Constellation

constellationsEuropean constellationModern constellationMCAdark cloud constellations42 constellationsconfiguration of the stars overheadconstellation boundariesconstellation namedark area or clouds
A constellation is a group of stars that forms an imaginary outline or pattern on the celestial sphere, typically representing an animal, mythological person or creature, a god, or an inanimate object.wikipedia
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Star

starsstellarmassive star
A constellation is a group of stars that forms an imaginary outline or pattern on the celestial sphere, typically representing an animal, mythological person or creature, a god, or an inanimate object.
Historically, the most prominent stars were grouped into constellations and asterisms, the brightest of which gained proper names.

Aratus

Aratus of SoliAratus SolensisAratos
They are given in Aratus' work Phenomena and Ptolemy's Almagest, though their origin probably predates these works by several centuries. It is roughly based on the traditional Greek constellations listed by Ptolemy in his Almagest in the 2nd century and Aratus' work Phenomena, with early modern modifications and additions (most importantly introducing constellations covering the parts of the southern sky unknown to Ptolemy) by Petrus Plancius (1592, 1597/98 and 1613), Johannes Hevelius (1690) and Nicolas Louis de Lacaille (1763), who named fourteen constellations and renamed a fifteenth one.
It describes the constellations and other celestial phenomena.

Babylonian astronomy

Babylonian astronomersBabylonianastronomer
The origins of the zodiac remain historically uncertain; its astrological divisions became prominent c. 400 BC in Babylonian or Chaldean astronomy,.
Babylonian astronomy seemed to have focused on a select group of stars and constellations known as Ziqpu stars.

Taurus (constellation)

TaurusTaurus constellationToro
Examples of asterisms include the Pleiades and Hyades within the constellation Taurus and the False Cross split between the southern constellations Carina and Vela, or Venus' Mirror in the constellation of Orion.
Taurus (Latin for "the Bull") is one of the constellations of the zodiac, which means it is crossed by the plane of the ecliptic.

Carina (constellation)

CarinaCarina constellationconstellation Carina
Examples of asterisms include the Pleiades and Hyades within the constellation Taurus and the False Cross split between the southern constellations Carina and Vela, or Venus' Mirror in the constellation of Orion. The southern False Cross asterism includes portions of the constellations Carina and Vela and the Summer Triangle is composed of the brightest stars in the constellations Lyra, Aquila and Cygnus.
Carina ( (U.S.) (Brit.)) is a constellation in the southern sky.

Southern celestial hemisphere

southern skysouthernsouthern hemisphere
Constellations in the far southern sky were added from the 15th century until the mid-18th century when European explorers began traveling to the Southern Hemisphere.
This arbitrary sphere, on which seemingly fixed stars form constellations, appears to rotate westward around a polar axis due to Earth's rotation.

Vela (constellation)

VelaVela constellationconstellation Vela
Examples of asterisms include the Pleiades and Hyades within the constellation Taurus and the False Cross split between the southern constellations Carina and Vela, or Venus' Mirror in the constellation of Orion. The southern False Cross asterism includes portions of the constellations Carina and Vela and the Summer Triangle is composed of the brightest stars in the constellations Lyra, Aquila and Cygnus.
Vela is a constellation in the southern sky.

Asterism (astronomy)

asterismasterismsFalse Cross
Examples of asterisms include the Pleiades and Hyades within the constellation Taurus and the False Cross split between the southern constellations Carina and Vela, or Venus' Mirror in the constellation of Orion. Other star patterns or groups called asterisms are not constellations per se, but are used by observers to navigate the night sky. The southern False Cross asterism includes portions of the constellations Carina and Vela and the Summer Triangle is composed of the brightest stars in the constellations Lyra, Aquila and Cygnus.
This colloquial definition makes it appear quite similar to a constellation, but they differ mostly in that a constellation is an officially recognized area of the sky, while an asterism is a visually obvious collection of stars and the lines used to mentally connect them; as such, asterisms do not have officially determined boundaries and are therefore a more general concept which may refer to any identified pattern of stars.

Orion (constellation)

OrionOrion constellationconstellation of Orion
Where possible, these modern constellations usually share the names of their Graeco-Roman predecessors, such as Orion, Leo or Scorpius.
Orion is a prominent constellation located on the celestial equator and visible throughout the world.

Astrology

astrologerastrologicalastrologers
The origins of the zodiac remain historically uncertain; its astrological divisions became prominent c. 400 BC in Babylonian or Chaldean astronomy,.
Farmers addressed agricultural needs with increasing knowledge of the constellations that appear in the different seasons—and used the rising of particular star-groups to herald annual floods or seasonal activities.

Ursa Major

Great BearOrsa MaggioreUrsa Major constellation
Another example is the northern asterism popularly known as the Big Dipper (US) or the Plough (UK), composed of the seven brightest stars within the area of the IAU-defined constellation of Ursa Major.
Ursa Major (also known as the Great Bear) is a constellation in the northern sky, whose associated mythology likely dates back into prehistory.

