{"type":"events","slug":"2017-oumuamua-interstellar-object","title":"Oumuamua Interstellar Object","url":"https://disclosdex.com/events/2017-oumuamua-interstellar-object","description":"Pan-STARRS discovered a fast-moving interstellar object in 2017, follow-up scans traced its strange trajectory","date":"2017-10-19T00:00:00.000Z","tags":["Astronomy"],"updated":"2025-06-13T13:26:43.000Z","disclosureRating":8,"status":"unresolved","lat":20.7097,"lng":-156.2532,"connectionCount":1,"content":{"markdown":"Haleakal\\u0101-based Pan-STARRS1 detected object A/2017 U1 on 19 October 2017. Rapid follow-up revealed a hyperbolic orbit unlike any Solar System body. The International Astronomical Union soon redesignated the object 1I/'Oumuamua, meaning \"scout\" in Hawaiian. Telescopes worldwide scrambled to record photometry and spectra showing a reddish, elongated body with no visible coma.\n\nBreakthrough Listen used the Green Bank Telescope in December 2017 to search for radio emissions. None were found. A 2018 *Nature* paper reported a non-gravitational acceleration, suggesting volatile outgassing. Subsequent Spitzer observations failed to detect an infrared signature, implying a small size or high reflectivity. The object's true nature remains uncertain, fueling speculation about its origin.\n\n## Timeline\n\n| Date | Event | Source |\n| ---- | ----- | ------ |\n| 19 Oct 2017 | Robert Weryk identifies fast-moving object in Pan-STARRS1 images | [^1] |\n| 25 Oct 2017 | Orbit confirmed hyperbolic; classification changed from comet to asteroid | [^2] |\n| 6 Nov 2017 | Named 1I/'Oumuamua by IAU Minor Planet Center | [^3] |\n| 13 Dec 2017 | Breakthrough Listen begins radio scans using Green Bank Telescope | [^4] |\n| Jun 2018 | Hubble tracking reveals non-gravitational acceleration | [^5] |\n| Nov 2018 | Spitzer data show no infrared detection, constraining size | [^6] |\n\n## Observational data\n\n- Pan-STARRS and VLT images show an elongated reddish body roughly a hundred metres long.\n- Spectroscopic studies detect no coma, implying a dry surface or depleted volatiles.\n- Breakthrough Listen and other radio campaigns report silence across multiple bands.\n- Spitzer and other infrared telescopes provide only upper limits on diameter.\n\n[^1]: IAU – [The IAU approves new type of designation for interstellar objects](https://iauarchive.eso.org/news/announcements/detail/ann17045/)\n[^2]: Minor Planet Center – [MPEC 2017-U181](https://www.minorplanetcenter.net/mpec/K17/K17UI1.html) and [MPEC 2017-U183](https://www.minorplanetcenter.net/mpec/K17/K17UI3.html)\n[^3]: Minor Planet Center – [MPEC 2017-V17](https://www.minorplanetcenter.net/mpec/K17/K17V17.html)\n[^4]: Breakthrough Listen – [Initial results from observations of 'Oumuamua](https://breakthroughinitiatives.org/news/15)\n[^5]: Micheli et al. 2018, *Nature* – [Non-gravitational acceleration in 1I/'Oumuamua](https://www.nature.com/articles/s41586-018-0254-4)\n[^6]: JPL – [NASA learns more about interstellar visitor 'Oumuamua](https://www.jpl.nasa.gov/news/nasa-learns-more-about-interstellar-visitor-oumuamua/)","readingTime":"2 min read"},"relatedRecords":[{"ref":{"type":"people","slug":"avi-loeb","title":"Avi Loeb","url":"https://disclosdex.com/people/avi-loeb"},"direction":"inbound","weight":1}],"citation":{"canonicalUrl":"https://disclosdex.com/events/2017-oumuamua-interstellar-object","title":"Oumuamua Interstellar Object","publisher":"Disclosdex","retrievedFrom":"https://disclosdex.com/api/v1/events/2017-oumuamua-interstellar-object","license":"CC-BY-4.0"},"witnesses":["Pan-STARRS1 survey team","global observatories","Breakthrough Listen radio campaign"],"evidence":["optical imaging","spectroscopic measurements","radio scans","infrared search","non-gravitational trajectory"]}