This article is about theastronomical constellation. For theastrological sign, seeCapricorn (astrology). For "Capricornis", the genus of goat/antelope-like mammals, seeSerow.
Visible at latitudes between +60° and −90°. Best visible at 21:00 (9 p.m.) during the month ofSeptember.
Capricornus is one of theconstellations of thezodiac. Its name isLatin for "hornedgoat" or "goathorn" or "having horns like a goat's", and it is commonly represented in the form of asea goat: a mythical creature that is half goat, halffish.
Capricornus is one of the88 modern constellations, and was also one of the 48 constellations listed by the 2nd century astronomerClaudius Ptolemy. Its old astronomical symbol is (♑︎). Under its modern boundaries it is bordered byAquila,Sagittarius,Microscopium,Piscis Austrinus, andAquarius. The constellation is located in an area of sky called theSea or the Water, consisting of many water-related constellations such as Aquarius,Pisces andEridanus. It is the smallest constellation in the zodiac.
Capricornus is a faint constellation, with only one star above magnitude 3; itsalpha star has a magnitude of only 3.6.
The brightest star in Capricornus isδ Capricorni, also called Deneb Algedi, with a magnitude of 2.9, located 39 light-years from Earth. Like several other stars such asDenebola andDeneb, it is named for the Arabic word for "tail or end" (deneb) and “young goat / kid” (al-gedi); its traditional name means "tail to head” or “back to the beginning", which could be related to the Ouroboros or Janus since the zodiac relates to January. Deneb Algedi is aBeta Lyrae variable star (a type ofeclipsing binary). It ranges by about 0.2 magnitudes with a period of 24.5 hours.[3]
The other bright stars in Capricornus range in magnitude from 3.1 to 5.1.α Capricorni is a multiple star. The primary (α2 Cap), 109 light-years from Earth, is a yellow-hued giant star of magnitude 3.6; the secondary (α1 Cap), 690 light-years from Earth, is a yellow-hued supergiant star of magnitude 4.3. The two stars are distinguishable by the naked eye, and both are themselves multiple stars. α1 Capricorni is accompanied by a star of magnitude 9.2; α2 Capricorni is accompanied by a star of magnitude 11.0; this faint star is itself a binary star with two components of magnitude 11. Also called Algedi or Giedi, the traditional names of α Capricorni come from the Arabic word for "the kid", which references the constellation's mythology.[3]
β Capricorni is adouble star also known as Dabih. It is a yellow-hued giant star of magnitude 3.1, 340 light-years from Earth. The secondary is a blue-white hued star of magnitude 6.1. The two stars are distinguishable in binoculars. β Capricorni's traditional name comes from the Arabic phrase for "the lucky stars of the slaughterer," a reference to ritual sacrifices performed by ancient Arabs at theheliacal rising of Capricornus.[4] Another star visible to the naked eye isγ Capricorni, sometimes called Nashira ("bringing good tidings"); it is a white-hued giant star of magnitude 3.7, 139 light-years from Earth.π Capricorni is a double star with a blue-white hued primary of magnitude 5.1 and a white-hued secondary of magnitude 8.3. It is 670 light-years from Earth and the components are distinguishable in a small telescope.[3]
Several galaxies and star clusters are contained within Capricornus.Messier 30 is a globular cluster located 1 degree south of the galaxy group that containsNGC 7103. The constellation also harbors the wide spiral galaxyNGC 6907.
Messier 30 (NGC 7099) is a centrally-condensed globular cluster of magnitude 7.5 . At a distance of 30,000 light-years, it has chains of stars extending to the north that are resolvable in small amateur telescopes.[3]
Onegalaxy group located in Capricornus isHCG 87, a group of at least three galaxies located 400 millionlight-years from Earth (redshift 0.0296). It contains a largeelliptical galaxy, a face-onspiral galaxy, and an edge-on spiral galaxy. The face-on spiral galaxy is experiencing abnormally high rates ofstar formation, indicating that it isinteracting with one or both members of the group. Furthermore, the large elliptical galaxy and the edge-on spiral galaxy, both of which haveactive nuclei, are connected by a stream of stars and dust, indicating that they too are interacting. Astronomers predict that the three galaxies maymerge millions of years in the future to form a giant elliptical galaxy.[5]
The constellation was first attested in depictions on a cylinder-seal from around the 21st century BCE,[6] it was explicitly recorded in theBabylonian star catalogues before 1000 BCE. In theEarly Bronze Age thewinter solstice occurred in the constellation, but due to theprecession of the equinoxes, theDecember solstice now takes place in the constellationSagittarius.[7] The Sun is now in the constellation Capricorn (as distinct from the astrological sign) from late January through mid-February.[3]
Although the solstice during the northern hemisphere's winter no longer takes place while the sun is in theconstellation Capricornus, as it did until 130 BCE, theastrological sign called Capricorn is still used to denote the position of the solstice, and the latitude of the sun's most southerly position continues to be called theTropic of Capricorn, a term which also applies to the line on the Earth at which the sun is directly overhead at local noon on the day of the December solstice.[3]
The planetNeptune was discovered by German astronomerJohann Galle, near Deneb Algedi (δ Capricorni) on 23 September 1846, as Capricornus can be seen best from Europe at 4:00AM in September (although, by modern constellation boundaries established in the early 20th century CE, Neptune lay within the confines of Aquarius at the time of its discovery).
Despite its faintness, the constellation Capricornus has one of the oldest mythological associations, having been consistently represented as ahybrid of a goat and a fish since theMiddle Bronze Age, when theBabylonians usedMULSUḪUR.MAŠ "The Goat-Fish" as a symbol of their godEa.[7][6]
InGreek mythology, the constellation is sometimes identified asAmalthea, the goat that suckled the infantZeus after his mother,Rhea, saved him from being devoured by his father,Cronos. Amalthea's broken horn was transformed into thecornucopia or "horn of plenty".[8]
Capricornus is also sometimes identified asPan, the god with a goat's horns and legs, who saved himself from the monsterTyphon by giving himself a fish's tail and diving into a river.[3]
Capricornus's brighter stars are found on a triangle whose vertices areα2 Capricorni (Giedi),δ Capricorni (Deneb Algiedi), andω Capricorni. Ptolemy's method of connecting the stars of Capricornus has been influential.[9] Capricornus is usually drawn as a goat with the tail of a fish.[3]
Diagram of H.A. Rey's alternative way to connect the stars of the Capricornus constellation
H. A. Rey has suggested an alternative visualization, which graphically shows agoat.[10] The goat's head is formed by the triangle of starsι Cap,θ Cap, andζ Cap. The goat's horn sticks out with starsγ Cap and δ Cap. Star δ Cap, at the tip of the horn, is of the third magnitude. The goat's tail consists of starsβ Cap and α2 Cap: star β Cap being of the third magnitude. The goat's hind foot consists of starsψ Cap and ω Cap. Both of these stars are of the fourth magnitude.
^abEspak, Peeter (2006).Master's Thesis(PDF) (Masters). p. 104.Archived(PDF) from the original on 2022-10-09.
^abRogers, John H. (1998). "Origins of the ancient constellations: I. The Mesopotamian traditions".Journal of the British Astronomical Association.108:9–28.Bibcode:1998JBAA..108....9R.
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