The 12 signs of the zodiac as we know them today evolved over several thousand years. Since each sign has a ruling planet, early astrologers made associations between the five planets they viewed with the naked eye and what occurred here on earth.
The discovery of each new planet seemed to mark a major step in the evolution of humanity. The planet Uranus was discovered in 1781 which coincided with the start of the Industrial Revolution. There was much upheaval during this time with the American War of Independence (1775–1783) and the events leading up to the beginning of the French Revolution. Uranus which rules the sign of Aquarius is associated with the keywords rebellion, upheaval, and independence.
Pluto which is Scorpio’s planetary ruler was discovered during the rise of fascism which led to the Second World War. Its discovery as a planet also coincides with the advent of organized crime and the Great Depression of the 1930s. Astrological keywords used to describe Pluto are underground, elimination and seduction.