Pluto was discovered, named a planet, then stripped of its planet status long before it ever made one trip around the sun
For being the smallest "planet" in our solar system, Pluto has raised quite the controversy. Despite it's tiny size, it is the tenth-most-massive body that orbits our sun and the second-largest known dwarf planet after Eris. From the time it was discovered to moment it lost it's classification as a planet, it didn't even complete one revolution around the sun.
On February 18, 1930, Clyde Tombaugh discovered a possible moving object after nearly a year of searching. He did this by taking images of the night sky taken two weeks apart and then examine them for differences. The photos taken on January 23 and 29 of 1930, combined with a low-quality photo from January 21 confirmed the movement of the distant planet.
The Lowell Observatory reserved the right to name the new object and received over 1,000 suggestions from all over the world. The name Pluto came from the god of the underworld, which was proposed by an 11-year-old schoolgirl in Oxford, England.
Pluto's orbital period is 248 Earth years, with a chaotic, highly inclined orbit that differs from the rest of the planet. A single day on Pluto, or the time it takes to complete a rotation, is 6.39 Earth days, rotating at an axial tilt of 120-degrees.