1I/ʻOumuamua

Interstellar object that passed near Earth in 2017 March 2023 yes 1I/Oumuamua #FFE0C2 A2017U1 5gsmoothWHT enhanced.jpg 1.25 Oumuamua on 28 October 20175-minute exposure taken by the William Herschel Telescope on 28 October; Oumuamua appears as a light source in the center of the image, while background stars appear streaked due to the speed of Oumuamua as the telescope tracked it.Bonnell Jerry Nemiroff Robert Robert J. Nemiroff A/2017 U1: An Interstellar Visitor https://apod.nasa.gov/apod/ap171103.html Astronomy Picture of the Day 13 March 2019 https://web.archive.org/web/20190313070147/https://apod.nasa.gov/apod/ap171103.html 13 March 2019 3 November 2017 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. live Robert Weryk using Pan-STARRS 1 Haleakalā Obs., Hawaii 19 October 2017 1I/2017 U1 1I 1I/Oumuamua 1I/2017 U1 (Oumuamua) A/2017 U1 C/2017 U1 P10Ee5V oʊ ˌ m uː ə ˈ m uː ə, haw ʔowˈmuwəˈmuwə lang Haw-oumuamua.oga Hawaiian term for scout Interstellar object Hyperbolic asteroid 23 November 2017 (JD 2458080.5) 80 days 0.255916 0.000007 none AU 9 September 2017 (87.71 km/s) −1.2723 0.0001 none AUObjects on hyperbolic trajectories have negative semimajor axis, giving them a positive orbital energy. 1.20113 0.00002 none 122.74° 24.597° 241.811° 51.158° 0.6867 ms / day 0.0958 AU 37.3 LD 1.454 AU 26.33 0.01 km/s (interstellar) 5.55 AU/year 115 x 111 x 19 m Mashchenko S. 182952355 Modeling the light curve of Oumuamua: evidence for torque and disc-like shape Monthly Notices of the Royal Astronomical Society 2019 489 3 3003–3021 10.1093/mnras/stz2380 free 1906.03696 2019MNRAS.489.3003M 100 - 1000 m longCofield Calia NASA Learns More About Interstellar Visitor Oumuamua https://www.jpl.nasa.gov/news/news.php?feature=7280 14 November 2018 NASA 14 November 2018 15 April 2020 https://web.archive.org/web/20200415092634/https://www.jpl.nasa.gov/news/news.php?feature=7280 live Watzke Megan Spitzer Observations of Interstellar Object Oumuamua https://scitechdaily.com/spitzer-observations-of-interstellar-object-oumuamua/ 20 October 2018 SciTechDaily.com 20 October 2018 16 October 2019 https://web.archive.org/web/20191016101409/https://scitechdaily.com/spitzer-observations-of-interstellar-object-oumuamua/ live https://www.cfa.harvard.edu/news/su201842 Oumuamua Smithsonian Astrophysical Observatory 19 October 2018 24 October 2019 1 February 2021 https://web.archive.org/web/20210201045549/https://www.cfa.harvard.edu/news/su201842 live 230 x 35 x 35 m(est. at albedo 0.10) Tumbling (non-principal axis rotation)Reported values include:8.10 0.02 h 8.10 0.42 h 6.96 1.45 -0.39 hOumuamua as a messenger from the Local Association The Astrophysical Journal F. Feng H. R. A. Jones 56197486 amp 852 2 L27 23 November 2017 1711.08800 10.3847/2041-8213/aaa404 2018ApJ...852L..27F free 0.1 (spectral est.) 0.06–0.08 (spectral est.) B–V 0.7 0.06 V-R 0.45 0.05 g-r 0.47 0.04 r-i 0.36 0.16 r-J 1.20 0.11 22.08 0.45 19.7 to >27.5Range 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 for fast-moving objects) around 1 January 2018. By late 2019, it should have dimmed to 34 mag. 1I/Oumuamua is the first confirmed interstellar object detected passing through the Solar System.Osborne Hannah 2019-04-16 First meteor of interstellar origin discovered by scientists https://www.newsweek.com/first-interstellar-meteor-discovered-1397886 2022-04-11 Newsweek en Formally designated 1I/2017 U1, it was discovered by Canadian physicist Robert Weryk using the Pan-STARRS telescope at Haleakalā Observatory, Hawaii, on 19 October 2017, approximately 40 days after it passed its closest point to the Sun on 9 September. When it was first observed, it was about 33 million km (21 million mi; 0.22 AU) from Earth (about 85 times as far away as the Moon) and already heading away from the Sun. Oumuamua is a small object estimated to be between 100 and 1000 m ft 1 long, with its width and thickness both estimated between 35 and 167 m ft. It has a red color, like objects in the outer Solar System. Despite its close approach to the Sun, it showed no signs of having a coma, the usual nebula around comets formed when they pass near the Sun. Further, it exhibited nongravitational acceleration, potentially due to outgassing or a push from solar radiation pressure.Carlisle Camille M. 12 March 2019 Oumuamua sped up as it left the inner solar system. This may be why – Astronomers think a jet-powered rocking motion could solve the puzzle Salon https://www.salon.com/2019/03/12/oumuamua-sped-up-as-it-left-the-inner-solar-system-this-might-be-why_partner/ 12 March 2019 19 March 2020 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/ live 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, assuming little systematic error, presents its motion as "tumbling" rather than "spinning", and moving sufficiently fast relative to the Sun that it is likely of extrasolar origin. 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. Its planetary system of origin and age are unknown. Oumuamua is remarkable for its extrasolar origin, high obliqueness, 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 Oumuamua to be of a density similar to rocky asteroids,McNeill Andrew Trilling David E. Mommert Michael 56163074 1 April 2018 Constraints on the Density and Internal Strength of 1I/Oumuamua 2018ApJ...857L...1M The Astrophysical Journal Letters 857 1 L1 10.3847/2041-8213/aab9ab 0004-637X 1803.09864 free a small amount of internal strength similar to icy cometsShi X. Vincent J-B. Tubiana C. Toth I. Pajola M. Oklay N. Naletto G. Mottola S. Marzari F. 44120504 1 March 2018 Tensile strength of 67P/Churyumov–Gerasimenko nucleus material from overhangs Astronomy & Astrophysics en 611 A33 10.1051/0004-6361/201732155 free 0004-6361 2018A&A...611A..33A 1712.07508 would allow it to have a relatively low density. Proposed explanations of its origin include the remnant of a disintegrated rogue comet, or a piece of an exoplanet rich in nitrogen ice, similar to Pluto.Jackson Alan P. et al 1I/Oumuamua as an N2 ice fragment of an exo-Pluto surface: I. Size and Compositional Constraints 16 March 2021 Journal of Geophysical Research: Planets 126 5 e2020JE006706 10.1029/2020JE006706 2103.08788 2021JGRE..12606706J free Desch S. J. et al. 1I/Oumuamua as an N2 ice fragment of an exo-Pluto surface II: Generation of N2 ice fragments and the origin of Oumuamua 16 March 2021 Journal of Geophysical Research: Planets 126 5 e2020JE006807 10.1029/2020JE006807 2103.08812 2021JGRE..12606807D free Overbye Dennis Dennis Overbye 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 23 March 2021 The New York Times 23 March 2021 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",Bergner Jennifer Seligman Darryl Z. Acceleration of 1I/Oumuamua from radiolytically produced H2 in H2O ice https://www.nature.com/articles/s41586-022-05687-w 22 March 2023 Nature 615 7953 610–613 10.1038/s41586-022-05687-w 36949336 2303.13698 257668585 23 March 2023 consistent with Oumuamua being an interstellar comet, "originating as a planetesimal relic broadly similar to solar system comets".Overbye Dennis Dennis Overbye 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 22 March 2023 The New York Times 23 March 2023 Name thumb|Hyperbolic trajectory of Oumuamua, during 2017, through the inner Solar System with the Sun at the focushttps://photojournal.jpl.nasa.gov/archive/PIA22357_JPL-20180620-ASTRDSf-0007-Interstellar%20Asteroid%20animation-720p.mp4 animation NASA 29 September 2025 As the first known object of its type, Oumuamua presented a unique case for the 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 was created: I, for Interstellar object. As the first object so identified, Oumuamua 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/Oumuamua; or 1I/2017 U1 (Oumuamua). The name comes haw oumuamua scout (ou reach out for mua, reduplicated for emphasis first, in advance of), 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'.https://www.outerplaces.com/science/item/17035-interstellar-object-asteroid-oumuamua Our Solar System's First Interstellar Asteroid is Named Oumuamua' Kesh Johnathan 8 November 2017 Outer Places 23 November 2017 1 December 2017 https://web.archive.org/web/20171201032243/https://www.outerplaces.com/science/item/17035-interstellar-object-asteroid-oumuamua live The first character (not a diacritic) is a Hawaiian okina, not an apostrophe, and is pronounced as a glottal stop; the Pan-STARRS team chose the nameWall Mike 16 November 2017 Meet Oumuamua, the First-Ever Asteroid from Another Star http://www.scientificamerican.com/article/meet-oumuamua-the-first-ever-asteroid-from-another-star Scientific American en Space.com 24 November 2017 22 November 2017 https://web.archive.org/web/20171122224917/https://www.scientificamerican.com/article/meet-oumuamua-the-first-ever-asteroid-from-another-star/ live in consultation with Kaiu Kimura and Larry Kimura of the University of Hawaii at Hilo.http://www.hawaii.edu/news/2017/11/20/an-interstellar-visitor-unmasked An interstellar