaa3db](https://doi.org/10.3847%2F2041-8213%2Faaa3db). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [54959652](https://api.semanticscholar.org/CorpusID:54959652).
91. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Seligman2020-05_102-0) Seligman, D.; Laughlin, G. (2020). ["Evidence that 1I/2017 U1 (ʻOumuamua) was composed of molecular hydrogen ice"](https://doi.org/10.3847%2F2041-8213%2Fab963f). *The Astrophysical Journal*. **896** (1): L8. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[2005.12932](https://arxiv.org/abs/2005.12932). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2020ApJ...896L...8S](https://ui.adsabs.harvard.edu/abs/2020ApJ...896L...8S). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2041-8213/ab963f](https://doi.org/10.3847%2F2041-8213%2Fab963f). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [218900854](https://api.semanticscholar.org/CorpusID:218900854).
92. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Hoang2020-06_103-0) Hoang, T.; [Loeb, Abraham](https://en.wikipedia.org/wiki/Avi_Loeb "Avi Loeb") (2020). ["Destruction of molecular hydrogen ice and Implications for 1I/2017 U1 (ʻOumuamua)"](https://doi.org/10.3847%2F2041-8213%2Fabab0c). *The Astrophysical Journal*. **899** (2): L23. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[2006.08088](https://arxiv.org/abs/2006.08088). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2020ApJ...899L..23H](https://ui.adsabs.harvard.edu/abs/2020ApJ...899L..23H). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2041-8213/abab0c](https://doi.org/10.3847%2F2041-8213%2Fabab0c). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [219687520](https://api.semanticscholar.org/CorpusID:219687520).
93. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NAT-20180627_105-0) Witze, Alexandra (27 June 2018). ["Mysterious interstellar visitor is a comet – not an asteroid – Quirks in ʻOumuamua's path through the Solar System helped researchers solve a case of mistaken identity"](https://www.nature.com/articles/d41586-018-05552-9). *[Nature](https://en.wikipedia.org/wiki/Nature_(journal) "Nature (journal)")*. [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1038/d41586-018-05552-9](https://doi.org/10.1038%2Fd41586-018-05552-9). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [126317359](https://api.semanticscholar.org/CorpusID:126317359). [Archived](https://web.archive.org/web/20180627181835/https://www.nature.com/articles/d41586-018-05552-9) from the original on 27 June 2018. Retrieved 27 June 2018.
94. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-eso1820June2018Oumuamua_106-0) ["ESO's VLT Sees ʻOumuamua Getting a Boost – New results indicate interstellar nomad ʻOumuamua is a comet"](http://www.eso.org/public/news/eso1820/). *www.eso.org*. 27 June 2018. [Archived](https://web.archive.org/web/20180703210038/http://eso.org/public/news/eso1820/) from the original on 3 July 2018. Retrieved 28 June 2018. "Such outgassing is a behaviour typical for comets and contradicts the previous classification of ʻOumuamua as an interstellar asteroid. "We think this is a tiny, weird comet," commented [Marco Micheli](https://en.wikipedia.org/wiki/Marco_Micheli "Marco Micheli"). "We can see in the data that its boost is getting smaller the farther away it travels from the Sun, which is typical for comets.""
95. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-darkComet_107-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-darkComet_107-1) Seligman, Darryl Z.; Meech, Karen J.; et al. (9 December 2024). ["Two distinct populations of dark comets delineated by orbits and sizes"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11665882). *Proceedings of the National Academy of Sciences of the United States of America*. **1** (51) e2406424121. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[2412.07603](https://arxiv.org/abs/2412.07603). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2024PNAS..12106424S](https://ui.adsabs.harvard.edu/abs/2024PNAS..12106424S). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1073/pnas.2406424121](https://doi.org/10.1073%2Fpnas.2406424121). [PMC](https://en.wikipedia.org/wiki/PMC_(identifier) "PMC (identifier)") [11665882](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11665882). [PMID](https://en.wikipedia.org/wiki/PMID_(identifier) "PMID (identifier)") [39652762](https://pubmed.ncbi.nlm.nih.gov/39652762).
96. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-WHT_108-0) Fitzsimmons, Alan [@FitzsimmonsAlan] (27 October 2017). ["Spectrum of A/2017 U1 obtained on Wednesday night with the @INGLaPalma 4.2m WHT. Colour is red like Kuiper Belt Objects, featureless"](https://twitter.com/FitzsimmonsAlan/status/923928561722982400) ([Tweet](https://en.wikipedia.org/wiki/Tweet_(social_media) "Tweet (social media)")) – via [Twitter](https://en.wikipedia.org/wiki/Twitter "Twitter").
97. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Fitzsimmons2017a_109-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Fitzsimmons2017a_109-1) [3](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Fitzsimmons2017a_109-2) [4](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Fitzsimmons2017a_109-3) Fitzsimmons, A.; et al. (18 December 2017). ["Spectroscopy and thermal modelling of the first interstellar object 1I/2017 U1 ʻOumuamua"](https://pure.qub.ac.uk/portal/en/publications/spectroscopy-and-thermal-modelling-of-the-first-interstellar-object-1i2017-u1-oumuamua(433758b2-c945-4038-8c19-b4e5b52ae1e2).html). *Nature Astronomy*. **2** (2): 133. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1712.06552](https://arxiv.org/abs/1712.06552). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018NatAs...2..133F](https://ui.adsabs.harvard.edu/abs/2018NatAs...2..133F). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1038/s41550-017-0361-4](https://doi.org/10.1038%2Fs41550-017-0361-4). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [216937304](https://api.semanticscholar.org/CorpusID:216937304). [Archived](https://web.archive.org/web/20191017090156/https://pure.qub.ac.uk/portal/en/publications/spectroscopy-and-thermal-modelling-of-the-first-interstellar-object-1i2017-u1-oumuamua(433758b2-c945-4038-8c19-b4e5b52ae1e2).html) from the original on 17 October 2019. Retrieved 25 September 2018. "The discovery epoch photometry implies a highly elongated body with radii of ~200×20 m when a comet-like geometric albedo of 0.04 is assumed. Here we report spectroscopic characterisation of ʻOumuamua, finding it to be variable with time but similar to organically rich surfaces found in the outer Solar System. The observable ISO population is expected to be dominated by comet-like bodies in agreement with our spectra, yet the reported inactivity implies a lack of surface ice. We show this is consistent with predictions of an insulating mantle produced by long-term cosmic ray exposure. An internal icy composition cannot therefore be ruled out by the lack of activity, even though ʻOumuamua passed within 0.25 au of the Sun."
98. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-110) Drahus, M.; Guzik, P.; Waniak, W.; Handzlik, B.; Kurowski, S.; Xu, S. (1 December 2017). "Tumbling motion of 1I/ʻOumuamua reveals body's violent past". [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1712.00437](https://arxiv.org/abs/1712.00437) [[astro-ph.EP](https://arxiv.org/archive/astro-ph.EP)].
99. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-ESO2017_111-0) Meech, Karen; et al. (20 November 2017). ["Light curve of interstellar asteroid ʻOumuamua"](https://www.eso.org/public/images/eso1737f/). *ESO*. European Southern Observatory. [Archived](https://web.archive.org/web/20191219152200/https://www.eso.org/public/images/eso1737f/) from the original on 19 December 2019. Retrieved 21 November 2017.
100. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-113) Amos, Jonathan (11 February 2018). ["ʻOumuamua: 'space cigar's' tumble hints at violent past"](https://www.bbc.com/news/science-environment-43018706). *BBC News*. [Archived](https://web.archive.org/web/20180724044444/https://www.bbc.com/news/science-environment-43018706) from the original on 24 July 2018. Retrieved 21 July 2018.
101. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-114) Belton, M. J. S.; et al. (10 April 2018). ["The Excited Spin State of 1I/2017 U1 ʻOumuamua"](https://doi.org/10.3847%2F2041-8213%2Faab370). *The Astrophysical Journal*. **856** (2): L21. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1804.03471](https://arxiv.org/abs/1804.03471). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2018ApJ...856L..21B](https://ui.adsabs.harvard.edu/abs/2018ApJ...856L..21B). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2041-8213/aab370](https://doi.org/10.3847%2F2041-8213%2Faab370). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [119336678](https://api.semanticscholar.org/CorpusID:119336678). "We find that ʻOumuamua is 'cigar-shaped', if close to its lowest rotational energy, and an extremely oblate spheroid if close to its highest energy state for its total angular momentum."
102. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-115) Thomas, C. A.; Trilling, D. E.; Emery, J. P.; Mueller, M.; Hora, J. L.; Benner, L. A. M.; Bhattacharya, B.; Bottke, W. F.; Chesley, S. (1 September 2011). ["ExploreNEOs. V. Average Albedo by Taxonomic Complex in the Near-Earth Asteroid Population"](https://doi.org/10.1088%2F0004-6256%2F142%2F3%2F85). *The Astronomical Journal*. **142** (3): 85. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2011AJ....142...85T](https://ui.adsabs.harvard.edu/abs/2011AJ....142...85T). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1088/0004-6256/142/3/85](https://doi.org/10.1088%2F0004-6256%2F142%2F3%2F85). [ISSN](https://en.wikipedia.org/wiki/ISSN_(identifier) "ISSN (identifier)") [0004-6256](https://search.worldcat.org/issn/0004-6256).
103. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Guarddian2017-12-11_116-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Guarddian2017-12-11_116-1) Ian Sample (11 December 2017). ["Astronomers to check interstellar body for signs of alien technology"](https://www.theguardian.com/science/2017/dec/11/astronomers-to-check-interstellar-body-for-signs-of-alien-technology). *The Guardian*. [Archived](https://web.archive.org/web/20200425025003/https://www.theguardian.com/science/2017/dec/11/astronomers-to-check-interstellar-body-for-signs-of-alien-technology) from the original on 25 April 2020. Retrieved 12 December 2017. "Green Bank telescope in West Virginia will listen for radio signals from ʻOumuamua, an object from another solar system ... "Most likely it is of natural origin, but because it is so peculiar, we would like to check if it has any sign of artificial origin, such as radio emissions," said Avi Loeb, professor of astronomy at Harvard University and an adviser to the Breakthrough Listen project. "If we do detect a signal that appears artificial in origin, we'll know immediately." ... While many astronomers believe the object is an interstellar asteroid, its elongated shape is unlike anything seen in the asteroid belt in our own solar system. Early observations of ʻOumuamua show that it is about 400m long but only one tenth as wide. "It's curious that the first object we see from outside the solar system looks like that," said Loeb."
104. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-Mashchenko2019_117-0) Mashchenko, Sergey (November 2019). ["Modeling the light curve of ʻOumuamua: evidence for torque and disc-like shape"](https://doi.org/10.1093%2Fmnras%2Fstz2380). *Monthly Notices of the Royal Astronomical Society*. **489** (3): 3003–3021. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1906.03696](https://arxiv.org/abs/1906.03696). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2019MNRAS.489.3003M](https://ui.adsabs.harvard.edu/abs/2019MNRAS.489.3003M). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1093/mnras/stz2380](https://doi.org/10.1093%2Fmnras%2Fstz2380). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [182952355](https://api.semanticscholar.org/CorpusID:182952355).
105. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-rotationpole_118-0) de la Fuente Marcos, C.; de la Fuente Marcos, R. (1 November 2020). ["Constraining the orientation of the spin axes of extrasolar minor bodies 1I/2017 U1 (ʻOumuamua) and 2I/Borisov"](https://www.aanda.org/articles/aa/abs/2020/11/aa37447-20/aa37447-20.html). *[Astronomy and Astrophysics](https://en.wikipedia.org/wiki/Astronomy_and_Astrophysics "Astronomy and Astrophysics")*. **643**: A18 (17 pp). [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[2009.08423](https://arxiv.org/abs/2009.08423). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2020A&A...643A..18D](https://ui.adsabs.harvard.edu/abs/2020A&A...643A..18D). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1051/0004-6361/202037447](https://doi.org/10.1051%2F0004-6361%2F202037447). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [221761422](https://api.semanticscholar.org/CorpusID:221761422). [Archived](https://web.archive.org/web/20210201045557/https://www.aanda.org/articles/aa/abs/2020/11/aa37447-20/aa37447-20.html) from the original on 1 February 2021. Retrieved 27 October 2020.
106. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-119) Voosen, Paul (20 November 2017). ["Updated: For the first time, astronomers are tracking a distant visitor streaking through our solar system"](https://www.science.org/content/article/updated-first-time-astronomers-are-tracking-distant-visitor-streaking-through-our-solar). *Science*. [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.1126/science.aar3433](https://doi.org/10.1126%2Fscience.aar3433). [Archived](https://web.archive.org/web/20171121122550/http://www.sciencemag.org/news/2017/11/updated-first-time-astronomers-are-tracking-distant-visitor-streaking-through-our-solar) from the original on 21 November 2017. Retrieved 30 November 2017.
107. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-120) O'Neill, Ian (20 November 2017). ["Wow! 1st Interstellar Asteroid Is a Spinning Space Cigar"](https://www.space.com/38838-interstellar-asteroid-oumuamua-space-cigar.html). *Space.com*. [Archived](https://web.archive.org/web/20200425005615/https://www.space.com/38838-interstellar-asteroid-oumuamua-space-cigar.html) from the original on 25 April 2020. Retrieved 30 November 2017.
108. [1](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-MattWilliams2017-11-20a_121-0) [2](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-MattWilliams2017-11-20a_121-1) Williams, Matt (20 November 2017). ["That Interstellar Asteroid is probably pretty strange looking"](https://www.universetoday.com/137944/interstellar-asteroid-probably-pretty-strange-looking/). [Universe Today](https://en.wikipedia.org/wiki/Universe_Today "Universe Today"). [Archived](https://web.archive.org/web/20171222052002/https://www.universetoday.com/137944/interstellar-asteroid-probably-pretty-strange-looking/) from the original on 22 December 2017. Retrieved 20 December 2017. "Its dark and reddened surface is also an indication of tholins, which are the result of organic molecules (like methane) being irradiated by cosmic rays for millions of years."
109. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-MattWilliams2017-11-24a_122-0) Williams, Matt (24 November 2017). ["Project Lyra, a mission to chase down that interstellar asteroid"](https://www.universetoday.com/137960/project-lyra-mission-chase-interstellar-asteroid-1/). [Universe Today](https://en.wikipedia.org/wiki/Universe_Today "Universe Today"). [Archived](https://web.archive.org/web/20171230124909/https://www.universetoday.com/137960/project-lyra-mission-chase-interstellar-asteroid-1/) from the original on 30 December 2017. Retrieved 20 December 2017. "It was also determined to be rocky and metal rich, and to contain traces of tholins – organic molecules that have been irradiated by UV radiation." Also here  [Archived](https://web.archive.org/web/20171222052951/https://phys.org/news/2017-11-lyra-mission-interstellar-asteroid.html) 22 December 2017 at the [Wayback Machine](https://en.wikipedia.org/wiki/Wayback_Machine "Wayback Machine") at Phys.org
110. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-ES-20191126_123-0) Anderson, Paul Scott (26 November 2019). ["Was ʻOumuamua a cosmic dust bunny?"](https://earthsky.org/space/was-oumuamua-a-cosmic-dust-bunny). *[Earth & Sky](https://en.wikipedia.org/wiki/Earth_&_Sky "Earth & Sky")*. [Archived](https://web.archive.org/web/20191127204418/https://earthsky.org/space/was-oumuamua-a-cosmic-dust-bunny) from the original on 27 November 2019. Retrieved 27 November 2019.
111. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-TAJL-20191111_124-0) Flekkøy, Eirik G.; et al. (11 November 2019). ["The Interstellar Object ʻOumuamua as a Fractal Dust Aggregate"](https://hal-insu.archives-ouvertes.fr/insu-02366685/file/2019-FlekkoyLuuToussaint-Flekk%C3%B8y_2019_ApJL_885_L41.pdf) (PDF). *[The Astrophysical Journal Letters](https://en.wikipedia.org/wiki/The_Astrophysical_Journal_Letters "The Astrophysical Journal Letters")*. **885** (2): L41. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[1910.07135](https://arxiv.org/abs/1910.07135). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2019ApJ...885L..41F](https://ui.adsabs.harvard.edu/abs/2019ApJ...885L..41F). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2041-8213/ab4f78](https://doi.org/10.3847%2F2041-8213%2Fab4f78). [S2CID](https://en.wikipedia.org/wiki/S2CID_(identifier) "S2CID (identifier)") [204734116](https://api.semanticscholar.org/CorpusID:204734116). [Archived](https://web.archive.org/web/20210201045530/https://hal-insu.archives-ouvertes.fr/insu-02366685/file/2019-FlekkoyLuuToussaint-Flekk%C3%B8y_2019_ApJL_885_L41.pdf) (PDF) from the original on 1 February 2021. Retrieved 30 November 2019.
112. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-UT-20200908_125-0) Tomaswick, Andy (8 September 2020). ["Okay, New Idea. Oumuamua is an Interstellar 'Dust Bunny'"](https://www.universetoday.com/147675/okay-new-idea-oumuamua-is-an-interstellar-dust-bunny/). *[Universe Today](https://en.wikipedia.org/wiki/Universe_Today "Universe Today")*. [Archived](https://web.archive.org/web/20200911021825/https://www.universetoday.com/147675/okay-new-idea-oumuamua-is-an-interstellar-dust-bunny/) from the original on 11 September 2020. Retrieved 9 September 2020.
113. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-PHY-20200817_126-0) [Harvard-Smithsonian Center for Astrophysics](https://en.wikipedia.org/wiki/Harvard-Smithsonian_Center_for_Astrophysics "Harvard-Smithsonian Center for Astrophysics") and [Korea Astronomy and Space Science Institute](https://en.wikipedia.org/wiki/Korea_Astronomy_and_Space_Science_Institute "Korea Astronomy and Space Science Institute") (17 August 2020). ["Scientists determine ʻOumuamua isn't made from molecular hydrogen ice after all"](https://phys.org/news/2020-08-scientists-oumuamua-isnt-molecular-hydrogen.html). *[Phys.org](https://en.wikipedia.org/wiki/Phys.org "Phys.org")*. [Archived](https://web.archive.org/web/20200817190804/https://phys.org/news/2020-08-scientists-oumuamua-isnt-molecular-hydrogen.html) from the original on 17 August 2020. Retrieved 17 August 2020.
114. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-AJL-20200817_127-0) Hoang, Thiem; [Loeb, Abraham](https://en.wikipedia.org/wiki/Avi_Loeb "Avi Loeb") (17 August 2020). ["Destruction of Molecular Hydrogen Ice and Implications for 1I/2017 U1 (ʻOumuamua)"](https://doi.org/10.3847%2F2041-8213%2Fabab0c). *[The Astrophysical Journal Letters](https://en.wikipedia.org/wiki/The_Astrophysical_Journal_Letters "The Astrophysical Journal Letters")*. **899** (2): L23. [arXiv](https://en.wikipedia.org/wiki/ArXiv_(identifier) "ArXiv (identifier)"):[2006.08088](https://arxiv.org/abs/2006.08088). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2020ApJ...899L..23H](https://ui.adsabs.harvard.edu/abs/2020ApJ...899L..23H). [doi](https://en.wikipedia.org/wiki/Doi_(identifier) "Doi (identifier)"):[10.3847/2041-8213/abab0c](https://doi.org/10.3847%2F2041-8213%2Fabab0c).
115. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-128) ["Breakthrough Listen Releases Initial Results and Data from Observations of ʻOumuamua"](http://breakthroughinitiatives.org/news/15). Breakthrough Listen. 13 December 2017. [Archived](https://web.archive.org/web/20171215053410/http://breakthroughinitiatives.org/news/15) from the original on 15 December 2017. Retrieved 15 December 2017. "No evidence of artificial signals emanating from the object so far detected by the Green Bank Telescope, but monitoring and analysis continue. Initial data are available for public inspection in the Breakthrough Listen archive"
116. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-129) Ian Sample (15 December 2017). ["Is ʻOumuamua an alien spacecraft? Initial scans show no signs of technology"](https://www.theguardian.com/science/2017/dec/14/is-oumuamua-an-alien-spacecraft-first-scans-show-no-signs-of-technology). *The Guardian*. [Archived](https://web.archive.org/web/20171215000127/https://www.theguardian.com/science/2017/dec/14/is-oumuamua-an-alien-spacecraft-first-scans-show-no-signs-of-technology) from the original on 15 December 2017. Retrieved 15 December 2017.
117. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-130) Siegel, Ethan (10 February 2021). ["New Theory Perfectly Explains ʻOumuamua Naturally: It's A Nitrogen Iceberg"](https://www.forbes.com/sites/startswithabang/2021/02/10/new-theory-perfectly-explains-oumuamua-naturally-from-exo-pluto-collisions/). *[Forbes](https://en.wikipedia.org/wiki/Forbes "Forbes")*. [Archived](https://web.archive.org/web/20210213203138/https://www.forbes.com/sites/startswithabang/2021/02/10/new-theory-perfectly-explains-oumuamua-naturally-from-exo-pluto-collisions/) from the original on 13 February 2021. Retrieved 13 February 2021.
118. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-PHYS-20210317_131-0) Staff (17 March 2021). ["Scientists determine the origin of extra-solar object ʻOumuamua"](https://phys.org/news/2021-03-scientists-extra-solar-oumuamua.html). *[Phys.org](https://en.wikipedia.org/wiki/Phys.org "Phys.org")*. Retrieved 17 March 2021.
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154. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NASA-20220408_167-0) Handal, Josh; Fox, Karen; Talbert, Tricia (8 April 2022). ["U.S. Space Force Releases Decades of Bolide Data to NASA for Planetary Defense Studies"](https://www.nasa.gov/feature/us-space-force-releases-decades-of-bolide-data-to-nasa-for-planetary-defense-studies). *[NASA](https://en.wikipedia.org/wiki/NASA "NASA")*. Retrieved 11 April 2022.
155. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-TDB-20220923_168-0) Loeb, Avi (23 September 2022). ["The discovery of a second interstellar meteor"](https://thedebrief.org/the-discovery-of-a-second-interstellar-meteor/). *TheDebrief.org*. Retrieved 24 September 2022.
156. [↑](https://en.wikipedia.org/wiki/1I/ʻOumuamua#cite_ref-NYT-20240311_169-0) Richtel, Matt (11 March 2024). ["Surprise: An 'Extraterrestrial' Gadget Was Something More Familiar - In 2014 a fireball from outer space was posited to be an alien artifact. A recent study suggests otherwise"](https://www.nytimes.com/2024/03/11/science/meteor-avi-loeb.html). *[The New York Times](https://en.wikipedia.org/wiki/The_New_York_Times "The New York Times")*. Retrieved 11 March 2024.`{{cite news}}`: CS1 maint: deprecated archival service ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_deprecated_archival_service "Category:CS1 maint: deprecated archival service"))

## External links

[![Wikimedia Commons logo](https://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/40px-Commons-logo.svg.png)](https://en.wikipedia.org/wiki/File:Commons-logo.svg)

Wikimedia Commons has media related to [1I/ʻOumuamua](https://commons.wikimedia.org/wiki/Category:1I/ʻOumuamua "commons:Category:1I/ʻOumuamua").

* ["ʻOumuamua: The first known interstellar object to visit our solar system"](https://solarsystem.nasa.gov/small-bodies/asteroids/oumuamua/in-depth/). NASA.gov. 29 November 2017.
* Where is ʻOumuamua in the sky: [The Sky Live](https://theskylive.com/oumuamua-info)
* Talk about [A/2017 U1](https://www.facebook.com/SETIInstitute/videos/10155677978165535/) from 31 October 2017. [SETI Institute](https://en.wikipedia.org/wiki/SETI_Institute "SETI Institute") at [Facebook Live](https://en.wikipedia.org/wiki/Facebook_Live "Facebook Live").
