Gemini (constellation)

  • Carter
  • Taurus
  • Orion
  • Unicorn
  • Small Dog
  • Cancer
  • Lynx

The Twins ( Gemini latin astronomical sign: ♊ ) is a constellation on the ecliptic.


The twins form an elongated rectangle. The striking bright stars Castor ( Castor ) and Pollux are the two northeastern corner points.

Through the eastern part of the twins, the band of the Milky Way moves, so you can find in this area several open clusters.

Since the twins are on the ecliptic, pull the sun, moon and the planets through the constellation. The sun passes through the present twins from 21 June to 21 July. Taking the modern constellation boundaries to reason, the summer period 1989 AD was from 15 BC to 19 October in this constellation.


The twins are among the 48 constellations of the ancient astronomy, which have already been described by Claudius Ptolemy. The constellation is the origin of the zodiac sign Gemini. Due to the precession of Earth's axis, the passage of the sun has over the ancient world but moved.

In 1930, the dwarf planet Pluto was discovered in the evaluation of photographic plates in the twins.


For details, see article: Dioscuri

In Greek mythology, Castor and Pollux were (Lat. Pollux ) inseparable twin brothers. Her mother, Leda, Kastor received from her husband, King Tyndareus of Sparta and Pollux by Zeus, who approached her in the form of a swan. Therefore, Kastor was human and mortal, Pollux, however, of divine origin and immortal. The brothers joined Jason and the Argonauts in their quest for the Golden Fleece and experienced many adventures. In a dispute with their companions, the twin brothers Lynceus and Idas Pollux emerged as the sole survivor. He turned to his divine father and asked him to be able to share his own immortality with Castor. From then on, the brothers spent alternate days in Hades or on Mount Olympus. They were also immortalized as a constellation in the sky.

The Arabs saw the constellation as a reclining lion.

Celestial objects


Pollux ( β Geminorum ), the brightest star in Gemini, is 34 light years away. He is a bright orange giant star of spectral type K0.

γ Geminorum is a 105 light-years distant, white shining star of spectral type A0. The names Alhena or Almeisan are ancient Arabic origin and means something like " fire sign" or " the apparent end."

ε Geminorum is strikingly bright, despite its distance of about 900 light years, it is a giant star of spectral type G5 with 150 times diameter of our sun. The Arabic name Mebsuta derives from " the outstretched paw of the lion " from. The star lies almost exactly on the ecliptic, so it is sometimes covered planet. In 1976, the Mars from Earth drew seen over right in front of the star.

The 60 light years distant star δ Geminorum is also very close to the ecliptic. In 1857 he was covered by Saturn. The Arabic name Wasat means "the center."

Double stars

Castor ( α Geminorum ) is a complex multi- system, in which three main stars orbit around a common center of gravity. Each of the main star is in turn surrounded by a faint companion who is not in the telescope, however, and is only visible spectroscopy. The three main stars can already be observed with a small telescope.

Variable Stars

μ Geminorum is a variable star whose brightness changes with no discernible regularity. It is a deep red shining star of spectral type M0. The name Tejat Posterior means of the " back foot ".

η Geminorum is a red giant in 190 light years away, its brightness varies with a period of about 235 days. He is a semi- regular variables (type SRc ). In addition, he is an eclipsing variable star, because he is surrounded by a faint companion about every three days partially covered him.

ζ Geminorum is a 1200 light years distant variable star of type Delta Cepheids. The Arabic name Mekbuda derives from " the retracted paw of the lion " from.

Messier and NGC objects

The Messier object M35 is an open star cluster in about 3,000 light- years away. He can be seen with the naked eye as a misty patch. With a prism binoculars it can be resolved into individual stars. At higher magnification in the telescope, more and more single stars (totaling about 200 ) are visible.

NGC 2129 is an open cluster in 6,000 light-years, however, contains only a few stars.

In the vicinity of the star δ Geminorum can be found NGC 2392, a planetary nebula in 2,500 light-years away. This refers to a star that has shed its outer shell of gas at the end of its development. What remains is a white dwarf star. In a telescope NGC 2392 appears as a misty round spot. On long exposure photographs structures become visible, reminiscent of a face, which is framed by a fur hood. Therefore, the object was called the Eskimo nebula.