The Sun is the centre of our solar system. Astrologically it is the planetary ruler of Leo. It represents the Self, our identity, our sense of individuality. The Sun shows our vitality, creative centre and the core of our conscious self.
Self, vitality, personality, identity. The Sun is how we see ourselves inside, as opposed to how others see us (which is more linked to the Ascendant).
Per 12 Signs
About 1 month.
The Sun never goes retrograde.