18. PLUTO

PLUTO, discriminated, a bastard, if you want. Is it a planet or not? Not, in fact, by decision at the International Astronomical Conference in August 2006. It has a diameter of only 2300 km, one sixth of the earth diameter, in volume not yet 0,02 part of the earth. The excentricity of the orbit and slope of the plane deviates highly of those of the other planets, the ellipse crosses the ellipses of the other ones. Perhaps just an object from the Kuiperbelt (discussed later) ? Officially it is now a "dwarf-planet".
Pluto has relatively a very large "moon" on a distance of only 20.000 km, therefore he is often indicated as a "double planet".
Distance to earth: 6 x 10^9 km.