* [Interstellar Asteroid A/2017 U1 *(update 7 November 2017)*](https://www.youtube.com/watch?v=k7y65DyrsbY) on [YouTube](https://en.wikipedia.org/wiki/YouTube_video_(identifier) "YouTube video (identifier)") (time 3:31 min.)
* ["Spitzer DDT observations of the interstellar comet A/2017 U1"](http://ssc.spitzer.caltech.edu/warmmission/scheduling/approvedprograms/ddt/13249.txt). Caltech.edu. Proposal #13249
* ["Planet 1I/2017 U1"](https://web.archive.org/web/20171108035255/http://exoplanet.eu/catalog/1i/2017_u1/). *[Extrasolar Planets Encyclopaedia](https://en.wikipedia.org/wiki/Extrasolar_Planets_Encyclopaedia "Extrasolar Planets Encyclopaedia")*. Archived from [the original](http://exoplanet.eu/catalog/1i/2017_u1/) on 8 November 2017. Retrieved 8 November 2017.
* [1I/ʻOumuamua](https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=3788040) at the *[JPL Small-Body Database](https://en.wikipedia.org/wiki/JPL_Small-Body_Database "JPL Small-Body Database")* [![Edit this at Wikidata](https://upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/20px-OOjs_UI_icon_edit-ltr-progressive.svg.png)](https://www.wikidata.org/wiki/Q42313338#P716 "Edit this at Wikidata")
  + [Close approach](https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=3788040&view=C) **·** [Discovery](https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=3788040&view=D) **·** [Ephemeris](https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=3788040) **·** [Orbit viewer](https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=3788040&view=V) **·** [Orbit parameters](https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=3788040&view=O) **·** [Physical parameters](https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=3788040&view=P)
* ["A piece of an extrasolar Pluto may have passed through our cosmic neighborhood, a new study suggests."](https://www.nytimes.com/2021/03/23/science/astronomy-oumuamua-comet.html), article by [Dennis Overbye](https://en.wikipedia.org/wiki/Dennis_Overbye "Dennis Overbye"), New York Times, Updated March 29, 2021
* ["A Glimpse of ʻOumuamua"](https://www.nytimes.com/video/science/100000005592208/glimpse-of-oumuamua.html). *[The New York Times](https://en.wikipedia.org/wiki/The_New_York_Times "The New York Times")* (Video – 2:53). Narrated by Dennis Overbye; Produced by Jonathan Corum and Jason Drakeford. 12 December 2017.`{{cite news}}`: CS1 maint: others ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_others "Category:CS1 maint: others"))
* [Science fiction story about ʻOumuamua by astronomer Andrew Fraknoi](https://wyldblood.com/the-listener-between-worlds/)
* [Interactive 3D gravity simulation of ʻOumuamua's Solar System flyby](https://gravitysimulator.org/solar-system/oumuamua) [Archived](https://web.archive.org/web/20200903042335/https://gravitysimulator.org/solar-system/oumuamua/) 3 September 2020 at the [Wayback Machine](https://en.wikipedia.org/wiki/Wayback_Machine "Wayback Machine")

| * [v](https://en.wikipedia.org/wiki/Template:2017_in_space "Template:2017 in space") * [t](https://en.wikipedia.org/wiki/Template_talk:2017_in_space "Template talk:2017 in space") * [e](https://en.wikipedia.org/wiki/Special:EditPage/Template:2017_in_space "Special:EditPage/Template:2017 in space")  2017 in space | | |
| --- | --- | --- |
| * « [2016](https://en.wikipedia.org/wiki/Template:2016_in_space "Template:2016 in space")  [2018](https://en.wikipedia.org/wiki/Template:2018_in_space "Template:2018 in space") » | | |
| [Space probe launches](https://en.wikipedia.org/wiki/2017_in_spaceflight "2017 in spaceflight") [Space probes launched in 2017](https://en.wikipedia.org/wiki/Category:Space_probes_launched_in_2017 "Category:Space probes launched in 2017") | * [ASTERIA](https://en.wikipedia.org/wiki/ASTERIA_(spacecraft) "ASTERIA (spacecraft)") (miniature space telescope; August 2017) |  |
