Gemini is one of the
constellationIn modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
s of the
zodiacIn astronomy, the zodiac is a circle of twelve 30° divisions of celestial longitude which are centred upon the ecliptic: the apparent path of the Sun across the celestial sphere over the course of the year...
. It was one of the 48 constellations described by the
2nd centuryThe 2nd century is the period from 101 to 200 in accordance with the Julian calendar in the Christian/Common Era. It is considered part of the Classical era, epoch, or historical period...
astronomer
PtolemyClaudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...
and it remains one of the 88 modern constellations today. Its name is
LatinLatin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for "twins", and it is associated with the twins
Castor and PolluxIn Greek and Roman mythology, Castor and Pollux or Polydeuces were twin brothers, together known as the Dioscuri . Their mother was Leda, but Castor was the mortal son of Tyndareus, king of Sparta, and Pollux the divine son of Zeus, who visited Leda in the guise of a swan...
in
Greek mythologyGreek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...
. Its symbol is
.
Location
Gemini lies between
TaurusTaurus is one of the constellations of the zodiac. Its name is a Latin word meaning 'bull', and its astrological symbol is a stylized bull's head:...
to the west and
CancerCancer is one of the twelve constellations of the zodiac. Its name is Latin for crab and it is commonly represented as such. Its symbol is . Cancer is small and its stars are faint...
to the east, with
AurigaAuriga is a constellation in the northern sky. Its name is Latin for 'charioteer' and its stars form a shape that has been associated with the pointed helmet of a charioteer. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains among the 88 modern...
and
LynxLynx is a constellation in the northern sky, introduced in the 17th century by Johannes Hevelius. It is named after the lynx, a genus of cat. It is a very faint constellation; its brightest stars form a zigzag line.-History:...
to the north and
MonocerosMonoceros is a faint constellation on the celestial equator. Its name is Greek for unicorn. Its definition is attributed to the 17th-century Dutch cartographer Petrus Plancius. It is bordered by Orion to the west, Gemini to the north, Canis Major to the south and Hydra to the east...
and
Canis MinorCanis Minor is a small constellation. It was included in the 2nd century astronomer Ptolemy's 48 constellations, and is still included among the 88 modern constellations...
to the south.
The Sun resides in Gemini from 21 June to 21 July each year. By mid August, Gemini will appear along the eastern horizon in the morning sky prior to sunrise. The best time to observe Gemini at night is overhead during the months of January and February. By April and May, the constellation will be visible soon after sunset in the west.
The easiest way to locate the constellation is to find its two brightest stars
CastorCastor is the second brightest star in the constellation Gemini and one of the brightest stars in the night sky. Although it has the Bayer designation "alpha", it is actually fainter than Beta Geminorum...
and
PolluxPollux is an orange giant star approximately 34 light-years from the Earth in the constellation of Gemini . Pollux is the brightest star in the constellation, brighter than Castor...
eastward from the familiar “V” shaped
asterismIn astronomy, an asterism is a pattern of stars recognized on Earth's night sky. It may form part of an official constellation, or be composed of stars from more than one. Like constellations, asterisms are in most cases composed of stars which, while they are visible in the same general direction,...
of
TaurusTaurus is one of the constellations of the zodiac. Its name is a Latin word meaning 'bull', and its astrological symbol is a stylized bull's head:...
and the three stars of
OrionOrion, often referred to as The Hunter, is a prominent constellation located on the celestial equator and visible throughout the world. It is one of the most conspicuous, and most recognizable constellations in the night sky...
’s belt. Another way is to mentally draw a line from the
PleiadesIn astronomy, the Pleiades, or Seven Sisters , is an open star cluster containing middle-aged hot B-type stars located in the constellation of Taurus. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky...
star clusterStar clusters or star clouds are groups of stars. Two types of star clusters can be distinguished: globular clusters are tight groups of hundreds of thousands of very old stars which are gravitationally bound, while open clusters, more loosely clustered groups of stars, generally contain less than...
located in Taurus and the brightest star in
LeoLeo is one of the constellations of the zodiac. Its name is Latin for lion. Its symbol is . Leo lies between dim Cancer to the west and Virgo to the east.-Stars:...
,
RegulusRegulus is the brightest star in the constellation Leo and one of the brightest stars in the night sky, lying approximately 77.5 light years from Earth. Regulus is a multiple star system composed of four stars which are organized into two pairs...