visitor unmasked Gal Roy 20 November 2017 University of Hawaii System News 22 November 2017 en-US 24 November 2017 https://web.archive.org/web/20171124124145/http://www.hawaii.edu/news/2017/11/20/an-interstellar-visitor-unmasked/ live 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 by Arthur C. Clarke.https://www.economist.com/news/science-and-technology/21730863-rendezvous-rama-first-visitor-another-solar-system-has-just-been The first visitor from another solar system has just been spotted: Rendezvous with Rama? The Economist 2 November 2017 subscription 6 December 2017 6 December 2017 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 live Observations Observations and conclusions concerning Oumuamua's trajectory were primarily obtained with data from the Pan-STARRS1 Telescope, part of the Spaceguard Survey,Morrison David David Morrison (astrophysicist) Interstellar Visitor: The Strange Asteroid from a Faraway System Skeptical Inquirer March–April 2018 42 2 9 and the Canada–France–Hawaii Telescope (CFHT), and its composition and shape from the Very Large Telescope and the Gemini South telescope in Chile,Gemini Observatory http://www.gemini.edu/node/12729 First Known Interstellar Visitor is an 'Oddball' 20 November 2017 28 November 2017 23 November 2017 https://web.archive.org/web/20171123071154/http://www.gemini.edu/node/12729 live and the Keck II telescope in Hawaii. These were collected by Karen J. Meech, Robert Weryk, and their colleagues and published in Nature on 20 November 2017.https://www.bbc.com/news/science-environment-42053634 Bizarre shape of interstellar asteroid BBC News Paul Rincon 20 November 2017 20 November 2017 8 April 2020 https://web.archive.org/web/20200408062702/https://www.bbc.com/news/science-environment-42053634 live After the announcement, the space-based telescopes Hubble and Spitzer joined in the observations. thumb|Oumuamua had faded to 34th magnitude by 2020. Oumuamua is small and not very luminous. It was not seen in STEREO HI-1A observations near its perihelion on 9 September 2017, limiting its brightness to approximately 13.5 mag. By the end of October, it had already faded to about apparent magnitude 23, and in mid-December 2017, it was too faint and fast-moving to be studied by even the largest ground-based telescopes. Oumuamua was compared to the fictional alien spacecraft Rama due to its interstellar origin. Adding to the coincidence, both the real and the fictional objects are unusually elongated. Oumuamua has a reddish hue and unsteady brightness, which are typical of asteroids.John Wenz Astronomy http://www.astronomy.com/news/2017/11/interstellar-asteroid-is-a-quarter-mile-long-red-beast The first discovered interstellar asteroid is a quarter-mile long red beast 22 November 2017 6 December 2017 4 June 2019 https://web.archive.org/web/20190604023605/http://www.astronomy.com/news/2017/11/interstellar-asteroid-is-a-quarter-mile-long-red-beast live Overbye Dennis Dennis Overbye An Interstellar Visitor Both Familiar and Alien 22 November 2017 The New York Times https://www.nytimes.com/2017/11/22/science/oumuamua-space-asteroid.html 23 November 2017 17 April 2020 https://web.archive.org/web/20200417202638/https://www.nytimes.com/2017/11/22/science/oumuamua-space-asteroid.html live Seth Shostak Is this mysterious space rock actually an alien spaceship? https://www.nbcnews.com/mach/science/mysterious-space-rock-actually-alien-spaceship-ncna829501 NBC News 14 December 2017 20 December 2017 19 December 2017 https://web.archive.org/web/20171219145459/https://www.nbcnews.com/mach/science/mysterious-space-rock-actually-alien-spaceship-ncna829501 live The SETI Institute's radio telescope, the Allen Telescope Array, examined Oumuamua, but detected no unusual radio emissions. More detailed observations, using the Breakthrough Listen hardware and the Green Bank Telescope, were performed;https://www.wired.co.uk/article/oumuamua-is-not-an-interstellar-spacecraft It isn't an alien spacecraft, but we should still study Oumuamua Beall Abigail 12 December 2017 Wired UK 12 December 2017 12 December 2017 https://web.archive.org/web/20171212163216/http://www.wired.co.uk/article/oumuamua-is-not-an-interstellar-spacecraft live 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 of 0.08 watts.1801.02814 Breakthrough Listen Observations of 1I/Oumuamua with the GBT Research Notes of the American Astronomical Society 2 1 9 Enriquez J. E. 9 January 2018 2018RNAAS...2....9E 10.3847/2515-5172/aaa6c9 119435272 free Trajectory thumb|Seen from Earth, the apparent trajectory makes annual retrograde loops in the sky, with its origin in Lyra, temporarily moving south of the ecliptic between 2 September and 22 October 2017, and moving northward again towards its destination in Pegasus.thumb|Oumuamua's hyperbolic trajectory over the Solar System Oumuamua appears to have come from roughly the direction of Vega in the constellation Lyra.Jamie Seidel '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 26 October 2017 29 October 2017 24 September 2018 https://web.archive.org/web/20180924131335/https://www.nzherald.co.nz/technology/news/article.cfm?c_id=5&objectid=11937034 live Its inbound direction of motion is 6° from the 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. On 26 October, two precovery observations from the Catalina Sky Survey were found dated 14 and 17 October. A two-week observation arc had verified a strongly hyperbolic trajectory. It has a hyperbolic excess velocity (velocity at infinity, ) of 26.33 km/s kph mph on, its speed relative to the Sun when in interstellar space.For comparison, comet C/1980 E1 will only be moving 4.2 km/s when it is 500 AU from the Sun. + Oumuamua speed relative to the Sun Distance Date Velocity(km/s) 2300 AU 1606 26.41https://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 Inbound 2300 AU in 1606 1000 AU 1839 26.42 100 AU 2000 26.73 10 AU 2016 29.56 1 AU 9 August 2017 49.70Inbound 1 AU (passing Earth's orbit) Perihelion 9 September 2017 87.71 1 AU 10 October 2017 49.70The solar escape velocity from Earth's orbit (1 AU from the Sun) is 42.1 km/s.May 2026May 2026 For comparison, even 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 only moves at 29 km/s when 1 AU from the Sun because of the much smaller semi-major axis. 10 AU 2019 29.58 100 AU 2034 26.73https://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 Outbound 100 AU in 2034 1000 AU 2195 26.44 2300 AU 2429 26.40Outbound 2300 AU in 2429 By mid-November, astronomers were certain that it was an interstellar object.https://www.theguardian.com/science/across-the-universe/2017/nov/20/interstellar-object-confirmed-to-be-from-another-solar-system Mysterious object confirmed to be from another solar system 20 November 2017 21 November 2017 Stuart Clark The Guardian 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 (Oumuamua) and estimate it could be one of 10,000 others lurking undetected in our cosmic neighbourhood. en-GB 25 April 2020 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 live Based on observations spanning 80 days, Oumuamua's orbital eccentricity is 1.20, the highest ever observed until 2I/Borisov was discovered in August 2019. An eccentricity exceeding 1.0 means an object exceeds the Sun's 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,Unlike Oumuamua, C/1980 E1's orbit got its high eccentricity of 1.057 due to a close encounter with Jupiter. Its inbound-orbit eccentricity was less than 1. Oumuamua'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 Oumuamua's trajectory or boost its speed to the observed value. For these reasons, it can only be of interstellar origin.On Distinguishing Interstellar Objects Like Oumuamua From Products of Solar System Scattering 2018 Research Notes of the AAS 1 1 38 10.3847/2515-5172/aa9f23 2017RNAAS...1...38W 1712.06044 Wright Jason T. Jones Hugh R. A. 119467366 free de la Fuente Marcos Carlos de la Fuente Marcos Raúl Aarseth Sverre J. 119405023 2018 Where the Solar system meets the solar neighbourhood: patterns in the distribution of radiants of observed hyperbolic minor bodies Monthly Notices of the Royal Astronomical Society Letters 476 1 L1–L5 1802.00778 2018MNRAS.476L...1D 10.1093/mnrasl/sly019 free left|thumb|Animation of Oumuamua passing through the Solar System + Inbound velocity at 200 AU from the Suncompared to Oort cloud objects Object Velocity(km/s) # of observations and obs arcOrbits computed with only a handful of observations can be unreliable. Short arcs can result in computer generated orbits rejecting some data unnecessarily. 