Editing 2002 AA29 (section)

=== Orbital data ===
Shortly after the discovery by LINEAR, Scientists at the [[Jet Propulsion Laboratory]] (JPL), the [[Athabasca University]] ([[Canada]]), the [[Queen's University at Kingston|Queen's University]] in [[Kingston, Ontario|Kingston (Ontario, Canada)]], the [[York University]] in [[Toronto]] and the [[Tuorla Observatory]] of the [[University of Turku]] in [[Finland]] determined the unusual orbit of {{mp|2002 AA|29}}, and through further observations at the [[Canada–France–Hawaii Telescope]] in Hawaii it was confirmed that:

[[image:2002aa29-orbit-3.png|thumb|Orbits of {{mp|2002 AA|29}} and Earth about the Sun, looking down on the ecliptic plane from above the Sun's North Pole; Image: [[Jet Propulsion Laboratory|JPL]]]]
* Its orbit lies for the most part inside Earth's orbit. The orbits of most asteroids lie in the [[asteroid belt]] between [[Mars]] and [[Jupiter]]. Through orbital disturbances by the gas giant planets, mainly Jupiter and the [[Kirkwood gap]]s, and through the [[Yarkovsky effect]] (force due to asymmetrical absorption and emission of infrared radiation) asteroids are diverted into the inner [[Solar System]], where their orbits are further influenced by close approaches with the inner planets. {{mp|2002 AA|29}} has probably been brought in the same way from the outer Solar System into Earth's influence. However, it is also suggested that the asteroid has always been on a near-Earth orbit and thus that it or a precursor body was formed near Earth's orbit. In this case one possibility is that it could be a fragment from a collision of a middle-sized asteroid with Earth or the [[Moon]].<ref name="lpsc2004">M. Connors, C. Veillet, R. Brasser, P. Wiegert, P. W. Chodas, S. Mikkola, K. Innanen: ''[http://www.lpi.usra.edu/meetings/lpsc2004/pdf/1565.pdf Horseshoe Asteroids and Quasi-satellites in Earth-like Orbits.]'' in: ''35th Lunar and Planetary Science Conference, 15.–19. März 2004.'' League City Texas 2004, 3., Abstract Nr. 1565 (PDF).</ref>
* Its mean orbital period is one [[sidereal year]]. After it was diverted into the inner Solar System – or formed on a path near Earth's orbit – the asteroid must have been moved into an orbit corresponding with Earth. In this orbit it was repeatedly pulled by Earth in such a way that its own orbital period became the same as that of Earth. In the current orbit, Earth thus holds the asteroid in synchronicity with its own orbit.

[[image:2002aa29-orbit-2.png|thumb|Orbits of {{mp|2002 AA|29}} and Earth about the Sun, seen from the side; Image: [[Jet Propulsion Laboratory|JPL]]]]
* The orbit of the asteroid is almost circular, with an [[orbital eccentricity|eccentricity]] of 0.012 which is even lower than that of the Earth at 0.0167. The other near-Earth asteroids have on average a significantly higher eccentricity of 0.29. Also, all other asteroids in 1:1 resonance with Earth known before 2002 have very strongly elliptical orbits – e.g. the eccentricity of (3753) Cruithne is 0.515. At the time of its discovery the orbit of {{mp|2002 AA|29}} was unique, because of which the asteroid is often called the first true co-orbital companion of Earth, since the paths of previously discovered asteroids are not very similar to Earth's orbit. The very low orbital eccentricity of {{mp|2002 AA|29}} is also an indication that it must always have been on a near-Earth orbit, or the Yarkovsky effect must have comparatively strongly caused it to spiral into the inner Solar System over billions of years, since as a rule asteroids which have been steered by planets have orbits with higher eccentricity.
* The orbital inclination with respect to the [[ecliptic]] (orbital plane of Earth) of {{mp|2002 AA|29}} is a moderate 10.739°. Hence its orbit is slightly tilted compared with that of Earth.