. In doing so, you are drawing an imaginary line that is relatively close to the
eclipticThe ecliptic is the plane of the earth's orbit around the sun. In more accurate terms, it is the intersection of the celestial sphere with the ecliptic plane, which is the geometric plane containing the mean orbit of the Earth around the Sun...
, a line which intersects Gemini roughly at the midpoint of the constellation, just below Castor and Pollux.
Stars
The brightest stars in Gemini are
CastorCastor is the second brightest star in the constellation Gemini and one of the brightest stars in the night sky. Although it has the Bayer designation "alpha", it is actually fainter than Beta Geminorum...
and
PolluxPollux is an orange giant star approximately 34 light-years from the Earth in the constellation of Gemini . Pollux is the brightest star in the constellation, brighter than Castor...
. Although Castor has the
Bayer designationA Bayer designation is a stellar designation in which a specific star is identified by a Greek letter, followed by the genitive form of its parent constellation's Latin name...
"Alpha", it is actually the second brightest in the constellation after Pollux. Castor is a sextuple
star systemA star system or stellar system is a small number of stars which orbit each other, bound by gravitational attraction. A large number of stars bound by gravitation is generally called a star cluster or galaxy, although, broadly speaking, they are also star systems.-Binary star systems:A stellar...
. Pollux has an
extrasolar planetAn extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...
revolving around it, as do two other stars in Gemini,
HD 50554HD 50554 is a star approximately away in the constellation Gemini.- Star :HD 50554 is a yellow-white main-sequence star [F8V] that currently fuse hydrogen in its core. Since the star is 7th magnitude, it is not visible to the unaided eye, but with binoculars or a telescope, it should be easy to...
, and
HD 59686HD 59686 is a 5th magnitude star approximately 316 light years away in the constellation Gemini.- Star :It is an orange giant meaning it has ceased fusing hydrogen in its core and on its way to becoming a red giant...
. Another noteworthy star is
MekbudaZeta Geminorum is a star in the constellation Gemini. It has the traditional name Mekbuda.The name Mekbuda has roots in ancient Arabic where it and the star Mebsuta were the paws of a lion...
(ζ Gem), a
supergiantSupergiants are among the most massive stars. They occupy the top region of the Hertzsprung-Russell diagram. In the Yerkes spectral classification, supergiants are class Ia or Ib . They typically have bolometric absolute magnitudes between -5 and -12...
with a radius that is 60 times solar, making it approximately 220,000 times the size of the
SunThe Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
.
Deep sky objects
To look at Gemini is to look away from the
Milky WayThe Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
; as a result, there are comparatively few deep sky objects of note. The
Eskimo NebulaThe Eskimo Nebula , also known as the Clownface Nebula or Caldwell 39, is a bipolar double-shell planetary nebula . It was discovered by astronomer William Herschel in 1787. The formation resembles a person's head surrounded by a parka hood. It is surrounded by gas that composed the outer layers of...
and
Medusa NebulaThe Medusa Nebula is a large planetary nebula in the constellation of Gemini on the Canis Minor border. It also known as Abell 21 and Sharpless 274. It was originally discovered in 1955 by UCLA astronomer George O. Abell, who classified it as an old planetary nebula...
,
Messier objectThe Messier objects are a set of astronomical objects first listed by French astronomer Charles Messier in 1771. The original motivation of the catalogue was that Messier was a comet hunter, and was frustrated by objects which resembled but were not comets...
M35Messier 35 is an open cluster in the constellation Gemini. It was discovered by Philippe Loys de Chéseaux in 1745 and independently discovered by John Bevis before 1750...
and
GemingaGeminga is a neutron star approximately 250 parsecs away from the Sun in the constellation Gemini. Its name is both a contraction of "Gemini gamma-ray source", and gh'è minga "it's not there" in the Lombard dialect of Milan .- Pulsar :...
are those that attract the most attention. The Eskimo and Medusa nebulae are both
planetary nebulaA planetary nebula is an emission nebula consisting of an expanding glowing shell of ionized gas ejected during the asymptotic giant branch phase of certain types of stars late in their life...
e, the one approximately 2,870
light yearsLight Years is the seventh studio album by Australian recording artist Kylie Minogue. It was released on 25 September 2000 by Parlophone and Mushroom Records. The album's style was indicative of her return to "mainstream pop dance tunes"....
