Abstract
Near-Earth asteroids range in size from a few metres to more than 30 km: in addition to playing an important role in past and present impact rates on the Earth, they might one day be exploited as bases for space exploration or as mineral resources. Many near-Earth asteroids move on orbits crossing that of the Earth, but none has hitherto been identified as a dynamical companion to the Earth. Here we show that the orbit of asteroid 3753 (1986 TO), when viewed in the reference frame centred on the Sun but orbiting with the Earth, has a distinctive shape characteristic of ‘horseshoe’ orbits. Although horseshoe orbits are a well-known feature of the gravitational three-body problem1, the only other examples of objects moving on such orbits are the saturnian satellites Janus and Epimetheus2—and their behaviour is much less intricate than that of 3753. Moreover, the fact that 3753 exhibits such a dynamical relationship with the Earth shows that, although it is not a satellite of our planet per se, it is, apart from the Moon, the only known natural companion of the Earth.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Szebehely, V. Theory of Orbits (Academic, New York, 1967).
Dermott, S. F. & Murray, C. D. The dynamics of tadpole and horseshoe orbits. II The coorbital satellites of Saturn. Icarus 48, 12–22 (1981).
Minor Planet Circular 11312 (Minor Planet Center, Smithsonian Astrophys. Observ., Cambridge, MA, 1986).
IAU Circ. No. 4262 and 4266 (1986)
Bowell, E. The Asteroid Orbital Elements Databaseavailable at ftp://ftp.lowell.edu/pub/elgb/astorb.html(1997).
Bowell, E.et al. in Asteroids II (eds Binzel, R. P. et al.) 524–556 (Univ. Arizona Press, Tucson, 1989).
Rabinowitz, D. L. The size distribution of earth-approaching asteroids. Astrophys. J. 407, 412–427 (1993).
Wisdom, J. & Holman, M. Symplectic maps for the n-body problem. Astron. J. 102, 2022–2029 (1991).
Acknowledgements
We thank M. Holman for the use of his integration codes. This work was supported in part by the Natural Sciences and Engineering Research Council of Canada.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Wiegert, P., Innanen, K. & Mikkola, S. An asteroidal companion to the Earth. Nature 387, 685–686 (1997). https://doi.org/10.1038/42662
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/42662
This article is cited by
-
Orbital stability analysis and photometric characterization of the second Earth Trojan asteroid 2020 XL5
Nature Communications (2022)
-
From horseshoe to quasi-satellite and back again: the curious dynamics of Earth co-orbital asteroid 2015 SO2
Astrophysics and Space Science (2016)
-
A trio of horseshoes: past, present and future dynamical evolution of Earth co-orbital asteroids 2015 XX 169 $\mbox{XX}_{169}$ , 2015 YA and 2015 YQ 1 $\mbox{YQ}_{1}$
Astrophysics and Space Science (2016)
-
Earth’s Trojan asteroid
Nature (2011)
Comments
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.
