Virgos Ruling planet

what is it.

Mercury

I Read it was Chiron a new planet thanks for clarifying.

Mercury.

But Chiron was advanced as a theory, as well as some undiscovered planet Vulcan, as well as the Earth itself.

Vulcan it suppose to be behind the sun on fire

Traditionally, mercury.
For Aquarius, now is generally seen as Uranus, but old style Saturn. The planets were each two to a sign before other planets were discovered. (with the exception of Leo and Cancer)
Sun: Leo
Moon: Cancer
Mars: Aries Scorpio
Mercury: Virgo Gemini
Venus: Taurus Libra
Saturn: Capricorn Aquarius
Jupiter: Sagittarius Pisces

With each discovery though, signs were assigned to different planets.