Its orbital path doesn't lie in the same plane as the eight planets, but is inclined at an angle of 17°. Its orbit is also more oval-shaped, or elliptical, than those of the planets. That means that sometimes Pluto is a lot nearer to the Sun than at other times, At times Pluto's orbit brings it closer to the Sun than Neptune. read more
Besides: Pluto is small, very small, especially as compared to Jupiter, Saturn,Uranus and Neptune. Pluto is not a gas-planet (as the ones mentioned) It has an orbit that is both very eccentric, and tilts 17 degrees to the orbit of all other planets. read more
Its orbit is also more oval-shaped, or elliptical, than those of the planets. That means that sometimes Pluto is a lot nearer to the Sun than at other times, At times Pluto's orbit brings it closer to the Sun than Neptune. read more