Johannes Hevelius

HeveliusJan HeweliuszJohan Hevelius
It is roughly based on the traditional Greek constellations listed by Ptolemy in his Almagest in the 2nd century and Aratus' work Phenomena, with early modern modifications and additions (most importantly introducing constellations covering the parts of the southern sky unknown to Ptolemy) by Petrus Plancius (1592, 1597/98 and 1613), Johannes Hevelius (1690) and Nicolas Louis de Lacaille (1763), who named fourteen constellations and renamed a fifteenth one.
As an astronomer, he gained a reputation as "the founder of lunar topography", and described ten new constellations, seven of which are still used by astronomers.

Hyades (star cluster)

HyadesHyades clusterHyades star cluster
Examples of asterisms include the Pleiades and Hyades within the constellation Taurus and the False Cross split between the southern constellations Carina and Vela, or Venus' Mirror in the constellation of Orion.
From the perspective of observers on Earth, the Hyades Cluster appears in the constellation Taurus, where its brightest stars form a "V" shape along with the still-brighter Aldebaran.

Aquila (constellation)

AquilaAquilaeAql
The southern False Cross asterism includes portions of the constellations Carina and Vela and the Summer Triangle is composed of the brightest stars in the constellations Lyra, Aquila and Cygnus.
Aquila is a constellation on the celestial equator.

Lyra

Lyramong the starsConstellation of Orpheus
The southern False Cross asterism includes portions of the constellations Carina and Vela and the Summer Triangle is composed of the brightest stars in the constellations Lyra, Aquila and Cygnus.
Lyra (Latin for lyre, from Greek λύρα) is a small constellation.

Cygnus (constellation)

CygnusCygnus constellationconstellation of Cygnus
The southern False Cross asterism includes portions of the constellations Carina and Vela and the Summer Triangle is composed of the brightest stars in the constellations Lyra, Aquila and Cygnus.
Cygnus is a northern constellation lying on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan.

Big Dipper

Northern DipperThe PloughPlough
Another example is the northern asterism popularly known as the Big Dipper (US) or the Plough (UK), composed of the seven brightest stars within the area of the IAU-defined constellation of Ursa Major.
The Big Dipper (US, Canada) or the Plough (UK, Ireland) is a large asterism consisting of seven bright stars of the constellation Ursa Major; six of them are of second magnitude and one, Megrez, of third magnitude.

Ptolemy

Claudius PtolemyClaudius PtolemaeusPtolemaic
They are given in Aratus' work Phenomena and Ptolemy's Almagest, though their origin probably predates these works by several centuries.
Its list of forty-eight constellations is ancestral to the modern system of constellations, but unlike the modern system they did not cover the whole sky (only the sky Hipparchus could see).

Almagest

cataloghis book on astronomyMagna Syntaxis
They are given in Aratus' work Phenomena and Ptolemy's Almagest, though their origin probably predates these works by several centuries.

Flamsteed designation

designationFlamsteedcatalogue of stars
The Flamsteed designation of a star, for example, consists of a number and the genitive form of the constellation name.
Each star is assigned a number and the Latin genitive of the constellation it lies in (see 88 modern constellations for a list of constellations and the genitive forms of their names).

Circumpolar constellation

circumpolarcircumpolar starsconstellation which takes in the southern pole
From the North Pole or South Pole, all constellations south or north of the celestial equator are circumpolar.
In astronomy, a circumpolar constellation is a constellation (group of stars) that never sets below the horizon, as viewed from a location on Earth.

Pleiades

Pleiades star clusterThe PleiadesPleiades cluster
Examples of asterisms include the Pleiades and Hyades within the constellation Taurus and the False Cross split between the southern constellations Carina and Vela, or Venus' Mirror in the constellation of Orion.
Some Greek astronomers considered them to be a distinct constellation, and they are mentioned by Hesiod's Works and Days, Homer's Iliad and Odyssey, and the Geoponica.

Summer Triangle

Chinese constellationsthird star forms a symbolic bridge
The southern False Cross asterism includes portions of the constellations Carina and Vela and the Summer Triangle is composed of the brightest stars in the constellations Lyra, Aquila and Cygnus.
The defining vertices of this imaginary triangle are at Altair, Deneb, and Vega, each of which is the brightest star of its constellation (Aquila, Cygnus, and Lyra, respectively).

Proper motion

proper motionsproper-motionhigh proper motion star
Astronomers can predict the past or future constellation outlines by measuring individual stars' common proper motions or cpm by accurate astrometry and their radial velocities by astronomical spectroscopy.
Over the course of centuries, stars appear to maintain nearly fixed positions with respect to each other, so that they form the same constellations over historical time.

Decan

decansDecanic astrologydecan stars
The oldest known depiction of the zodiac showing all the now familiar constellations, along with some original Egyptian constellations, decans, and planets.
The decans (Egyptian baktiu) are 36 groups of stars (small constellations) used in the Ancient Egyptian astronomy.