90377 Sedna 2.66https://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 Sedna inbound 200 AU in 1746 577 in 12512 days C/2010 X1 (Elenin) 2.96 2222 in 235 days C/1980 E1 (Bowell) 2.98https://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 Bowell (C/1980 E1) inbound 200 AU in 1765 187 in 2514 days C/1997 P2 (Spacewatch) 2.99 94 in 49 days C/2012 S1 (ISON) 2.99https://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 ISON inbound 200 AU in 1801 6514 in 784 days 1I/2017 U1 (Oumuamua) 26.55https://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 Inbound 200 AU in 1982 207 in 80 days 2I/Borisov 32.43https://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 2I/Borisov inbound 200 AU in 1991 3249 in 657 days Oumuamua entered the Solar System from north of the plane of the ecliptic. The pull of the Sun's gravity caused it to speed up until it reached its maximum speed of 87.71 km/s kph 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 km mi on from the Sun, i.e., about 17% closer than Mercury's closest approach to the Sun.Comet C/2012 S1 (ISON) peaked at 377 km/s kph at perihelionhttp://www.isoncampaign.org/karl/ison-is-just-fine Karl Battams NASA Comet ISON Observing Campaign Comet ISON is doing just fine! 9 October 2013 12 December 2017 28 October 2017 https://web.archive.org/web/20171028042815/http://www.isoncampaign.org/karl/ison-is-just-fine because it passed 0.0124 AU from the Sun (20 times closer than Oumuamua). It is now heading away from the Sun toward Pegasus, toward a vanishing point 66° from the direction of its approach.According to the formula: On the outward leg of its journey through the Solar System, Oumuamua passed beyond the orbit of Earth on 14 October with a closest approach distance of approximately 0.16175 AU km mi from Earth. On 16 October it moved back north of the ecliptic plane and passed beyond the orbit of Mars on 1 November. It passed beyond Jupiter's orbit in May 2018, beyond Saturn's orbit in January 2019, and beyond Neptune's in 2022. As it leaves the Solar System it will be approximately right ascension 23'51" and declination +24°42', in Pegasus. It will continue to slow down, approaching a speed of 26.33 km/s km/h mph relative to the Sun, the same speed it had before its approach to the Solar System. Non-gravitational acceleration On 27 June 2018, astronomers reported a non-gravitational acceleration to Oumuamua's trajectory, potentially consistent with a push from solar radiation pressure. 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, whereby volatile substances inside the object evaporate as the Sun heats its surface. Although no such tail of gasses was observed following the object,Trilling David al. et 119444117 Spitzer Observations of Interstellar Object 1I/'Omumuamua The Astronomical Journal 156 6 261 20 November 2018 1811.08072 10.3847/1538-3881/aae88f 2018AJ....156..261T free researchers estimated that enough outgassing may have increased the object's speed without the gases being detectable. A critical reassessment of the outgassing hypothesis argued that, instead of the observed stability of Oumuamua's spin, outgassing would have caused its spin to rapidly change due to its elongated shape, resulting in the object tearing apart. Indications of origin Accounting for Vega's proper motion, it would have taken Oumuamua 600,000 years to reach the Solar System from Vega, although it was not in the same part of the sky at that time. Astronomers calculate that 100 years ago the object was 561 ± 0.6 AU e9km e9mi each unit flip from the Sun and traveling at 26.33 km/s with respect to the Sun. 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 (LSR), and especially close to the mean motion of a relatively close group of red dwarf stars. This velocity profile also indicates an extrasolar origin, but appears to rule out the closest dozen stars. In fact, the closeness of Oumuamua'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. It is unknown how long the object has been traveling among the stars. The Solar System is likely the first planetary system Oumuamua has closely encountered since being ejected from its birth star system, potentially several billion years ago. It has been speculated that the object may have been ejected from a stellar system in one of the local kinematic associations of young stars (specifically, Carina or Columba) within a range of about 100 parsecs,2013 Unveiling new members in five nearby young moving groups Monthly Notices of the Royal Astronomical Society 435 2 1376–1388 10.1093/mnras/stt1381 1309.1669 Moór A. Szabó Gy. M. Kiss L. L. Kiss Cs. Ábrahám P. Szulágyi J. Kóspál Á. Szalai T. free 54584506 2013MNRAS.435.1376M 45 million years ago. The Carina and Columba associations are now very far in the sky from the Lyra constellation, the direction from which Oumuamua 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.Ejection of Material—'Jurads'—from Post-main-sequence Planetary Systems Research Notes of the American Astronomical Society Brad Hansen Ben Zuckerman 1 1 55 December 2017 10.3847/2515-5172/aaa3ee 2017RNAAS...1...55H 1712.07247 118957210 free About 1.3 million years ago the object may have passed within a distance of 0.16 pc off on to the nearby star 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 at a relative speed of about 15 km/s mph kph.This is true for the nominal position of the star. However, its actual distance is not known precisely: According to Gaia Data Release 1, the distance to TYC4742-1027-1 is 137 ± 13 pc off on. It is not known if an encounter actually occurred. Update: This star has new measurements in 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 Oumuamua. An August 2018 study using Gaia Data Release 2 updated the possible past close encounters and identified four stars—HIP 3757, HD 292249, Gaia DR2 2502921019565490176, and Gaia DR2 3666992950762141312—which Oumuamua passed relatively close to at moderately low velocities in the past few million years.Bailer-Jones Coryn A. L. etal 18 October 2018 Plausible Home Stars of the Interstellar Object Oumuamua Found in Gaia DR2 The Astronomical Journal 156 5 205 1809.09009 2018AJ....156..205B 10.3847/1538-3881/aae3eb Bailer-Jones2018 119051284 free This study also identifies future close encounters of Oumuamua on its outgoing trajectory from the Sun.Bailer-Jones C. A. L. etal Plausible home stars of the interstellar object Oumuamua found in Gaia DR2 http://www.mpia.de/homes/calj/gdr2_oumuamua.html Coryn Bailer-Jones 23 October 2018 23 October 2018 https://web.archive.org/web/20181023120401/http://www.mpia.de/homes/calj/gdr2_oumuamua.html live In September 2018, astronomers described several possible home star systems from which Oumuamua may have originated.Feng Fabo Jones Hugh R. A. 2018 Plausible home stars of the interstellar object Oumuamua found in Gaia DR2 The Astronomical Journal 156 5 205 1809.09009 2018AJ....156..205B 10.3847/1538-3881/aae3eb 119051284 free Bartels Meghan 25 September 2018 Oumuamua 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 live https://web.archive.org/web/20180925210517/https://www.space.com/41928-where-did-oumuamua-come-from.html 25 September 2018 25 September 2018 Space.com In April 2020, astronomers presented a new possible scenario for the object's origin.University of California, Santa Cruz New formation theory explains the mysterious interstellar object Oumuamua – 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 13 April 2020 EurekAlert! 13 April 2020 14 April 2020 https://web.archive.org/web/20200414124012/https://www.eurekalert.org/pub_releases/2020-04/uoc--nft041020.php live Zhang Yun Lin Douglas N. C. 215768701 Tidal fragmentation as the origin of 1I/2017 U1 (Oumuamua) https://www.nature.com/articles/s41550-020-1065-8 13 April 2020 Nature Astronomy 254 9 852–860 10.1038/s41550-020-1065-8 2004.07218 2020NatAs...4..852Z 13 April 2020 14 April 2020 https://web.archive.org/web/20200414123834/https://www.nature.com/articles/s41550-020-1065-8 live According to one hypothesis, Oumuamua could be a fragment from a tidally disrupted planet.Ćuk Matija 2018 1I/Oumuamua as a Tidal Disruption Fragment From a Binary Star System The Astrophysical Journal 852 1 L15 1712.01823 2018ApJ...852L..15C 10.3847/2041-8213/aaa3db 54959652 free See also 1801.02658 Ravikov Roman R. 1I/2017 Oumuamua-like Interstellar Asteroids as Possible Messengers from Dead Stars The Astrophysical Journal 2018 861 1 35 10.3847/1538-4357/aac5ef 2018ApJ...861...35R free . Oumuamua 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. If true, this would make Oumuamua 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 Oumuamua's lightcurve favors a disc-like shape. In May 2020, it was proposed that the object was the first observed member of a class of small H2-ice-rich bodies that form at temperatures near 3 K in the cores of giant molecular clouds. The non-gravitational acceleration and high aspect ratio shape of Oumuamua might be explainable on this basis. Seligman D. Laughlin G. 218900854 Evidence that 1I/2017 U1 (Oumuamua) was composed of molecular hydrogen ice The Astrophysical Journal 2020 896 1 L8 10.3847/2041-8213/ab963f 2005.12932 2020ApJ...896L...8S free However, it was later calculated that hydrogen icebergs cannot survive their journey through interstellar space. Hoang T. Loeb Abraham Avi Loeb Destruction of molecular hydrogen ice and Implications for 1I/2017 U1 (Oumuamua) The Astrophysical Journal 2020 899 2 