Gemini (Gem-en-i.e.) (♊) is the third of the astrological signs in the Zodiac, originating from the constellation of Gemini. In astrology, Gemini is considered a “masculine”, positive (extrovert) sign. Perhaps the most dominant Geminian characteristic is versatility. It is also considered an air sign, and is one of four mutable signs. Gemini has been closely associated with the planet Mercury and is considered to be ruled by it. Being the third sign of the zodiac, Gemini has been associated with the astrological third house.
Individuals born when the Sun was in this sign are considered Gemini individuals. Under the tropical (Western) zodiac, Sun is in the sign of Gemini roughly from May 20 to June 21, ending at the moment of summer solstice by definition. In western astrology, this sign is no longer aligned with the constellation as a result of the precession of the equinoxes. Under the sidereal zodiac, it is currently there roughly from June 15 to July 15. The Sanskrit name of Gemini in Hindu astrology is Mithuna.
Zodiac Symbol: Twins
Duration (Tropical, Western): 21 May – 21 June (2011, UTC)
Duration (Sidereal, Hindu): 14 June – 31 July (2011, UTC)
Zodiac Element: Air
Zodiac Quality: Mutable
Detriment: Jupiter, Neptune
Exaltation: North Node
Fall: South Node
Gemini were the twin brothers Castor and Pollux in Greek mythology, also sometimes known as Iabal and Ivbal. They were the sons of Leda by Tyndareus and Zeus respectively. They were also the brothers of Helen of Troy and Clytemnestra. They are known collectively in Greek as the Dioscuri (Greek: Διόσκουροι, Dioskouroi) “sons of Zeus.” Loki, the trickster figure from Norse mythology, is often associated with Gemini and its ruling planet Mercury.
Generally, the natives of Gemini are considered to be compatible with the natives of the other air signs, Libra and Aquarius, and the natives of the fire signs, Aries, Leo and Sagittarius. Virgo and Pisces are signs of the other nature (feminine/introverted), but are considered semi-compatible with Gemini due to them having the same mutable quality.
There are many variables in the astrology chart that determine compatibility of individuals. The position of the Sun, the Moon, the planets and the aspects they form with each other are assessed by astrologers before judgment on compatibility is made. The signs listed as compatible with Gemini do not reflect an individual profile or individual reading as interpreted within astrology, but rather reflect a general guideline and reference to compatibility as dictated by variables such as Qualities and Elements within the Zodiac. The branch of astrology dealing with interpersonal compatibilities is called Synastry.
Definition courtesy Wikipedia.