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Oumuamua Interstellar Object

Astronomy

Pan-STARRS discovered a fast-moving interstellar object in 2017, follow-up scans traced its strange trajectory

Witnesses — Pan-STARRS1 survey team, global observatories, Breakthrough Listen radio campaign

Evidence — Optical imaging, Spectroscopic measurements, Radio scans, Infrared search, Non-gravitational trajectory

Status — Unresolved

Disclosure Rating — 8/10

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.

Breakthrough 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.

  Timeline

DateEventSource
19 Oct 2017Robert Weryk identifies fast-moving object in Pan-STARRS1 images1
25 Oct 2017Orbit confirmed hyperbolic; classification changed from comet to asteroid2
6 Nov 2017Named 1I/'Oumuamua by IAU Minor Planet Center3
13 Dec 2017Breakthrough Listen begins radio scans using Green Bank Telescope4
Jun 2018Hubble tracking reveals non-gravitational acceleration5
Nov 2018Spitzer data show no infrared detection, constraining size6

  Observational data

  • Pan-STARRS and VLT images show an elongated reddish body roughly a hundred metres long.
  • Spectroscopic studies detect no coma, implying a dry surface or depleted volatiles.
  • Breakthrough Listen and other radio campaigns report silence across multiple bands.
  • Spitzer and other infrared telescopes provide only upper limits on diameter.

  References

  1. Minor Planet Center – MPEC 2017-V17 ↩

  2. NASA JPL – Small-Body Database 1I/2017 U1 ↩

  3. IAU – Press Release 1719 ↩

  4. Breakthrough Listen – Initial results from observations of 'Oumuamua ↩

  5. Micheli et al. 2018, Nature – Non-gravitational acceleration in 1I/'Oumuamua ↩

  6. JPL – Spitzer telescope reveals interstellar object could be a comet ↩

Occured on October 19, 2017

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