L23 10.3847/2041-8213/abab0c 2006.08088 2020ApJ...899L..23H 219687520 free Classification Initially, Oumuamua was announced as comet C/2017 U1 (PANSTARRS) based on a strongly hyperbolic trajectory. In an attempt to confirm any cometary activity, very deep stacked images were taken at the Very Large Telescope later the same day, but the object showed no presence of a coma.According to 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. Accordingly, the object was renamed A/2017 U1, becoming the first comet ever to be re-designated as an asteroid. Once it was identified as an interstellar object, it was designated 1I/2017 U1, the first member of a new class of objects. The lack of a coma limits the amount of surface ice to a few square meters, and any volatiles (if they exist) must lie below a crust at least 0.5 m ft thick. It also indicates that the object must have formed within the frost line 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, as may be the case with damocloids.Not mentioned in previous cited source January 2018 It is difficult to say which scenario is more likely due to the chaotic nature of small body dynamics,Not mentioned in previous cited source January 2018 although if it formed in a similar manner to Solar System objects, its spectrum indicates that the latter scenario is true. Any meteoric activity from Oumuamua would have been expected to occur on 18 October 2017 coming from the constellation Sextans, but no activity was detected by the Canadian Meteor Orbit Radar. On 27 June 2018, astronomers reported that Oumuamua was thought to be a mildly active comet, and not an asteroid, as previously thought. This was determined by measuring a non-gravitational boost to Oumuamua's acceleration, consistent with comet outgassing. However, studies submitted in October 2018 suggest that the object is neither an asteroid nor a comet,Rafikov Roman R. Spin Evolution and Cometary Interpretation of the Interstellar Minor Object 1I/2017 Oumuamua 20 September 2018 1809.06389v2 astro-ph.EPSkibba Ramin 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/ 10 October 2018 Quanta Magazine 10 October 2018 27 April 2020 https://web.archive.org/web/20200427010524/https://www.quantamagazine.org/interstellar-comet-oumuamua-might-not-actually-be-a-comet-20181010/ live although the object could be a remnant of a disintegrated interstellar comet (or exocomet), as suggested by astronomer Zdenek Sekanina.Williams Matt 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 1 February 2019 Universe Today 2 February 2019 3 February 2019 https://web.archive.org/web/20190203030346/https://www.universetoday.com/141398/oumuamua-could-be-the-debris-cloud-of-a-disintegrated-interstellar-comet/#more-141398 live Sekanina Zdenek 1I/Oumuamua As Debris Of Dwarf Interstellar Comet That Disintegrated Before Perihelion 31 January 2019 1901.08704 astro-ph.EP But by 2024, astronomers had identified 14 asteroids with the same unusual behavior. 1 Two distinct populations of dark comets delineated by orbits and sizes 10.1073/pnas.2406424121 free 2024-12-09 Proceedings of the National Academy of Sciences of the United States of America 2 11665882 Darryl Z. Seligman Karen J. Meech Davide Farnocchia Marco Micheli Olivier R. Hainaut Henry H. Hsieh Adina D. Feinstein Steven R. Chesley Aster G. Taylor Joseph Masiero 51 e2406424121 39652762 2412.07603 2024PNAS..12106424S This makes ʻOumuamua the first member of another new class of objects called dark comets. Appearance, shape and composition Spectra from the Hale Telescope on 25 October showed red color resembling comet nuclei or Trojans. Higher signal to noise spectra recorded by the 4.2 m William Herschel Telescope later that day showed that the object was featureless, and colored red like Kuiper belt objects. Spectra obtained with the 8.2 m Very Large Telescope the following night showed that behavior continued into near-infrared wavelengths. Its spectrum is similar to that of D-type asteroids. thumb|upright=2.3|Light curve from 25 to 27 October 2017 with dotted line from a model with 10:1 elongation Oumuamua is not rotating around a principal axis, and its motion may be a form of tumbling.Fraser W. C. Pravec P. Fitzsimmons A. Lacerda P. Bannister M. T. Snodgrass C. Smolić I. 119353074 The tumbling rotational state of 1I/Oumuamua Nature Astronomy 2 5 383–386 9 February 2018 10.1038/s41550-018-0398-z 1711.11530 2018NatAs...2..383F https://pure.qub.ac.uk/portal/en/publications/the-tumbling-rotational-state-of-1ioumuamua(cbcc0793-72c1-4f42-b78a-5bcdeff6274c).html 3 September 2018 3 September 2018 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 live 1712.00437 Tumbling motion of 1I/Oumuamua reveals body's violent past Drahus M. Guzik P. Waniak W. Handzlik B. Kurowski S. Xu S. astro-ph.EP 1 December 2017 This accounts for the various rotation periods reported, such as 8.10 hours (±0.42 hours or ±0.02 hours) by Bannister et al. and Bolin et al. with a lightcurve amplitude of 1.5–2.1 magnitudes, whereas Meech et al. reported a rotation period of 7.3 hours and a lightcurve amplitude of 2.5 magnitudes.1865 Cerberus has a lightcurve amplitude of 2.3 magnitudes. Most likely, Oumuamua 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.https://www.bbc.com/news/science-environment-43018706 Oumuamua: 'space cigar's' tumble hints at violent past BBC News Jonathan Amos 11 February 2018 21 July 2018 24 July 2018 https://web.archive.org/web/20180724044444/https://www.bbc.com/news/science-environment-43018706 live thumb|upright=1.5|Simulation of Oumuamua spinning and tumbling through space, and the resultant light curve. In reality, observations of Oumuamua 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 Oumuamua may be anything from a highly elongated cigar-like object, comparable to or greater than the most elongated Solar System objects, to an extremely flat object, a pancake or oblate spheroid.1804.03471 The Excited Spin State of 1I/2017 U1 Oumuamua The Astrophysical Journal 856 2 L21 Belton M. J. S. 119336678 etal 10 April 2018 We find that Oumuamua 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. 10.3847/2041-8213/aab370 2018ApJ...856L..21B free However, the size and shape have not been directly observed as Oumuamua appears as nothing more than a point source of light even in the most powerful telescopes. Neither its albedo nor its triaxial ellipsoid shape is known. If cigar-shaped, the longest-to-shortest axis ratio could be 5:1 or greater. Assuming an albedo of 10% (slightly higher than typical for D-type asteroidsThomas 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 2011AJ....142...85T The Astronomical Journal 142 3 85 10.1088/0004-6256/142/3/85 0004-6256 free ) and a 6:1 ratio, Oumuamua has dimensions of approximately 100 - 1000 x 35 - 167 x 35 - 167 m ft on with an average diameter of about 110 m ft. According to astronomer David C. Jewitt, the object is physically unremarkable except for its highly elongated shape. Bannister et al. have suggested that it could also be a contact binary, although this may not be compatible with its rapid rotation. 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. JPL News reported that Oumuamua "is up to one-quarter mile (400 meters) long and highly-elongated — perhaps 10 times as long as it is wide".Solar System's First Interstellar Visitor Dazzles Scientists https://www.jpl.nasa.gov/news/news.php?feature=7006 Jet Propulsion Laboratory 20 November 2017 20 December 2017 10 March 2020 https://web.archive.org/web/20200310024611/https://www.jpl.nasa.gov/news/news.php?feature=7006 live thumb|Artist's impression of a cigar-shaped Oumuamua 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.Modeling the light curve of Oumuamua: evidence for torque and disc-like shape Monthly Notices of the Royal Astronomical Society Sergey Mashchenko 182952355 489 3 3003–3021 November 2019 10.1093/mnras/stz2380 free 2019MNRAS.489.3003M 1906.03696 Monte Carlo simulations based on the available orbit determination suggest that the equatorial obliquity of Oumuamua 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.de la Fuente Marcos C. de la Fuente Marcos R. Constraining the orientation of the spin axes of extrasolar minor bodies 1I/2017 U1 (Oumuamua) and 2I/Borisov Astronomy and Astrophysics 643 A18 (17 pp) 1 November 2020 10.1051/0004-6361/202037447 free 2009.08423 2020A&A...643A..18D 221761422 https://www.aanda.org/articles/aa/abs/2020/11/aa37447-20/aa37447-20.html 27 October 2020 1 February 2021 https://web.archive.org/web/20210201045557/https://www.aanda.org/articles/aa/abs/2020/11/aa37447-20/aa37447-20.html live A 2021 paper proposed that, if Oumuamua 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 Oumuamua had lost 92% of the mass it had upon entering the Solar System. thumb|left|upright|Color composite image taken on 27 October 2017 using the Gemini South telescope 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://www.science.org/content/article/updated-first-time-astronomers-are-tracking-distant-visitor-streaking-through-our-solar Updated: For the first time, astronomers are tracking a distant visitor streaking through our solar system Science Paul Voosen 20 November 2017 10.1126/science.aar3433 30 November 2017 21 November 2017 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 live https://www.space.com/38838-interstellar-asteroid-oumuamua-space-cigar.html Wow! 1st Interstellar Asteroid Is a Spinning Space Cigar Ian O'Neill Space.com 20 November 2017 30 November 2017 25 April 2020 https://web.archive.org/web/20200425005615/https://www.space.com/38838-interstellar-asteroid-oumuamua-space-cigar.html live It is thought that its surface contains tholins, which are irradiated organic compounds that are more common in objects in the outer Solar System and can help determine the age of the surface.Matt Williams https://www.universetoday.com/137944/interstellar-asteroid-probably-pretty-strange-looking/ That Interstellar Asteroid is probably pretty strange looking Universe Today 20 November 2017 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. 