Mercury and Venus in astrology are the only two remaining planets ruling two signs each, Mercury ruling over Gemini and Virgo, and Venus ruling over Taurus and Libra.

When Uranus was discovered in 1781, it was assigned as the primary ruler of Aquarius, leaving Saturn to Capricorn. When Neptune was discovered in 1846, it was assigned to Pisces leaving Jupiter to Sagittarius, and when Pluto was discovered in 1930, it was eventually assigned as the true ruler of Scorpio, leaving Mars to Aries. Eris, discovered in 2005, may be assigned to Libra leaving Venus to Taurus. One more planet needs to be discovered single out the Mercury rulership. Sun always ruled Leo and Moon always ruled Cancer.

When a new planet is discovered, the name given it as well as the era or period it is discovered in are strong clues to the sign it rules. Uranus was discovered in the midst of major world revolutions most notably America's independance from Britain. It also rules science, invention, and modernization. Neptune symbolized gas, oil, steam, film, collective conciousness, and secret societies. Pluto symbolizes World War, resets, and atomic power. Eris may symbolize global unity and interdependance and the final planet may symbolize global communications and ecological restoration. These three new influences continue to unfold or gain power with time.

Personally I believe Venus is the primary or true ruler Taurus and Eris Libra, but both do have some of the other's influence. Mercury is much harder for me to figure out appearing to have an equal amount of both Gemini and Virgo.

Some of the strongest indications of unfolding rulerships are the birth of new nations and the dominance of certain political leaders. Uranus, for example, coincided with the discovery or establishment of the Americas, and especially the United States. Neptune with the Oceans, Pluto with Russia, and Eris/Xena with the rise of China. The two most powerful leaders today are Donald Trump(Gemini), and Vladimir Putin(Libra). Both these air signs are linked to the Mercury/Venus rulership puzzle and their unfoldment.

Personally, I think the next two signs to become associated with two new planets are Eris/Libra and X/Gemini, in that order. Eris/Libra will unite the world, with the Taurus side involving more land/resources. x/Gemini will will reeducate the world, with the Virgo side restoring global health and ecology. charts.