| [Impact events](https://en.wikipedia.org/wiki/Impact_event "Impact event") | * [Bolides in 2017](https://en.wikipedia.org/wiki/List_of_bolides_in_2017 "List of bolides in 2017") * [2017 China bolide](https://en.wikipedia.org/wiki/2017_China_bolide "2017 China bolide") |
| Selected [NEOs](https://en.wikipedia.org/wiki/Near-Earth_object "Near-Earth object") | * [Asteroid close approaches](https://en.wikipedia.org/wiki/List_of_asteroid_close_approaches_to_Earth_in_2017 "List of asteroid close approaches to Earth in 2017") * [2017 AG13](https://en.wikipedia.org/wiki/2017_AG13 "2017 AG13") * [2017 BS5](https://en.wikipedia.org/wiki/2017_BS5 "2017 BS5") * [2017 BQ6](https://en.wikipedia.org/wiki/2017_BQ6 "2017 BQ6") * [2016 WF9](https://en.wikipedia.org/wiki/2016_WF9 "2016 WF9") * [(671294) 2014 JO25](https://en.wikipedia.org/wiki/(671294)_2014_JO25 "(671294) 2014 JO25") * [2017 OO1](https://en.wikipedia.org/wiki/2017_OO1 "2017 OO1") * [2017 QP1](https://en.wikipedia.org/wiki/2017_QP1 "2017 QP1") * [3122 Florence](https://en.wikipedia.org/wiki/3122_Florence "3122 Florence") * [2017 SX17](https://en.wikipedia.org/wiki/2017_SX17 "2017 SX17") * [2012 TC4](https://en.wikipedia.org/wiki/2012_TC4 "2012 TC4") * [2017 TD6](https://en.wikipedia.org/wiki/2017_TD6 "2017 TD6") * [2017 VL2](https://en.wikipedia.org/wiki/2017_VL2 "2017 VL2") * [2017 VW13](https://en.wikipedia.org/wiki/2017_VW13 "2017 VW13") * [2017 XO2](https://en.wikipedia.org/wiki/2017_XO2 "2017 XO2") * [3200 Phaethon](https://en.wikipedia.org/wiki/3200_Phaethon "3200 Phaethon") |
| [Exoplanets](https://en.wikipedia.org/wiki/List_of_exoplanets_discovered_in_2017 "List of exoplanets discovered in 2017") [Exoplanets discovered in 2017](https://en.wikipedia.org/wiki/Category:Exoplanets_discovered_in_2017 "Category:Exoplanets discovered in 2017") | * [HATS-36b](https://en.wikipedia.org/wiki/HATS-36b "HATS-36b") * [HD 113996 b](https://en.wikipedia.org/wiki/HD_113996_b "HD 113996 b") * [KELT-18b](https://en.wikipedia.org/wiki/KELT-18b "KELT-18b") * [Kepler-19d](https://en.wikipedia.org/wiki/Kepler-19d "Kepler-19d") * [Kepler-80g](https://en.wikipedia.org/wiki/Kepler-80 "Kepler-80") * [Kepler-90i](https://en.wikipedia.org/wiki/Kepler-90i "Kepler-90i") * [K2-66b](https://en.wikipedia.org/wiki/K2-66b "K2-66b") * [K2-138b](https://en.wikipedia.org/wiki/K2-138b "K2-138b") * [LHS 1140 b](https://en.wikipedia.org/wiki/LHS_1140_b "LHS 1140 b") * [Luyten b](https://en.wikipedia.org/wiki/Luyten_b "Luyten b") * [NGTS-1b](https://en.wikipedia.org/wiki/NGTS-1b "NGTS-1b") * [OGLE-2016-BLG-1190Lb](https://en.wikipedia.org/wiki/OGLE-2016-BLG-1190Lb "OGLE-2016-BLG-1190Lb") * [OGLE-2016-BLG-1195Lb](https://en.wikipedia.org/wiki/OGLE-2016-BLG-1195Lb "OGLE-2016-BLG-1195Lb") * [Ross 128 b](https://en.wikipedia.org/wiki/Ross_128_b "Ross 128 b") * [Tau Ceti](https://en.wikipedia.org/wiki/Tau_Ceti#Planetary_system "Tau Ceti")   + [g](https://en.wikipedia.org/wiki/Tau_Ceti_g "Tau Ceti g")   + [h](https://en.wikipedia.org/wiki/Tau_Ceti_h "Tau Ceti h") * [TRAPPIST-1](https://en.wikipedia.org/wiki/TRAPPIST-1 "TRAPPIST-1")   + [e](https://en.wikipedia.org/wiki/TRAPPIST-1e "TRAPPIST-1e")   + [f](https://en.wikipedia.org/wiki/TRAPPIST-1f "TRAPPIST-1f")   + [g](https://en.wikipedia.org/wiki/TRAPPIST-1g "TRAPPIST-1g")   + [h](https://en.wikipedia.org/wiki/TRAPPIST-1h "TRAPPIST-1h") * dark [albedo](https://en.wikipedia.org/wiki/Albedo "Albedo") of [WASP-12b](https://en.wikipedia.org/wiki/WASP-12b "WASP-12b") * [WASP-107b](https://en.wikipedia.org/wiki/WASP-107b "WASP-107b") * [YZ Ceti](https://en.wikipedia.org/wiki/YZ_Ceti "YZ Ceti")   + b   + c   + d |
| Discoveries | * [GW170104](https://en.wikipedia.org/wiki/GW170104 "GW170104") * [Ring of Haumea](https://en.wikipedia.org/wiki/Haumea#Ring "Haumea") * 2 [moons of Jupiter](https://en.wikipedia.org/wiki/Moons_of_Jupiter "Moons of Jupiter") * [GW170608](https://en.wikipedia.org/wiki/GW170608 "GW170608") * [Saraswati Supercluster](https://en.wikipedia.org/wiki/Saraswati_Supercluster "Saraswati Supercluster") * [GW170814](https://en.wikipedia.org/wiki/GW170814 "GW170814") * [IGR J17329-2731](https://en.wikipedia.org/wiki/IGR_J17329-2731 "IGR J17329-2731") (X-ray source) * [GW170817](https://en.wikipedia.org/wiki/GW170817 "GW170817") [neutron star merger](https://en.wikipedia.org/wiki/Neutron_star_merger "Neutron star merger") * [1I/ʻOumuamua](https://en.wikipedia.org/wiki/1I/ʻOumuamua) * [ULAS J1342+0928](https://en.wikipedia.org/wiki/ULAS_J1342+0928 "ULAS J1342+0928") * [RZ Piscium](https://en.wikipedia.org/wiki/RZ_Piscium "RZ Piscium") |
| Comets [Comets in 2017](https://en.wikipedia.org/wiki/Category:Comets_in_2017 "Category:Comets in 2017") | * [C/2016 U1 (NEOWISE)](https://en.wikipedia.org/wiki/C/2016_U1_(NEOWISE) "C/2016 U1 (NEOWISE)") * [41P/Tuttle–Giacobini–Kresák](https://en.wikipedia.org/wiki/41P/Tuttle–Giacobini–Kresák "41P/Tuttle–Giacobini–Kresák") * [103P/Hartley](https://en.wikipedia.org/wiki/103P/Hartley "103P/Hartley") * [C/2015 ER61 (PanSTARRS)](https://en.wikipedia.org/wiki/C/2015_ER61_(PanSTARRS) "C/2015 ER61 (PanSTARRS)") * [C/2015 V2 (Johnson)](https://en.wikipedia.org/wiki/C/2015_V2_(Johnson) "C/2015 V2 (Johnson)") * [P/2006 VW139](https://en.wikipedia.org/wiki/(300163)_2006_VW139 "(300163) 2006 VW139") * [C/2017 O1 (ASASSN)](https://en.wikipedia.org/wiki/C/2017_O1_(ASASSN) "C/2017 O1 (ASASSN)") * [96P/Machholz](https://en.wikipedia.org/wiki/96P/Machholz "96P/Machholz") |
| Space exploration | * [*Cassini* retirement](https://en.wikipedia.org/wiki/Cassini_retirement "Cassini retirement") (impacted into Saturn; Sep 2017) * [OSIRIS-REx](https://en.wikipedia.org/wiki/OSIRIS-REx "OSIRIS-REx") (Earth gravity assist; Sep 2017) |
| * [Outer space portal](https://en.wikipedia.org/wiki/Portal:Outer_space "Portal:Outer space") * [Category:2016 in outer space](https://en.wikipedia.org/wiki/Category:2016_in_outer_space "Category:2016 in outer space") — **[Category:2017 in outer space](https://en.wikipedia.org/wiki/Category:2017_in_outer_space "Category:2017 in outer space")** — [Category:2018 in outer space](https://en.wikipedia.org/wiki/Category:2018_in_outer_space "Category:2018 in outer space") | | |

[Portals](https://en.wikipedia.org/wiki/Wikipedia:Contents/Portals "Wikipedia:Contents/Portals"):

* ![](https://upload.wikimedia.org/wikipedia/commons/thumb/0/00/Crab_Nebula.jpg/20px-Crab_Nebula.jpg) [Astronomy](https://en.wikipedia.org/wiki/Portal:Astronomy "Portal:Astronomy")
* [![icon](https://upload.wikimedia.org/wikipedia/commons/thumb/5/5f/He1523a.jpg/20px-He1523a.jpg)](https://en.wikipedia.org/wiki/File:He1523a.jpg) [Stars](https://en.wikipedia.org/wiki/Portal:Stars "Portal:Stars")
* ![](https://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/RocketSunIcon.svg/20px-RocketSunIcon.svg.png) [Spaceflight](https://en.wikipedia.org/wiki/Portal:Spaceflight "Portal:Spaceflight")
* ![](https://upload.wikimedia.org/wikipedia/commons/thumb/8/83/Solar_system.jpg/20px-Solar_system.jpg) [Solar System](https://en.wikipedia.org/wiki/Portal:Solar_System "Portal:Solar System")

| [Authority control databases](https://en.wikipedia.org/wiki/Help:Authority_control "Help:Authority control") [Edit this at Wikidata](https://www.wikidata.org/wiki/Q42313338#identifiers "Edit this at Wikidata") | |
| --- | --- |
| National | * [Czech Republic](https://aleph.nkp.cz/F/?func=find-c&local_base=aut&ccl_term=ica=ph1118282&CON_LNG=ENG) |
| Other | * [JPL SBDB](https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=3788040) * [MPC](https://www.minorplanetcenter.net/db_search/show_object?object_id=1I) |