Pluto was discovered in 1930 and named by an 11 year old girl named Venetia Burney. Until 2006, Pluto was considered the 9th planet from the sun (although this isn’t always the case as its rotation sometimes brings it closer to the sun than Neptune). In 2006, however, astronomers reclassified Pluto as a dwarf planet. This doesn’t stop most astrologers from continuing to view Pluto as the ruling planet of Scorpio.
In astrology, Pluto represents destruction to make way for renewal. Pluto supports bringing something into the light, whether it be literal, as in mining and archaeology, or figurative as in detective work or research.