As a result, from 1979 through the beginning of 1999, Pluto is closer to the sun than Neptune. Like many asteroids, Pluto's orbit is tilted with respect to the planets, which orbit the sun along the same plane, called the ecliptic. It is as if they are marbles rolling around on a plate. Pluto rolls on a plate slightly tilted with respect to the ecliptic. But Pluto is shaped like a ball, you say, and most asteroids are irregularly shaped.
Shape is mostly a function of size.
When they coalesced out of the flat swirling cloud of dust and gas that formed our solar system, smaller bodies tended to be irregularly shaped and larger ones, because of their mass, tended to contract evenly into balls. The surface is distinctly mottled, a mixture of methane and other ices with what look like rocky outcroppings. Pluto is thus a rocky iceball, and we have seen its like before. Pluto looks like a comet. Most of the cometary bodies orbit in a band of material many times farther from the sun than the farthest planet, a place in space called the Oort Cloud.