away and the other 1,500 light years distant. M35 is an open
star clusterStar clusters or star clouds are groups of stars. Two types of star clusters can be distinguished: globular clusters are tight groups of hundreds of thousands of very old stars which are gravitationally bound, while open clusters, more loosely clustered groups of stars, generally contain less than...
which was discovered in the year 1745 by Swiss astronomer Philippe Loys de Chéseaux. And Geminga is a
neutron starA neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...
approximately 550 light years from
EarthEarth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
. Other objects of note are
NGC 2129NGC 2129 is an open cluster in the constellation Gemini. It has an angular distance of 2.5 arcminutes and is approximately 2.2 ± 0.2 kpc from the Sun inside the Local spiral arm. At that distance, the angular size of the cluster corresponds to a diameter of about 10.4 light years...
,
NGC 2158NGC 2158 is an open cluster in the constellation of Gemini. It is located southwest of open cluster Messier 35, and is believed to be just over 1 billion years old.-External links:*...
, NGC 2266, NGC 2331,
NGC 2355NGC 2355 is an old open cluster in the constellation Gemini.It is approximately a billion years old and is located about 5,400 light years from the Solar System and 1,100 ly above the plane of the Milky Way galaxy. At that distance, the angular size of the cluster halo corresponds to a radius of...
, and NGC 2395.
Mythology
In Babylonian astronomy, the stars Castor and Pollux were known as the Great Twins (MUL.MASH.TAB.BA.GAL.GAL). The Twins were regarded as minor gods and were called Meshlamtaea and Lugalirra, meaning respectively 'The One who has arisen from the Underworld' and the 'Mighty King'. Both names can be understood as titles of Nergal, the major Babylonian god of plague and pestilence who was king of the Underworld.
In
Greek mythologyGreek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...
, Gemini was associated with the myth of
Castor and PolluxIn Greek and Roman mythology, Castor and Pollux or Polydeuces were twin brothers, together known as the Dioscuri . Their mother was Leda, but Castor was the mortal son of Tyndareus, king of Sparta, and Pollux the divine son of Zeus, who visited Leda in the guise of a swan...
, collectively known as the Dioscuri. When Castor died, because he was mortal, Pollux begged his father Zeus to give Castor immortality and he did, by uniting them together in the heavens.
Visualizations
Gemini is dominated by
CastorCastor is the second brightest star in the constellation Gemini and one of the brightest stars in the night sky. Although it has the Bayer designation "alpha", it is actually fainter than Beta Geminorum...
and
PolluxPollux is an orange giant star approximately 34 light-years from the Earth in the constellation of Gemini . Pollux is the brightest star in the constellation, brighter than Castor...
, 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); it is a second magnitude star and represents Castor's head. The twin to the left is Pollux, whose brightest star is β Geminorum (more commonly called Pollux); it 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 GeminorumIota Geminorum is a Class G9, fourth-magnitude star in the constellation Gemini. It is called by the proper name Propus, meaning "forefoot" in Latin....
, Pollux's left hand by
κ GeminorumKappa Geminorum is a Class G8, fourth-magnitude star in the constellation Gemini. Kappa Geminorum is a multiple star system located about 140 light-years from Earth....
: all three of these stars are of the fourth magnitude. Pollux's pelvis is represented by star
δ GeminorumDelta Geminorum is a star in the constellation Gemini. It has the traditional name Wasat. The traditional name comes from the Arabic word for "middle"....
, Pollux's right knee by
ζ GeminorumZeta Geminorum is a star in the constellation Gemini. It has the traditional name Mekbuda.The name Mekbuda has roots in ancient Arabic where it and the star Mebsuta were the paws of a lion...
, Pollux's right foot by
γ GeminorumGamma Geminorum is the second brightest star in the constellation Gemini. It has the traditional names Alhena and Almeisan....
, Pollux's left knee by
λ GeminorumLambda Geminorum is a Class A3, fourth-magnitude star in the constellation Gemini. Lambda Geminorum is a variable star located about 95 light-years from Earth....
, and Pollux's left foot by
ξ GeminorumXi Geminorum is a star in the constellation Gemini. It has the traditional name Alzirr, meaning "the button" in Arabic.This star, along with γ Gem , μ Gem , ν Gem and η Gem were Al Han'ah, "the brand"...
