Gemini

For information on the US space program named Gemini see Gemini program.

Gemini (the twins) is one of the constellations of the zodiac. It is part of the winter sky, lying 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.

Notable features

Gemini includes two bright stars, named after the two twins, who correspond to the Dioscuri in Greek mythology - Castor (α), a pretty telescopic binary (actually sextuple), and Pollux (β), which is brighter and more southwesterly. The other stars are relatively dim - only one, Alhena (γ) is ever seen from a large city - and trace out a rectangle to the southeast.

The planet Pluto was discovered in this constellation in 1930, near the star Wasat (δ Geminorum).

Notable deep sky objects

The brightest deep sky object of Gemini is M35, an open cluster of 5th magnitude, 2 800 light-years from earth. It is northwest of η Geminorum, near the western edge of the constellation.

Mythology

This constellation is identified with the Dioscuri, Castor and Pollux (or Polydeuces), for whom its brightest stars are also named. These twin brothers were the brothers of Helen of Troy and Clytemnestra, by Leda.

Astrology

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 thus called an Air Sign (with Libra and Aquarius). Its polar opposite is Sagittarius.