Gemini, the third sign of the zodiac, rules the sky from around May 21st to June 20th. The dynamism and intelligence of this Air sign are derived from Mercury, the planet that rules it. Mercury, the lightning-fast emissary of the Roman gods, rules not only the physical mediums of speech, writing, and listening, but also the mental and intellectual domains, including learning, logic, and travel (both actual and imagined). Because of this strong impact, Geminis acquire their signature eloquence, mental agility, and voracious appetite for learning and adventure.