2004 XR190 y (145452) 2005 RN43 have unusual
orbits because, in spite of its low excentrity (almost circular orbits),
they have high inclination over the ecliptic plane.
In
celestial mechanics, the Kozai mechanism, or the Lidov–Kozai
mechanism, causes a periodic exchange between the inclination and
eccentricity of an orbit. The effect was described in 1961 by the
Soviet specialist in space dynamics Michael Lidov while analysing the
orbits of artificial and natural satellites of planets, and in 1962 by
the Japanese astronomer Yoshihide Kozai while analyzing the orbits of
the asteroids. Since then this effect has been found to be an important
factor shaping the orbits of irregular satellites of the planets,
trans-Neptunian objects, and a few extrasolar planets and multiple star
systems. (Wikipedia)
