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.

Retrograde spins of near-Earth asteroids from the Yarkovsky effect


Dynamical resonances in the asteroid belt are the gateway for the production of near-Earth asteroids1 (NEAs). To generate the observed number of NEAs, however, requires the injection of many asteroids into those resonant regions. Collisional processes have long been claimed as a possible source1,2,3, but difficulties with that idea have led to the suggestion that orbital drift arising from the Yarkovsky effect4,5,6,7 dominates the injection process8,9,10. (The Yarkovsky effect is a force arising from differential heating—the ‘afternoon’ side of an asteroid is warmer than the ‘morning’ side.) The two models predict different rotational properties of NEAs: the usual collisional theories2 are consistent with a nearly isotropic distribution of rotation vectors, whereas the ‘Yarkovsky model’ predicts an excess of retrograde rotations. Here we report that the spin vectors of NEAs show a strong and statistically significant excess of retrograde rotations, quantitatively consistent with the theoretical expectations of the Yarkovsky model.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Latitude distributions for main belt asteroids and NEAs.


  1. 1

    Greenberg, R. & Nolan, M. C. in Asteroids II (eds Binzel, R. P. et al. ) 778–804 (Arizona Univ. Press, Tucson, 1989)

    Google Scholar 

  2. 2

    Davis, D. R., Weidenschilling, S. J., Farinella, P., Paolicchi, P. & Binzel, R. P. in Asteroids II (eds Binzel, R. P. et al.) 805–826 (Arizona Univ. Press, Tucson, 1989)

    Google Scholar 

  3. 3

    Zappalà, V., Cellino, A., Di Martino, M., Migliorini, F. & Paolicchi, P. Maria's family: physical structure and possible implications for the origin of giant NEAs. Icarus 129, 1–20 (1997)

    ADS  Article  Google Scholar 

  4. 4

    Vokrouhlicky, D. Diurnal Yarkovsky effect as a source of mobility of meter-sized asteroidal fragments. I. Linear theory. Astron. Astrophys. 335, 1093–1100 (1998)

    ADS  Google Scholar 

  5. 5

    Vokrouhlicky, D. A complete linear model for the Yarkovsky thermal force on spherical asteroid fragments. Astron. Astrophys. 344, 362–366 (1999)

    ADS  Google Scholar 

  6. 6

    Vokrouhlicky, D. & Farinella, P. The Yarkovsky seasonal effect on asteroidal fragments: A nonlinearized theory for the plane-parallel case. Astron. J. 116, 2032–2041 (1998)

    ADS  Article  Google Scholar 

  7. 7

    Spitale, J. & Greenberg, R. Numerical evaluation of the general Yarkovsky effect: Effects on semimajor axis. Icarus 149, 222–234 (2001)

    ADS  Article  Google Scholar 

  8. 8

    Bottke, W. F., Jedicke, R., Morbidelli, A., Petit, J. & Gladman, B. Understanding the distribution of near-Earth asteroids. Science 288, 2190–2194 (2000)

    ADS  CAS  Article  Google Scholar 

  9. 9

    Bottke, W. F. et al. Debiased orbital and absolute magnitude distribution of the near-Earth objects. Icarus 156, 399–433 (2002)

    ADS  Article  Google Scholar 

  10. 10

    Morbidelli, A. & Vokrouhlicky, D. The Yarkovsky-driven origin of near-Earth asteroids. Icarus 163, 120–134 (2003)

    ADS  Article  Google Scholar 

  11. 11

    Pravec, P., Harris, A. W. & Michalowski, T. in Asteroids III (eds Bottke, W. F. Jr et al.) 113–122 (Arizona Univ. Press, Tucson, 2002)

    Google Scholar 

  12. 12

    Kryszczyńska, A. Database of Asteroid Spin Vectors Determinations. 〈〉 accessed 23 October 2003.

  13. 13

    Kaasalainen, M. et al. Photometry and models of eight near-Earth asteroids. Icarus 167, 178–196 (2004)

    ADS  Article  Google Scholar 

  14. 14

    Magnusson, P. et al. in Asteroids II (eds Binzel, R. P. et al.) 66–97 (Arizona Univ. Press, Tucson, 1989)

    Google Scholar 

  15. 15

    Rubincam, D. P. Radiative spin-up and spin-down of small asteroids. Icarus 148, 2–11 (2000)

    ADS  Article  Google Scholar 

  16. 16

    Vokrouhlicky, D., Nesvorny, D. & Bottke, W. F. The vector alignments of asteroid spins by thermal torques. Nature 425, 147–151 (2003)

    ADS  CAS  Article  Google Scholar 

  17. 17

    Cellino, A., Bus, S. J., Doressoundiram, A. & Lazzaro, D. in Asteroids III (eds Bottke, W. F. Jr et al.) 633–643 (Arizona Univ. Press, Tucson, 2002)

    Google Scholar 

Download references


This work was supported by MIUR (Italy), KBN (Poland) and the Academy of Sciences (Czech Republic). We thank D. Vokrouhlicky and S. Shore for comments and suggestions.

Author information



Corresponding author

Correspondence to P. Paolicchi.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

La Spina, A., Paolicchi, P., Kryszczyńska, A. et al. Retrograde spins of near-Earth asteroids from the Yarkovsky effect. Nature 428, 400–401 (2004).

Download citation

Further reading


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