22 December 2017 https://web.archive.org/web/20171222052002/https://www.universetoday.com/137944/interstellar-asteroid-probably-pretty-strange-looking/ live 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/ live https://web.archive.org/web/20171230124909/https://www.universetoday.com/137960/project-lyra-mission-chase-interstellar-asteroid-1/ 30 December 2017 20 December 2017 Universe Today 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 https://web.archive.org/web/20171222052951/https://phys.org/news/2017-11-lyra-mission-interstellar-asteroid.html 22 December 2017 at Phys.org This possibility is inferred from spectroscopic characterization and its reddish color,Fitzsimmons A. C. Snodgrass B. Rozitis B. Yang M. Hyland T. Seccull M. T. Bannister W. C. Fraser R. Jedicke P. Lacerda 216937304 1 Spectroscopy and thermal modelling of the first interstellar object 1I/2017 U1 Oumuamua 1712.06552 18 December 2017 Nature Astronomy 2 2 133 10.1038/s41550-017-0361-4 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 Oumuamua, 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 Oumuamua passed within 0.25 au of the Sun. 2018NatAs...2..133F 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 25 September 2018 17 October 2019 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 live and from the expected effects of interstellar radiation. Despite the lack of any cometary coma when it approached the Sun, it may still contain internal ice, hidden by "an insulating mantle produced by long-term cosmic ray exposure". In November 2019, some astronomers noted that Oumuamua may be a "cosmic dust bunny", due to its "very lightweight and 'fluffy' conglomerate of dust and ice grains".Anderson Paul Scott Was Oumuamua a cosmic dust bunny? https://earthsky.org/space/was-oumuamua-a-cosmic-dust-bunny 26 November 2019 Earth & Sky 27 November 2019 27 November 2019 https://web.archive.org/web/20191127204418/https://earthsky.org/space/was-oumuamua-a-cosmic-dust-bunny live Flekkøy Eirik G. 204734116 et al. The Interstellar Object Oumuamua as a Fractal Dust Aggregate 11 November 2019 The Astrophysical Journal Letters 885 L41 2 10.3847/2041-8213/ab4f78 1910.07135 2019ApJ...885L..41F https://hal-insu.archives-ouvertes.fr/insu-02366685/file/2019-FlekkoyLuuToussaint-Flekk%C3%B8y_2019_ApJL_885_L41.pdf 30 November 2019 1 February 2021 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 live free Tomaswick Andy Okay, New Idea. Oumuamua is an Interstellar 'Dust Bunny' https://www.universetoday.com/147675/okay-new-idea-oumuamua-is-an-interstellar-dust-bunny/ 8 September 2020 Universe Today 9 September 2020 11 September 2020 https://web.archive.org/web/20200911021825/https://www.universetoday.com/147675/okay-new-idea-oumuamua-is-an-interstellar-dust-bunny/ live In August 2020, astronomers reported that Oumuamua is not likely to have been composed of frozen hydrogen, which had been proposed earlier; the compositional nature of the object continues to be unknown.Harvard-Smithsonian Center for Astrophysics and Korea Astronomy and Space Science Institute Scientists determine Oumuamua isn't made from molecular hydrogen ice after all https://phys.org/news/2020-08-scientists-oumuamua-isnt-molecular-hydrogen.html 17 August 2020 Phys.org 17 August 2020 17 August 2020 https://web.archive.org/web/20200817190804/https://phys.org/news/2020-08-scientists-oumuamua-isnt-molecular-hydrogen.html live Hoang Thiem Loeb Abraham Avi Loeb 17 August 2020 Destruction of Molecular Hydrogen Ice and Implications for 1I/2017 U1 (Oumuamua) The Astrophysical Journal Letters 899 L23 2006.08088 2020ApJ...899L..23H 10.3847/2041-8213/abab0c free 2 Radio measurements In December 2017, astronomer Avi Loeb of Harvard University, an adviser to the Breakthrough Listen Project, cited Oumuamua's unusually elongated shape as one reason the Green Bank Telescope in West Virginia would listen for radio emissions from it to see if there were any unexpected signs that it might be of artificial origin, although earlier limited observations by other radio telescopes such as the SETI Institute's Allen Telescope Array had produced no such results. On 13 December 2017, the Green Bank Telescope observed the object for six hours across four bands of radio frequency. No radio signals from Oumuamua were detected in this very limited scanning range, but more observations were planned.Breakthrough Listen Releases Initial Results and Data from Observations of Oumuamua http://breakthroughinitiatives.org/news/15 Breakthrough Listen 13 December 2017 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 15 December 2017 https://web.archive.org/web/20171215053410/http://breakthroughinitiatives.org/news/15 live https://www.theguardian.com/science/2017/dec/14/is-oumuamua-an-alien-spacecraft-first-scans-show-no-signs-of-technology Is Oumuamua an alien spacecraft? Initial scans show no signs of technology The Guardian Ian Sample 15 December 2017 15 December 2017 15 December 2017 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 live 2018 Discussion Nitrogen ice theory Outgassing of nitrogen ice (N2) could explain why no outgassing was detected. Nitrogen ice the size of Oumuamua could survive for 500 million years in the interstellar medium and would reflect two-thirds of the Sun's light.Siegel Ethan 10 February 2021 New Theory Perfectly Explains Oumuamua 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/ live 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/ 13 February 2021 13 February 2021 Forbes en This explanation has been further supported in March 2021 when scientists presented a theory based on nitrogen ice, and further concluded that Oumuamua may be a piece of an exoplanet similar to the dwarf planet Pluto, an exo-Pluto as noted, from beyond the Solar System.Staff 17 March 2021 Scientists determine the origin of extra-solar object Oumuamua Phys.org https://phys.org/news/2021-03-scientists-extra-solar-oumuamua.html 17 March 2021 This theory has been criticized by Loeb.Scientific American https://www.scientificamerican.com/article/was-the-interstellar-object-oumuamua-a-nitrogen-iceberg/ Was the Interstellar Object Oumuamua a Nitrogen Iceberg?2103.14032 Siraj Amir Loeb Abraham The mass budget necessary to explain Oumuamua as a nitrogen iceberg New Astronomy April 2022 92 101730 10.1016/j.newast.2021.101730 2022NewA...9201730S 232352541 In November 2021, theoretical studies by Siraj and Loeb hypothesized that Oumuamua was not a nitrogen iceberg.Hickok Kimberly Interstellar visitor Oumuamua wasn't a nitrogen iceberg, Harvard astrophysicists say - The bizarre interloper called Oumuamua continues to defy explanation. https://www.livescience.com/oumuamua-not-nitrogen-iceberg 15 November 2021 Live Science 15 November 2021 Hydrogen ice theory It has been proposed that Oumuamua contains a significant amount of hydrogen ice.Seligman Darryl Laughlin Gregory Evidence that 1I/2017 U1 (Oumuamua) was Composed of Molecular Hydrogen Ice The Astrophysical Journal 26 May 2020 896 1 L8 10.3847/2041-8213/ab963f 2005.12932 2020ApJ...896L...8S 218900854 free Overbye Dennis Dennis Overbye Oumuamua: Neither Comet nor Asteroid, but a Cosmic Iceberg – A new study suggests the interloper may have arisen in an interstellar cloud, where stars are sometimes born https://www.nytimes.com/2020/06/15/science/oumuamua-astronomy-comets.html 15 June 2020 The New York Times 16 June 2020 16 June 2020 https://web.archive.org/web/20200616003628/https://www.nytimes.com/2020/06/15/science/oumuamua-astronomy-comets.html live This would point to it originating from the core of an interstellar molecular cloud, where conditions for the formation of this material might exist.Hagai B. Perets Ofer Biham Giulio Manico Valerio Pirronello Joe Roser Sol Swords Gianfranco Vidali 29 March 2005 Molecular Hydrogen Formation on Ice Under Interstellar Conditions astro-ph/0412202 The Astrophysical Journal 627 2 850–860 https://www.researchgate.net/publication/230998087 