Gemini (constellation)

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

In mythology, the Gemini are Castor and Polydeuces.

Gemini

Constellation
List of stars in Gemini
Abbreviation	Gem
Genitive	Geminorum
Right ascension	7
Declination	20
Area	514 sq. deg. (30th)
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 (, and Latin for 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

Since this constellation is easily viewable as two parallel stick figures [1], considering faint stars visible to the naked eye, it was associated with the myth of Castor and Polydeuces (also known as the Dioscuri). The myth of these twins heavily concerns cattle theft, and may be connected to early views of the Milky Way, as a herd of dairy cows or cattle, by which they are situated.

The orientation of the constellation can vary (since they readily form stick figures whether leaning right or left), though the twins are usually viewed as left leaning. However, when right leaning, one of the twins resides 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. In this situation, together with the area of the sky that is deserted (now considered as the new and extremely faint constellations Camelopardalis and Lynx), and 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 Herakles.

Astrology

The Western astrological sign Gemini of the tropical zodiac (May 21 - June 20) differs from the astronomical constellation and the Hindu astrological sign of the sidereal zodiac (June 20 - July 20).

In some cosmologies, Gemini is associated with the classical element Air, and thus called an Air Sign (with Libra and Aquarius). It is also one of the four mutable signs (along with Virgo, Sagittarius, and Pisces). Its polar opposite is Sagittarius. It is the domicile of Mercury. Each astrological sign is assigned a part of the body, viewed as the seat of its power. Gemini rules the hands and arms. The symbol for Gemini is the twins.

Gemini

Stars with proper names:

• Castor (66/α Gem) – sextuple 1.98, 2.88

• Pollux (78/β Gem) 1.16

• Alhena or Almeisan (24/γ Gem) 1.93

  < ? al-han'ah The brand (on the neck of a camel)

  < ? al-maisan The shining one

• Wasat [Wesat] (55/δ Gem) 3.50

  < وسط السما wasaţ as-samā Middle of the sky

• Mebsuta [Melucta, Meboula] (27/ε Gem) 3.06

  < المبسوطة al-mabsūţa[h] The outstretched (paw of Leo)

• Mekbuda (43/ζ Gem) 4.01

  < المقبوضة al-maqbūđ̧a[h] The pulled in (paw)

• Propus [Praepes] or Tejat Prior (7/η Gem) 3.31

  < πρόπους The fore foot

• 60/ι Gem (or Propus, see η Gem) 3.78
• Tejat Posterior or Nuhatai or Calx or Pish Pai (13/μ Gem) 2.87

• Alzirr (31/ξ Gem) 3.35

  < الزر az-zarr/az-zir

• 1 Gem (or Propus, see η Gem) 4.16

Stars with Bayer designations:

34/θ Gem 3.60; 77/κ Gem 3.57; 54/λ Gem 3.58; 18/ν Gem 4.13; 71/ο Gem 4.89; 80/π Gem 5.14; 62/ρ Gem 4.16; 75/σ Gem 4.23; 46/τ Gem 4.41; 69/υ Gem 4.06; χ Gem 4.94; 83/φ Gem 4.97; 42/ω Gem 5.20; 65/b Gem 5.01; 76/c Gem 5.30; 36/d Gem 5.28; 38/e Gem 4.73; 74/f Gem 5.04; 81/g Gem 4.89; 57/A Gem 5.04

Stars with Flamsteed designations:

2 Gem 6.67; 3 Gem 5.75; 4 Gem 6.88; 5 Gem 5.83; 6/BU Gem 6.51; 8 Gem 6.09; 9 Gem 6.24; 10 Gem 6.58; 11 Gem 6.91; 12 Gem 6.95; 15 Gem 6.54; 15 Gem 9.21; 16 Gem 6.22; 19 Gem 6.38; 20 Gem 6.26; 23 Gem 6.73; 25 Gem 6.45; 26 Gem 5.20; 28 Gem 5.42; 30 Gem 4.49; 32 Gem 6.47; 33 Gem 5.87; 35 Gem 5.68; 37 Gem 5.74 – nearby; 39 Gem 6.20; 40 Gem 6.40; 41 Gem 5.73; 44 Gem 6.00; 45 Gem 5.47; 47 Gem 5.75; 48 Gem 5.85; 49 Gem 7.06; 51 Gem 5.07; 52 Gem 5.84; 53 Gem 5.75; 56 Gem 5.09; 58 Gem 6.17; 59 Gem 5.77; 61 Gem 5.94; 63 Gem 5.20; 64 Gem 5.07; 68 Gem 5.27; 70 Gem 5.58; 79 Gem 6.53; 82 Gem 6.18; 85 Gem 5.38

External links

The Deep Photographic Guide to the Constellations: Gemini