Expressive and quick-witted, Gemini represents two different personalities in one and you will never be sure which one you will face. They are sociable, communicative and ready for fun, with a tendency to suddenly get serious, thoughtful and restless. Gemini is the third astrological sign in the zodiac, originating from the constellation of Gemini. Under the tropical zodiac, the sun transits this sign between May 21 and June 21. Gemini is represented by The Twins Castor and Pollux.