Astron. Astrophys. 346, L65-L68 (1999)

Letter to the Editor

Close approaches of asteroid 1999 AN₁₀: resonant and non-resonant returns

Andrea Milani ¹, Steven R. Chesley ¹ and Giovanni B. Valsecchi <sup>2

1</sup> Dipartimento di Matematica, Università di Pisa, Via Buonarroti 2, I-56127 Pisa, Italy (milani@dm.unipi.it, chesley@dm.unipi.it)
² IAS-Planetologia, Area di ricerca CNR, Via Fosso del Cavaliere, I-00133 Roma, Italy (giovanni@ias.rm.cnr.it)

Received 13 April 1999 / Accepted 14 May 1999

Abstract

The Earth passes very close to the orbit of the asteroid 1999 AN₁₀ twice per year, but whether or not this asteroid can have a close approach depends upon the timing of its passage across the ecliptic plane. Among the possible orbits there are some with a close approach in 2027. The period of the asteroid may be perturbed in such a way that it returns to an approach to the Earth at either of the possible encounter points. We have developed a theory which successfully predicts the 25 possible such returns up to 2040. We have also identified 6 more close approaches resulting from the cascade of successive returns. Because of this extremely chaotic behaviour there is no way to predict all possible approaches for more than a few decades after any close encounter, but the orbit will remain dangerously close to the orbit of the Earth for about 600 years.

Key words: minor planets, asteroids chaos

This article contains no SIMBAD objects.

Contents

• 1. The 2027 encounter with 1999 AN₁₀
• 2. Resonant and non-resonant returns
• 3. Global return analysis
• 4. In the long run
• References

© European Southern Observatory (ESO) 1999

Online publication: June 17, 1999
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