10.1086/430435 2005ApJ...627..850P 56368174 https://web.archive.org/web/20200606012206/https://arxiv.org/abs/astro-ph/0412202 6 June 2020 The Sun's heat would cause the hydrogen to sublime, which would in turn propel the body. The hydrogen coma formed by this process would be difficult to detect from Earth-based telescopes, as the atmosphere blocks those wavelengths.http://www.lpi.usra.edu/education/explore/comets/background/ lpi.usra.edu About Comets 2020-06-06 16 November 2020 https://web.archive.org/web/20201116204514/https://www.lpi.usra.edu/education/explore/comets/background/ live 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 Oumuamua 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 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.Hoang Thiem Loeb Abraham Avi Loeb 2020 Destruction of molecular hydrogen ice and Implications for Oumuamua The Astrophysical Journal Letters 899 2 2006.08088 10.3847/2041-8213/abab0c 2020ApJ...899L..23H 219687520 free Letzer Ran Interstellar visitor Oumuamua could still be alien technology, new study hints – Aliens? Or a chunk of solid hydrogen? Which idea makes less sense? https://www.livescience.com/oumuamua-interstellar-hydrogen-or-aliens.html 19 August 2020 Live Science 6 January 2021 9 January 2021 https://web.archive.org/web/20210109012743/https://www.livescience.com/oumuamua-interstellar-hydrogen-or-aliens.html live Hydrogen-laden water ice theory In 2023, it was proposed the observed non-gravitational acceleration and spectrum of Oumuamua 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 by cosmic ray particles while Oumuamua or similar cometary body was in interstellar space.2303.13698 2023 Acceleration of 1I/Oumuamua from radiolytically produced H2 in H2O ice 10.1038/s41586-022-05687-w Bergner Jennifer B. Seligman Darryl Z. Nature 615 7953 610–613 36949336 257668585 Hypothetical space missions Project Lyra Interstellar object#Hypothetical missions The Initiative for Interstellar Studies (i4is) launched Project Lyra to assess the feasibility of a mission to Oumuamua.Project Lyra – A Mission to Oumuamua https://i4is.org/what-we-do/technical/project-lyra/ I4IS Initiative for Interstellar Studies 3 December 2017 3 December 2017 https://web.archive.org/web/20171203224457/https://i4is.org/what-we-do/technical/project-lyra/ live Several options for sending a spacecraft to Oumuamua within a time-frame of 5 to 25 years were suggested.Williams Matt If Launched by 2028, a Spacecraft Could Catch up With Oumuamua in 26 Years https://www.universetoday.com/154028/if-launched-by-2028-a-spacecraft-could-catch-up-with-oumuamua-in-26-years/ 20 January 2022 Universe Today 27 January 2022 Hibberd, Adam et al. 11 January 2022 Project Lyra: A mission to 1I/Oumuamua without Solar Oberth Manoeuvre Acta Astronautica 199 161–165 10.1016/j.actaastro.2022.07.032 2201.04240 2022AcAau.199..161H 245877397 Hein Andreas M. Perakis Nikolaos Eubanks T. Marshall Hibberd Adam Crowl Adam Hayward Kieran Kennedy III Robert G. Osborne Richard Project Lyra: Sending a spacecraft to 1I/Oumuamua (former A/2017 U1), the interstellar asteroid Acta Astronautica 7 January 2019 161 552 10.1016/j.actaastro.2018.12.042 1711.03155 2019AcAau.161..552H 119474144 Hibberd Adam Hein Andreas M. Eubanks T. Marshall 119078436 Project Lyra: Catching 1I/Oumuamua – Mission Opportunities After 2024 Acta Astronautica 170 136–144 1902.04935 10.1016/j.actaastro.2020.01.018 2020AcAau.170..136H 2020 Different mission durations and their velocity requirements were explored with respect to the launch date, assuming direct impulsive transfer to the intercept trajectory.February 2021 The Space Launch System (also being looked at for "interstellar precursor missions") would be even more capable.https://www.hou.usra.edu/meetings/lpsc2015/pdf/2346.pdf The Space Launch System and Missions to the Outer Solar System 46th Lunar and Planetary Science Conference. 16–20 March 2015. The Woodlands, Texas. K. Klaus 2015 5 June 2019 26 October 2020 https://web.archive.org/web/20201026105533/https://www.hou.usra.edu/meetings/lpsc2015/pdf/2346.pdf live https://www.researchgate.net/publication/285199699 Enabling interstellar probe with the Space Launch System (SLS) 65th International Astronautical Congress. 29 September-3 October 2014. Toronto, Canada. R. L. Jr. McNutt M. S. Elsperman Mike Gruntman K. K. Klaus S. M. Krimigis E. C. Roelof D. B. Smith S. R. Vernon R. F. Wimmer-Schweingruber 1 2014 5 June 2019 1 February 2021 https://web.archive.org/web/20210201045618/https://www.researchgate.net/publication/285199699_Enabling_interstellar_probe_with_the_Space_Launch_System_SLS live Such an interstellar precursor could easily pass by Oumuamua on its way out of the Solar System, at speeds of 63 km/s mi/s on.https://studylib.net/doc/18163873/sls-mission-booklet Space Launch System: Mission Booklet Boeing Studylib.net 2013 5 June 2019 5 June 2019 https://web.archive.org/web/20190605183847/https://studylib.net/doc/18163873/sls-mission-booklet live https://www.kiss.caltech.edu/workshops/ism/presentations/KISS%20How%20Fast%20How%20Far_strange_final.pdf An Architectural Framework for the design of missions to explore the ISM NASA/Jet Propulsion Laboratory Nitin Arora Nathan Strange Robert Cesarone Leon Alkalai 1 2014 25 October 2019 1 September 2020 https://web.archive.org/web/20200901100315/https://www.kiss.caltech.edu/workshops/ism/presentations/KISS%20How%20Fast%20How%20Far_strange_final.pdf live More advanced options of using solar, laser electric, and laser sail propulsion, based on 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 Oumuamua would be "highly desirable, due to the minimal science return from a hyper-velocity encounter". 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. 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.Seligman Darryl Laughlin Gregory 73656586 The Feasibility and Benefits of in situ Exploration of Oumuamua-like Objects The Astronomical Journal 155 5 217 12 April 2018 1803.07022 10.3847/1538-3881/aabd37 2018AJ....155..217S free Technosignature hypothesis On 26 October 2018, Loeb and his post-doctoral researcher, Shmuel Bialy, submitted a paper exploring the possibility of Oumuamua being an artificial thin solar sailhttps://www.haaretz.com/us-news/2019-01-16/ty-article-magazine/.premium/if-true-this-could-be-one-of-the-greatest-discoveries-in-human-history/0000017f-e880-df5f-a17f-fbde98f70000 If True, This Could Be One of the Greatest Discoveries in Human History Carmeli Oded 14 January 2019 Haaretz en 14 January 2019 14 January 2019 https://web.archive.org/web/20190114154442/https://www.haaretz.com/world-news/.premium.MAGAZINE-if-true-this-could-be-one-of-the-greatest-discoveries-in-human-history-1.6828318 live Selik Avi Alien ship may be among us, Harvard astronomer insists, despite grumbling and criticism from peers https://www.chicagotribune.com/news/nationworld/science/ct-harvard-astronomer-aliens-20190204-story.html 4 February 2019 ChicagoTribune 5 February 2019 5 February 2019 https://web.archive.org/web/20190205085137/https://www.chicagotribune.com/news/nationworld/science/ct-harvard-astronomer-aliens-20190204-story.html live accelerated by solar radiation pressure, in an effort to help explain the object's comet-like non-gravitational acceleration.Williams Matt Could Oumuamua Be an Extra-Terrestrial Solar Sail? https://www.universetoday.com/140391/could-oumuamua-be-an-extra-terrestrial-solar-sail/ 2 November 2018 Universe Today 2 November 2018 3 November 2018 https://web.archive.org/web/20181103042615/https://www.universetoday.com/140391/could-oumuamua-be-an-extra-terrestrial-solar-sail/ live Bialy Shmuel Loeb Abraham 118956077 Could Solar Radiation Explain Oumuamua's Peculiar Acceleration? The Astrophysical Journal 868 L1 26 October 2018 1 1810.11490 10.3847/2041-8213/aaeda8 2018ApJ...868L...1B free Loeb Abraham How to Search for Dead Cosmic Civilizations https://blogs.scientificamerican.com/observations/how-to-search-for-dead-cosmic-civilizations/ 26 September 2018 Scientific American 26 September 2018 27 April 2020 https://web.archive.org/web/20200427025843/https://blogs.scientificamerican.com/observations/how-to-search-for-dead-cosmic-civilizations/ live Other scientists have stated that the available evidence is insufficient to consider such a premise,Sheridan Kerry 7 November 2018 Scientists push back against Harvard 'alien spacecraft' theory https://phys.org/news/2018-11-scientists-harvard-alien-spacecraft-theory.html live https://web.archive.org/web/20210123055305/https://phys.org/news/2018-11-scientists-harvard-alien-spacecraft-theory.html 23 January 2021 14 February 2021 Phys.orghttps://www.yahoo.com/news/oumuamua-oh-interstellar-object-actually-225825249.html Oumuamua, oh my! Was interstellar object actually an alien solar sail? Not so fast Boyle Alan 6 November 2018 Yahoo! 