|"Here's the tiny Pluto. Many think this planet used to be an asteroid that fell into an orbit around the Sun, or that it was a moon of one of the gas giants that broke off and began to orbit the Sun. Little is known about this cold, small world. But maybe, someday we'll go there!"
Most of the time, Pluto is the farthest planet from the Sun. It's the last stop in the solar system before interstellar Space. In Roman mythology, Pluto (Greek: Hades) is the god of the underworld. The planet received this name perhaps because it's so far from the Sun that it is in perpetual darkness.
Pluto was discovered in 1930 when calculations predicted a planet beyond Neptune, based on the motions of Uranus and Neptune. Not knowing of the calculations, Clyde W. Tombaugh at Lowell Observatory in Arizona did a very careful sky survey which turned up Pluto anyway.
Pluto is so small and unlike a planet that there are some who think it should be better classified as a large asteroid or comet. Some consider it to be the largest of the Oort/Cloud/Kuiper Belt objects. Historically Pluto has been classified as a planet and it is likely to remain so.