Pluto

The dwarf planet Pluto orbits the Sun beyond Neptune on a relatively elongated orbit with a strong inclination away from the plane in which the other planets are orbiting the Sun. Since part of Pluto's orbit lies inside the orbit of Neptune, Pluto is sometimes closer to the Sun than Neptune.



With a diameter of 2,374 kilometers Pluto is smaller than the Earth's Moon. The center of Pluto is a solid rocky core with metal impurities that may surround an ocean of liquid water. Above it a mantle is located, made of water ice and bland crust composed mostly of nitrogen ice blended with water ice, methane and carbon monoxide.



Pluto's surface is covered with a wide range of different structures. A smooth ice plains can be found in the neighborhood of high mountains, broken ice floes, windblown dunes or traces of impact craters. Above the surface there is a thin atmosphere of thickness up to 150 kilometers containing substances released from the surface, namely nitrogen.



The orange-brown hues in some parts of Pluto's surface are caused probably by substances formed from organic compounds present in the atmosphere or crust of Pluto with the help of the Sun's ultraviolet radiation. There are even indications that Pluto may not be a geologically dead body, but it is in this direction still active.