8 November 2018 8 November 2018 https://web.archive.org/web/20181108224820/https://www.yahoo.com/news/oumuamua-oh-interstellar-object-actually-225825249.html live Schadwinkel Alina 8 November 2018 Glaubt dieser Harvard-Professor selbst, was er sagt? de Zeit Online https://www.zeit.de/wissen/2018-11/oumuamua-lichtsegel-ausserirdische-aliens live 8 November 2018 https://web.archive.org/web/20181108172742/https://www.zeit.de/wissen/2018-11/oumuamua-lichtsegel-ausserirdische-aliens 8 November 2018 and that a tumbling solar sail would not be able to accelerate.https://www.wpsdlocal6.com/archive/cigar-shaped-interstellar-object-may-have-been-an-alien-probe/article_24c3cd57-36e8-580a-87e1-f139ab01d53d.html Cigar-shaped interstellar object may have been an alien probe, Harvard paper claims WPSD Local 6 CNN 6 November 2018 25 October 2019 25 October 2019 https://web.archive.org/web/20191025043903/https://www.wpsdlocal6.com/archive/cigar-shaped-interstellar-object-may-have-been-an-alien-probe/article_24c3cd57-36e8-580a-87e1-f139ab01d53d.html live In response, Loeb wrote an article detailing six anomalous properties of Oumuamua that make it unusual, unlike any comets or asteroids seen before 2018, and published a public science book in 2021 about the state of the discussion.Loeb Abraham Avi Loeb 6 Strange Facts about the Interstellar Visitor Oumuamua https://blogs.scientificamerican.com/observations/6-strange-facts-about-the-interstellar-visitor-oumuamua/ 20 November 2018 Scientific American 20 November 2018 20 November 2018 https://web.archive.org/web/20181120233035/https://blogs.scientificamerican.com/observations/6-strange-facts-about-the-interstellar-visitor-oumuamua/ live Chotiner Isaac Have Aliens Found Us? A Harvard Astronomer on the Mysterious Interstellar Object Oumuamua https://www.newyorker.com/news/the-new-yorker-interview/have-aliens-found-us-a-harvard-astronomer-on-the-mysterious-interstellar-object-oumuamua 16 January 2019 The New Yorker 16 January 2019 16 January 2019 https://web.archive.org/web/20190116185121/https://www.newyorker.com/news/the-new-yorker-interview/have-aliens-found-us-a-harvard-astronomer-on-the-mysterious-interstellar-object-oumuamua live The solar sail technosignature hypothesis is considered unlikely by many experts owing to available simpler explanations that align with the expected characteristics of interstellar asteroids and comets.Wright Jason T. Desch Steven Raymond Sean 18 July 2023 Oumuamua: Natural or Artificial? Medium https://medium.com/@astrowright/oumuamua-natural-or-artificial-f744b70f40d5 live 27 July 2023 https://archive.today/20230721033228/https://medium.com/@astrowright/oumuamua-natural-or-artificial-f744b70f40d5 21 July 20232102.07871 Oumuamua is not Artificial Katz J. I. 15 February 2021 physics.pop-ph Other interstellar objects Interstellar object 2I/Borisov was discovered on 30 August 2019, and was soon confirmed to be an interstellar comet. Arriving from the direction of Cassiopeia, the object arrived at perihelion (closest point to the Sun) on 8 December 2019. 3I/ATLAS was discovered on 1 July 2025. It arrived with a hyperbolic excess velocity of 58 km/s. Other proposed interstellar objects include the meteors CNEOS 2014-01-08Pultarova Tereza Confirmed! A 2014 meteor is Earth's 1st known interstellar visitor - Interstellar space rocks might be falling to Earth every 10 years. https://www.space.com/2014-meteor-first-interstellar-visitor-oumuamua 3 November 2022 Space.com 4 November 2022 and CNEOS 2017-03-09 that impacted Earth in 2014Ferreira Becky Secret Government Info Confirms First Known Interstellar Object on Earth, Scientists Say - A small meteor that hit Earth in 2014 was from another star system, and may have left interstellar debris on the seafloor. https://www.vice.com/en/article/secret-government-info-confirms-first-known-interstellar-object-on-earth-scientists-say/ 7 April 2022 Vice News 9 April 2022 Wenz John "It Opens A New Frontier Where You're Using The Earth As A Fishing Net For These Objects." - Harvard Astronomer Believes An Interstellar Meteor (or Craft) Hit Earth In 2014 https://www.inverse.com/science/interstellar-meteor-2014-discovery 11 April 2022 Inverse 11 April 2022 Siraj Amir Loeb Abraham Discovery of a Meteor of Interstellar Origin 4 June 2019 astro-ph.EP 1904.07224 Handal Josh Fox Karen Talbert Tricia 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 8 April 2022 NASA 11 April 2022 and 2017, respectively,Loeb Avi The discovery of a second interstellar meteor https://thedebrief.org/the-discovery-of-a-second-interstellar-meteor/ 23 September 2022 TheDebrief.org 24 September 2022 although these claims have been met with skepticism.Richtel Matt 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 11 March 2024 The New York Times live https://archive.today/20240311121317/https://www.nytimes.com/2024/03/11/science/meteor-avi-loeb.html 11 March 2024 11 March 2024 See also C/1980 E1 (Bowell) – the most eccentric comet known in the Solar System with an eccentricity of 1.057 514107 Kaepaokaāwela, an asteroid of possible interstellar origin C/2017 U7, a non-interstellar hyperbolic comet discovered 10 days after Oumuamua, announced in March 2018 C/2018 C2, another non-interstellar hyperbolic comet, announced in March 2018 Extraterrestrial: The First Sign of Intelligent Life Beyond Earth, a 2021 book by Avi Loeb describing the Oumuamua technosignature hypothesis Rendezvous with Rama, a 1973 Arthur C. Clarke science-fiction novel about intercepting a large cylindrical spacecraft transiting the Solar System 3I/ATLAS, the third interstellar comet discovered in 2025 in the Solar System Notes References MPEC 2017-U181: COMET C/2017 U1 (PANSTARRS) http://www.minorplanetcenter.net/mpec/K17/K17UI1.html Minor Planet Center International Astronomical Union 25 October 2017 25 October 2017 25 October 2017 https://web.archive.org/web/20171025184710/http://www.minorplanetcenter.net/mpec/K17/K17UI1.html live (CK17U010) Antier K. A/2017 U1, first interstellar asteroid ever detected! https://www.imo.net/a2017-u1-first-interstellar-asteroid-ever-detected/ International Meteor Organization 30 October 2017 7 November 2017 7 November 2017 https://web.archive.org/web/20171107004829/https://www.imo.net/a2017-u1-first-interstellar-asteroid-ever-detected/ live Pseudo-MPEC for A/2017 U1 (FAQ File) https://projectpluto.com/temp/2017u1.htm Bill Gray of Project Pluto 26 October 2017 26 October 2017 26 October 2017 https://web.archive.org/web/20171026214746/https://projectpluto.com/temp/2017u1.htm live (Orbital elements) https://web.archive.org/web/20180930231741/https://projectpluto.com/temp/2017u1_a.htm#elements 30 September 2018 JPL Small-Body Database Browser: Oumuamua (A/2017 U1) https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1I&view=OPC live JPL Small-Body Database Jet Propulsion Laboratory 19 March 2021 https://web.archive.org/web/20210121065013/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1I 21 January 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) 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 Hawaiian Dictionary Pukui M.K. Elbert S.H. Ulukau: Hawaiian Electronic Library University of Hawaii Press 2003 21 November 2017 1 February 2021 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 live 1I/Oumuamua = A/2017 U1 Orbit Minor Planet Center International Astronomical Union https://www.minorplanetcenter.net/db_search/show_object?object_id=1I 9 November 2017 4 January 2018 https://web.archive.org/web/20180104073303/https://www.minorplanetcenter.net/db_search/show_object?object_id=1I live Astronomers Spot First-Known Interstellar Comet http://www.skyandtelescope.com/astronomy-news/astronomers-spot-first-known-interstellar-comet/ Sky & Telescope Beatty Kelly 25 October 2017 25 October 2017 26 October 2017 https://wayback.archive-it.org/all/20171026001610/http://www.skyandtelescope.com/astronomy-news/astronomers-spot-first-known-interstellar-comet/ live MPEC 2017-U183: A/2017 U1 http://www.minorplanetcenter.net/mpec/K17/K17UI3.html Minor Planet Center International Astronomical Union 25 October 2017 25 October 2017 26 October 2017 https://web.archive.org/web/20171026054257/http://www.minorplanetcenter.net/mpec/K17/K17UI3.html live (AK17U010) MPEC 2017-U185: A/2017 U1 http://www.minorplanetcenter.net/mpec/K17/K17UI5.html Minor Planet Center International Astronomical Union 26 October 2017 26 October 2017 1 November 2017 https://web.archive.org/web/20171101170918/http://www.minorplanetcenter.net/mpec/K17/K17UI5.html live JPL Small-Body Database Search Engine – Constraints: e > 1 JPL Small-Body Database Jet Propulsion Laboratory 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 26 October 2017 9 December 2019 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 live 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 26 October 2017 29 October 2017 2 December 2017 https://web.archive.org/web/20171202092239/https://www.nasa.gov/feature/jpl/small-asteroid-or-comet-visits-from-beyond-the-solar-system/ live Interstellar Asteroid FAQs https://www.nasa.gov/planetarydefense/faq/interstellar NASA 20 November 2017 21 November 2017 18 December 2019 