. 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 GeminorumTau Geminorum is a star in the Gemini constellation. It is an orange giant of the spectral type K2III, meaning it is probably fusing carbon and oxygen in its core to form iron and nickel. It has the apparent magnitude of 4.40, visible to the naked eye with moderate difficulty. The absolute...
, Castor's left hand by
ι GeminorumIota Geminorum is a Class G9, fourth-magnitude star in the constellation Gemini. It is called by the proper name Propus, meaning "forefoot" in Latin....
(which he shares with Pollux), Castor's right hand by
θ GeminorumTheta Geminorum is a Class A3, fourth-magnitude star in the constellation Gemini. Theta Geminorum is a binary star with components of magnitudes 3.60 and 5.18, separated by 2.9 arcseconds. This stellar system is located about 200 light-years from Earth....
: all three of these stars are of the fourth magnitude. Castor's pelvis is represented by the star
ε GeminorumEpsilon Geminorum is a star in the constellation of Gemini. It has the traditional name Mebsuta ....
, Castor's left foot by ν Geminorum, and Castor's right foot by
μ GeminorumMu Geminorum is a star in the constellation Gemini, approximately 230 light years away from Earth. It has the traditional name Tejat Posterior, which means back foot, because it is the foot of Castor, one of the Gemini twins...
and
η GeminorumEta Geminorum is a triple star system in the constellation Gemini. It has the traditional names Tejat Prior, Propus and Praepes and Pish Pai ....
: ε, μ, and η Geminorum are of the third magnitude. The brightest star in this constelation is Pollux.
Equivalents
In
Chinese astronomyAstronomy in China has a very long history, with historians considering that "they [the Chinese] were the most persistent and accurate observers of celestial phenomena anywhere in the world before the Arabs."...
, the stars that correspond to Gemini are located in two areas: the
White Tiger of the WestThe White Tiger is one of the Four Symbols of the Chinese constellations. It is sometimes called the White Tiger of the West , and is known as Baihu in Chinese, Byakko in Japanese, Baekho in Korean and Bạch Hổ in Vietnamese...
(西方白虎,
Xī Fāng Bái Hǔ) and the
Vermillion Bird of the SouthThe Vermilion bird is one of the Four Symbols of the Chinese constellations. According to Wu Xing, the Taoist five-elemental system, it represents the fire-element, the direction south, and the season summer correspondingly. Thus it is sometimes called the Vermilion bird of the South...
(南方朱雀,
Nán Fāng Zhū Què).
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
GeminiGemini is the third astrological sign in the Zodiac, which spans the Zodiac between the 60th and 89th degree of celestial longitude. Generally, the Sun transits this area of the zodiac between May 21 to June 20 each year...
from May 21 to June 20, and in
sidereal astrologySidereal and tropical are astronomical terms used to describe two different definitions of a "year". They are also used as terms for two systems of ecliptic coordinates used in astrology....
, from June 16 to July 15.
Namesakes
USS Gemini (AP-75) and
USS Gemini (PHM-6)USS Gemini was the final ship of her class of hydrofoils operated by the U.S. Navy. She was named for the constellation.Pegasus class vessels were designed for high speed and mobility, and carried a powerful armament....
are
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
navy ships named after the constellation.
See also
- Geminga
Geminga is a neutron star approximately 250 parsecs away from the Sun in the constellation Gemini. Its name is both a contraction of "Gemini gamma-ray source", and gh'è minga "it's not there" in the Lombard dialect of Milan .- Pulsar :...
, Gemini gamma-ray source
- Gemini (Chinese astronomy)
- IC 444
IC 444 is a small, 32 square arcminute reflection nebula in the constellation Gemini.-References:* *...
, reflection nebula
- Messier 35
Messier 35 is an open cluster in the constellation Gemini. It was discovered by Philippe Loys de Chéseaux in 1745 and independently discovered by John Bevis before 1750...
open cluster
External links
- The Deep Photographic Guide to the Constellations: Gemini
- Astrojan Astronomical Picture Collection: The clickable Gemini
- WikiSky: Gemini constellation
- Ian Ridpath's Star Tales: Gemini
- APOD
Astronomy Picture of the Day is a website provided by NASA and Michigan Technological University . According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer."The photograph is not necessarily...
Pictures of Gemini and Deep Sky Objects:
- A Spring Sky Over Hirsau Abbey
- The Eskimo Nebula from Hubble
- The Medusa Nebula
- Open Star Clusters M35 and NGC 2158
- NGC 2266: Old Cluster in the NGC