Gemini (the twins) is one of the constellations of the zodiac. It is part of the winter sky, between Taurus to the west and the dim Cancer to the east, with Auriga and the near-invisible Lynx to the north and Monoceros and Canis Minor to the south. The Gemini program is named for it. Gemini includes two bright stars, named after the two twins, who correspond to the Dioscuri in Greek mythology - Castor (a), a pretty telescopic binary (actually sextuple), and Pollux (ß), which is brighter and more southwesterly.
This constellation is identified with the Dioscuri, Castor, and Pollux (or Polydeuces), for whom its brightest stars are also named. The astrological sign Gemini (May 21 - June 20) is associated with the constellation. In some cosmologies, Gemini is associated with the classical element Air and is thus called an Air Sign (with Libra and Aquarius). Its polar opposite is Sagittarius. Gemini is a Mutable Air sign and is the most mobile sign. Gemini is the third stage in the evolutionary process of the zodiac, where we begin to explore our immediate environment and make sense of it.
The keywords for Gemini are "I THINK."