https://web.archive.org/web/20191218124241/https://www.nasa.gov/planetarydefense/faq/interstellar/ live Mamajek Eric 2017 Kinematics of the Interstellar Vagabond A/2017 U1 1710.11364 astro-ph.EP Portegies Zwart S. I. Pelupessy J. Bedorf M. Cai S. Torres 56249057 The origin of interstellar asteroidal objects like 1I/2017 U1 Monthly Notices of the Royal Astronomical Society: Letters 479 1 L17–L22 9 November 2017 1711.03558 10.1093/mnrasl/sly088 free 2018MNRAS.479L..17P Gaidos E. J.P. Williams A. Kraus 2017 Origin of Interstellar Object A/2017 U1 in a Nearby Young Stellar Association? Research Notes of the AAS 1 1 13 1711.01300 2017RNAAS...1...13G 10.3847/2515-5172/aa9851 119091790 free A.M. Hein N. Perakis K.F. Long A. Crowl M. Eubanks R.G. III Kennedy R. Osborne 2017 Project Lyra: Sending a Spacecraft to 1I/Oumuamua (former A/2017 U1), the Interstellar Asteroid 1711.03155 physics.space-ph 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 6 November 2017 8 January 2020 https://web.archive.org/web/20200108040032/https://www.minorplanetcenter.net/mpec/K17/K17V17.html live Bolin B.T. H.A. Weaver Y.R. Fernandez C.M. Lisse D. Huppenkothen R.L. Jones M. Juric J. Moeyens C.A. Schambeau C.T. Slater Z. Ivezic A.J. Connolly 118894742 1 2017 APO Time Resolved Color Photometry of Highly-Elongated Interstellar Object 1I/Oumuamua The Astrophysical Journal 852 1 L2 1711.04927 10.3847/2041-8213/aaa0c9 2018ApJ...852L...2B free Jewitt D. J. Luu J. Rajagopal R. Kotulla S. Ridgway W. Liu T. Augusteijn 32684355 Interstellar Interloper 1I/2017 U1: Observations from the NOT and WIYN Telescopes The Astrophysical Journal Letters 850 2 L36 1711.05687 30 November 2017 10.3847/2041-8213/aa9b2f 2017ApJ...850L..36J free Jewitt D. D. Seligman Interstellar Interlopers Annual Review of Astronomy and Astrophysics 2209.08182 2023 61 197 10.1146/annurev-astro-071221-054221 2023ARA&A..61..197J A Familiar-Looking Messenger from Another Solar System National Optical Astronomy Observatory https://www.noao.edu/news/2017/pr1706.php 15 November 2017 NOAO 17-06 15 November 2017 16 November 2017 https://web.archive.org/web/20171116133909/https://www.noao.edu/news/2017/pr1706.php live Ye Q.-Z. Zhang Q. 119392232 5 December 2017 1I/Oumuamua is Hot: Imaging, Spectroscopy and Search of Meteor Activity The Astrophysical Journal Letters 851 1 L5 1711.02320 10.3847/2041-8213/aa9a34 2017ApJ...851L...5Y https://authors.library.caltech.edu/83727/1/Ye_2017_ApJL_851_L5.pdf 3 November 2018 23 July 2018 https://web.archive.org/web/20180723033917/https://authors.library.caltech.edu/83727/1/Ye_2017_ApJL_851_L5.pdf live free Bannister M.T. Schwamb M.E. 56264680 2017 Col-OSSOS: Colors of the Interstellar Planetesimal 1I/2017 U1 in Context with the Solar System The Astrophysical Journal 851 2 L38 1711.06214 As its albedo is unknown, we do not describe 1I/Oumuamua as consistent with Tholen (1984) P type. 10.3847/2041-8213/aaa07c 2017ApJ...851L..38B free ESO Karen Meech et al Light curve of interstellar asteroid Oumuamua 20 November 2017 https://www.eso.org/public/images/eso1737f/ European Southern Observatory 21 November 2017 19 December 2019 https://web.archive.org/web/20191219152200/https://www.eso.org/public/images/eso1737f/ live 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 Research Notes of the AAS 1 1 5 1711.00445 2017RNAAS...1....5D 10.3847/2515-5172/aa96b4 119537175 free Proposal 15405 – Which way home? Finding the origin of our Solar System's first interstellar visitor Karen Meech et al STScI – Space Telescope Science Institute http://www.stsci.edu/hst/phase2-public/15405.pdf 8 November 2017 15 November 2017 1 Meech K.J. Weryk R. Micheli M. Kleyna J.T. Hainaut O.R. Jedicke R. Wainscoat R.J. Chambers K.C. Keane J.V. A. Petric L. Denneau E. Magnier T. Berger M.E. Huber H. Flewelling C. Waters E. Schunova-Lilly S. Chastel 4393243 20 November 2017 A brief visit from a red and extremely elongated interstellar asteroid Nature 552 7685 378–381 10.1038/nature25020 29160305 8979573 2017Natur.552..378M https://www.theguardian.com/science/2017/dec/11/astronomers-to-check-interstellar-body-for-signs-of-alien-technology Astronomers to check interstellar body for signs of alien technology Ian Sample The Guardian 11 December 2017 Green Bank telescope in West Virginia will listen for radio signals from Oumuamua, 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 Oumuamua 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. 12 December 2017 25 April 2020 https://web.archive.org/web/20200425025003/https://www.theguardian.com/science/2017/dec/11/astronomers-to-check-interstellar-body-for-signs-of-alien-technology live 923928561722982400 FitzsimmonsAlan Spectrum of A/2017 U1 obtained on Wednesday night with the @INGLaPalma 4.2m WHT. Colour is red like Kuiper Belt Objects, featureless. 27 October 2017 Alan Fitzsimmons en-GB https://www.theatlantic.com/science/archive/2017/12/yuri-milner-oumuamua-interstellar-asteroid/547985/ Astronomers to Check Mysterious Interstellar Object for Signs of Technology The Atlantic Marina Koren 11 December 2017 11 December 2017 11 December 2017 https://web.archive.org/web/20171211201521/https://www.theatlantic.com/science/archive/2017/12/yuri-milner-oumuamua-interstellar-asteroid/547985/ live https://www.scientificamerican.com/article/alien-probe-or-galactic-driftwood-seti-tunes-in-to-oumuamua/ Alien Probe or Galactic Driftwood? SETI Tunes In to Oumuamua Scientific American Lee Billings 11 December 2017 12 December 2017 So far limited observations of Oumuamua, using facilities such as the SETI Institute's Allen Telescope Array, have turned up nothing. 14 December 2017 https://web.archive.org/web/20171214003318/https://www.scientificamerican.com/article/alien-probe-or-galactic-driftwood-seti-tunes-in-to-oumuamua/ live http://www.eso.org/public/news/eso1820/ ESO's VLT Sees Oumuamua Getting a Boost – New results indicate interstellar nomad Oumuamua is a comet 27 June 2018 www.eso.org en-GB Such outgassing is a behaviour typical for comets and contradicts the previous classification of Oumuamua as an interstellar asteroid. "We think this is a tiny, weird comet," commented 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." 28 June 2018 3 July 2018 https://web.archive.org/web/20180703210038/http://eso.org/public/news/eso1820/ live Non-gravitational acceleration in the trajectory of 1I/2017 U1 (Oumuamua) Nature 559 7713 223–226 2018 10.1038/s41586-018-0254-4 29950718 Micheli M. Farnocchia D. Meech K.J. Buie M.W. Hainaut O.R. Prialnik D. Schörghofer N. Weaver H.A. Chodas P.W. Kleyna J.T. Weryk R. Wainscoat R.J. Ebeling H. Keane J.V. Chambers K.C. Koschny D. Petropoulos A.E. 49477508 1 2018Natur.559..223M Witze Alexandra Mysterious interstellar visitor is a comet – not an asteroid – Quirks in Oumuamua's path through the Solar System helped researchers solve a case of mistaken identity https://www.nature.com/articles/d41586-018-05552-9 27 June 2018 Nature 10.1038/d41586-018-05552-9 126317359 27 June 2018 27 June 2018 https://web.archive.org/web/20180627181835/https://www.nature.com/articles/d41586-018-05552-9 live subscription Cofield Calla Chou Felicia Wendel JoAnna Weaver Donna Villard Ray Our Solar System's First Known Interstellar Object Gets Unexpected Speed Boost https://www.jpl.nasa.gov/news/news.php?feature=7173 27 June 2018 NASA 27 June 2018 27 June 2018 https://web.archive.org/web/20180627194643/https://www.jpl.nasa.gov/news/news.php?feature=7173 live External links 1I/Oumuamua https://solarsystem.nasa.gov/small-bodies/asteroids/oumuamua/in-depth/ Oumuamua: The first known interstellar object to visit our solar system. 29 November 2017 NASA.gov Where is Oumuamua in the sky: The Sky Live Talk about A/2017 U1 from 31 October 2017. SETI Institute at Facebook Live. k7y65DyrsbY Interstellar Asteroid A/2017 U1 (update 7 November 2017) (time 3:31 min.) http://ssc.spitzer.caltech.edu/warmmission/scheduling/approvedprograms/ddt/13249.txt Spitzer DDT observations of the interstellar comet A/2017 U1 Caltech.edu Proposal #13249 http://exoplanet.eu/catalog/1i/2017_u1/ Planet 1I/2017 U1 8 November 2017 8 November 2017 Extrasolar Planets Encyclopaedia https://web.archive.org/web/20171108035255/http://exoplanet.eu/catalog/1i/2017_u1/ "A piece of an extrasolar Pluto may have passed through our cosmic neighborhood, a new study suggests.", article by Dennis Overbye, New York Times, Updated March 29, 2021 https://www.nytimes.com/video/science/100000005592208/glimpse-of-oumuamua.html Video – 2:53 A Glimpse of Oumuamua Narrated by Dennis Overbye; Produced by Jonathan Corum and Jason Drakeford The New York Times 12 December 2017 Science fiction story about Oumuamua by astronomer Andrew Fraknoi Interactive 3D gravity simulation of Oumuamua's Solar System flyby https://web.archive.org/web/20200903042335/https://gravitysimulator.org/solar-system/oumuamua/ 3 September 2020 Astronomy Stars Spaceflight Solar System 20171018 Category:Discoveries by Pan-STARRS Category:Hyperbolic asteroids 1I Category:Milky Way Category:Near-Earth objects in 2017