Gemini is one of the
constellations of the
zodiac. Its name is
Latin for "
twins", and it is associated with the twins
Castor and Pollux in
Greek mythology. Its symbol is
(). It lies between
Taurus to the west and the dim
Cancer to the east, with
Auriga and
Lynx to the north and
Monoceros and
Canis Minor to the south.
Notable features
Gemini includes the
open cluster M35.
NGC 2158 is just southeast of M35. Also of note is the unique
Eskimo Nebula, (also known as the Clownface Nebula) just southeast of the open cluster,
NGC 2420. Far northeast of this cluster lies
NGC 2371, a planetary nebula next to the Gemini twin on the right. Another popular planetary nebula in Gemini lies in the southern tip of the constellation, Abell 21 the
Medusa Nebula.
Visualizations
Gemini as depicted in , a set of constellation cards published in London c.1825.
Diagram of
H.A. Rey's alternative way to connect the stars of the constellation Gemini. A pair of twins are shown holding hands.
Gemini is dominated by
Castor and
Pollux, two bright stars that appear relatively close together, encouraging the mythological link between the constellation and twinship. The twin to the right is
Castor, whose brightest star is
α Geminorum (more commonly called Castor), is of the second magnitude, and represents Castor's head. The twin to the left is
Pollux, whose brightest star is
β Geminorum (more commonly called Pollux), is of the first magnitude, and represents Pollux's head. Furthermore, the other stars can be visualized as two parallel lines descending from the two main stars, making it look like two figures.
H.A. Rey has suggested an alternative to the traditional visualization that connected the stars of Gemini to show a pair of twins holding hands. Pollux's torso is represented by star
υ Geminorum, Pollux's right hand by
ι Geminorum, Pollux's left hand by
κ Geminorum: all three of these stars are of the fourth magnitude. Pollux's pelvis is represented by star
δ Geminorum, Pollux's right knee by
ζ Geminorum, Pollux's right foot by
γ Geminorum, Pollux's left knee by
λ Geminorum, and Pollux's left foot by
ξ Geminorum. Gamma Geminorum is of the second magnitude, while delta and xi Geminorum are of the third magnitude. Castor's torso is represented by the star
τ Geminorum, Castor's left hand by
ι Geminorum (which he shares with Pollux), Castor's right hand by
θ Geminorum: all three of these stars are of the fourth magnitude. Castor's pelvis is represented by the star
ε Geminorum, Castor's left foot by
ν Geminorum, and Castor's right foot by
μ Geminorum and
η Geminorum: ε, μ, and η Geminorum are of the third magnitude.
Mythology
Gemini was associated with the myth of
Castor and Pollux, collectively known as the
Dioscuri. One myth of these twins concerns
cattle theft, and may be connected to early myths that described the
Milky Way as a herd of
dairy cows. On star maps, the twins are usually viewed as leaning away from the Milky Way, but are sometimes depicted with one of the twins residing in the Milky Way, and the other outside it, a situation making it appear that one of the twins is stealing the cattle, and the other is observing. Along with the other features of the area in the
Zodiac sign of Gemini (i.e.
Orion,
Auriga, and
Canis Major), this may be the origin of the myth of the cattle of
Geryon, which forms one of
The Twelve Labours of
Heracles.
Astrology
, the Sun appears in the constellation Gemini from June 20 to July 20. In
tropical astrology, the Sun is considered to be in the sign
Gemini from May 22 to June 23, and in
sidereal astrology, from June 16 to July 15.
See also
