Pluto wasn't actually seen until February 18, 1930, by Clyde Tombaugh. The sighting was coincidental with a rise in fascism. Pluto was not named for the god of the underworld, but for a cartoon dog. Really.
The original glyph for Pluto was PL, standing for Percival Lowell, the guy who "discovered" Pluto. (Get it? The initials: P and L, make into the glyph. Cute, huh?) Actually, Lowell merely predicted Pluto's existence and location due to perturbations in the orbits of Uranus and Neptune. As it turns out, though, Pluto is too small to have the effect predicted. Pluto has a cute little moon named Charon.
Pluto takes about 248 years to make a complete cycle through all twelve signs. The period Pluto spends in each sign varies from 12 to 32 years due to the eccentricity of its orbit. Like atomic energy (a force ruled by Pluto), the presence and direction of Pluto's energy is never obvious until used. The sign position of Pluto is interpreted as a characteristic of a generation or historical significance. In your natal chart, Pluto's significance is interpreted from its house position and the aspects it makes with your other natal planets. Pluto represents areas of intense energy and where you want to exercise power or control. Pluto is your friend. Always. Remember that. Hold that thought. Pluto is the co-ruler of Scorpio.