Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

A retrograde co-orbital asteroid of Jupiter


Recent theoretical work in celestial mechanics has revealed that an asteroid may orbit stably in the same region as a planet, despite revolving around the Sun in the sense opposite to that of the planet itself1,2,3,4,5. Asteroid 2015 BZ509 was discovered6 in 2015, but with too much uncertainty in its measured orbit to establish whether it was such a retrograde co-orbital body. Here we report observations and analysis that demonstrates that asteroid 2015 BZ509 is indeed a retrograde co-orbital asteroid of the planet Jupiter. We find that 2015 BZ509 has long-term stability, having been in its current, resonant state for around a million years. This is long enough to preclude precise calculation of the time or mechanism of its injection to its present state, but it may be a Halley-family comet that entered the resonance through an interaction with Saturn. Retrograde co-orbital asteroids of Jupiter and other planets may be more common than previously expected.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Prices vary by article type



Prices may be subject to local taxes which are calculated during checkout

Figure 1: The path of asteroid 2015 BZ509 in the frame that rotates with Jupiter.
Figure 2: The 1:−1 resonant argument of asteroid 2015 BZ509 with respect to Jupiter.


  1. Dobrovolskis, A. R. Counter-orbitals: another class of co-orbitals. AAS/Division of Planetary Sciences Meeting 44, abstr. 112.22 (2012)

    ADS  Google Scholar 

  2. Morais, M. H. M. & Giuppone, C. A. Stability of prograde and retrograde planets in circular binary systems. Mon. Not. R. Astron. Soc. 424, 52–64 (2012)

    Article  ADS  Google Scholar 

  3. Morais, M. H. M. & Namouni, F. Retrograde resonance in the planar three-body problem. Celestial Mech. Dyn. Astron. 117, 405–421 (2013)

    Article  ADS  MathSciNet  Google Scholar 

  4. Namouni, F. & Morais, M. H. M. Resonance capture at arbitrary inclination. Mon. Not. R. Astron. Soc. 446, 1998–2009 (2015)

    Article  ADS  Google Scholar 

  5. Morais, M. H. M. & Namouni, F. A numerical investigation of co-orbital stability and libration in three dimensions. Celestial Mech. Dyn. Astron. 125, 91–106 (2016)

    Article  ADS  Google Scholar 

  6. Kaiser, N. Pan-STARRS: a wide-field optical survey telescope array. In Proc. SPIE Vol. 5489 (ed. Oschmann, J. M. Jr ) 11–23 (SPIE, 2004)

    Article  ADS  Google Scholar 

  7. Levison, H. Comet taxonomy. In ASP Conf. Ser. Vol. 107 (eds Rettig, T. W. & Hahn, J. M. ) 173–191 (Astronomical Society of the Pacific, 1996)

    ADS  Google Scholar 

  8. Nesvorný, D., Alvarellos, J. L. A., Dones, L. & Levison, H. F. Orbital and collisional evolution of the irregular satellites. Astron. J. 126, 398–429 (2003)

    Article  ADS  Google Scholar 

  9. de Pater, I. & Lissauer, J. J. Planetary Sciences (Cambridge Univ. Press, 2005)

  10. Morais, M. H. M. & Namouni, F. Asteroids in retrograde resonance with Jupiter and Saturn. Mon. Not. R. Astron. Soc. 436, L30–L34 (2013)

    Article  ADS  Google Scholar 

  11. Hatzes, A. The architecture of exoplanets. Space Sci. Rev. 205, 267–283 (2016)

    Article  ADS  Google Scholar 

  12. Emery, J. P. et al. in Asteroids IV (eds Michel, P. et al.) 203–220 (Univ. Arizona Press, 2016)

  13. Minor Planet Center. Minor Planet Circular Supplement 567918 (3 February 2015)

  14. Minor Planet Center. Minor Planet Circular Supplement 752300 (18 December 2016)

  15. Jet Propulsion Laboratory. Horizons Small-Body Database (retrieved 20 December 2016)

  16. Grav, T. et al. WISE/NEOWISE observations of the Jovian Trojans: preliminary results. Astrophys. J. 742, 40 (2011)

    Article  ADS  Google Scholar 

  17. Denneau, L. et al. The Pan-STARRS moving object processing system. Publ. Astron. Soc. Pacif. 125, 357–395 (2013)

    Article  ADS  Google Scholar 

  18. Luu, J. & Jewitt, D. Cometary activity of 2060 Chiron. Astron. J. 100, 913–932 (1990)

    Article  ADS  Google Scholar 

  19. Milani, A. et al. The OrbFit Software Package (GNU General Public License, accessed 8 January 2015)

  20. Chesley, S. R. & Milani, A. NEODyS: an online information system for near-Earth objects. Bull. Am. Astron. Soc. 31, abstr. 28.06 (1999)

    Google Scholar 

  21. Standish, E. M. Planetary and Lunar Ephemerides DE405/LE405. Interoffice Memorandum 10m 312.F-98-048 (NASA Jet Propulsion Laboratory, 1998)

  22. Wisdom, J. & Holman, M. Symplectic maps for the n-body problem: stability analysis. Astron. J. 104, 2022–2029 (1992)

    Article  ADS  Google Scholar 

  23. Chambers, J. E. A hybrid symplectic integrator that permits close encounters between massive bodies. Mon. Not. R. Astron. Soc. 304, 793–799 (1999)

    Article  ADS  Google Scholar 

  24. Chambers, J. E & Migliorini, F. MERCURY - a new software package for orbital integrations. AAS/Division of Planetary Sciences meeting 29, abstr. 27.06 (1997)

    ADS  Google Scholar 

Download references


We acknowledge the use of the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the USA, Italy and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona Board of Regents; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, The Leibniz Institute for Astrophysics Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia. This work made use of data and/or services provided by the International Astronomical Union’s Minor Planet Center. This work was supported in part by the Natural Sciences and Engineering Council (NSERC) of Canada.

Author information

Authors and Affiliations



P.W. and M.C. contributed numerical simulation and orbital analysis. C.V. contributed telescopic observations, and initial orbit determination and uncertainty analysis. All authors contributed equally to this work.

Corresponding author

Correspondence to Paul Wiegert.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Additional information

Reviewer Information Nature thanks D. Yeomans and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

An animation of the motion of asteroid 2015 BZ509

The sizes of Jupiter and the asteroid are exaggerated for clarity but the relative motion around the Sun is correct. The dotted path indicates the trajectory of the asteroid as seen in a frame which co-rotates with the planet (e.g. as in Figure 1). (MP4 12497 kb)

PowerPoint slides

Source data

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Wiegert, P., Connors, M. & Veillet, C. A retrograde co-orbital asteroid of Jupiter. Nature 543, 687–689 (2017).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing