Gemini

Gemini

Constellation
List of stars in Gemini
Abbreviation	Gem
Genitive	Geminorum
Pronunciation	/ˈdʒɛmɨnaɪ/, genitive /ˌdʒɛmɨˈnɒrəm/
Symbolism	the Twins, Castor & Pollux
Right ascension	7
Declination	+20
Area	514 sq. deg. (30th)
Main stars	8, 17
Bayer/Flamsteed stars	80
Stars with known planets	3
Bright stars	4
Nearby stars	1
Brightest star	Pollux (β Gem) (1.1m)
Nearest star	GJ 251 (18.2 ly)
Messier objects	1
Meteor showers	Geminids Rho Geminids
Bordering constellations	Lynx Auriga Taurus Orion Monoceros Canis Minor Cancer
Visible at latitudes between +90° and −60°. Best visible at 21:00 (9 p.m.) during the month of February.

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 (Unicode ♊). 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 Urania's Mirror, 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.^{[citation needed]} 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.^{[citation needed]} 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.^{[original research?]}

Astrology

As of 2008^[update], 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

• Messier 35 open cluster
• Geminga, Gemini gamma-ray source

References

• H. A. Rey, The Stars — A New Way To See Them. Enlarged World-Wide Edition. Houghton Mifflin, Boston, 1997. ISBN 0-395-24830-2.
• Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0007251209. Princeton University Press, Princeton. ISBN 978-0691135564.

External links

Wikimedia Commons has media related to: Gemini

• The Deep Photographic Guide to the Constellations: Gemini
• The clickable Gemini
• wikisky.org: Gemini constellation
• Star Tales – Gemini

Coordinates: 07^h 00^m 00^s, +20° 00′ 00″