Constellation

constellationsEuropean constellationModern constellationMCAdark cloud constellations42 constellationsconstellation boundariesconstellation namedark area or cloudsDark-cloud constellations
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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Aratus

AratosAratus of SoliAratus Solensis
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. Greek astronomy essentially adopted the older Babylonian system in the Hellenistic era, first introduced to Greece by Eudoxus of Cnidus in the 4th century BC. The original work of Eudoxus is lost, but it survives as a versification by Aratus, dating to the 3rd century BC. The most complete existing works dealing with the mythical origins of the constellations are by the Hellenistic writer termed pseudo-Eratosthenes and an early Roman writer styled pseudo-Hyginus.
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, probably dates back to prehistory.
Babylonian astronomy seemed to have focused on a select group of stars and constellations known as Ziqpu stars.

Taurus (constellation)

TaurusTauriTaurus constellation
Examples 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.

Southern celestial hemisphere

southern skysouthern hemispheresouthern skies
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.

Carina (constellation)

Carinaconstellation CarinaCar
Examples 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.
Carina is a constellation in the southern sky.

Asterism (astronomy)

asterismasterismsconstellation
Examples 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.
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.

Vela (constellation)

VelaFalse Crossconstellation Vela
Examples 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.
Vela is a constellation in the southern sky.

Orion (constellation)

Orionconstellation of OrionOrion constellation
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, probably dates back to prehistory.
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 MaggioreBear
Another example is the popular northern asterism 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.

Hyades (star cluster)

HyadesHyades clusterHyades star cluster
Examples 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.

Johannes Hevelius

HeveliusHevelianaHevelianischen
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.

Big Dipper

Northern DipperPloughBeidou
Another example is the popular northern asterism 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) 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 PtolemyPtolemaicPtol.
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.
Books VII and VIII cover the motions of the fixed stars, including precession of the equinoxes. They also contain a star catalogue of 1022 stars, described by their positions in the constellations, together with ecliptic longitude and latitude. Ptolemy states that the longitudes (which increase due to precession) are for the beginning of the reign of Antoninus Pius (138 AD), whereas the latitudes do not change with time. (But see below, under The star catalog.) The constellations north of the zodiac and the northern zodiac constellations (Aries through Virgo) are in the table at the end of Book VII, while the rest are in the table at the beginning of Book VIII. The brightest stars were marked first magnitude (m = 1), while the faintest visible to the naked eye were sixth magnitude (m = 6). Each numerical magnitude was considered twice the brightness of the following one, which is a logarithmic scale. (The ratio was subjective as no photodetectors existed.) This system is believed to have originated with Hipparchus. The stellar positions too are of Hipparchan origin, despite Ptolemy's claim to the contrary.

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 starsever-visible
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 clusterM45the Pleiades
Examples 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.

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
Some of these were combined with Greek and Babylonian astronomical systems culminating in the Zodiac of Dendera, but it remains unclear when this occurred, but most were placed during the Roman period between 2nd to 4th centuries AD. 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 bakiu) are 36 groups of stars (small constellations) used in the Ancient Egyptian astronomy.

Mazzaroth

mazalot
The term Mazzaroth מַזָּרוֹת, translated as a garland of crowns, is a hapax legomenon in Job 38:32, and it might refer to the zodiacal constellations.
but its context is that of astronomical constellations, and it is often interpreted as a term for the zodiac or the constellations thereof.

Catasterismi

catasterismcatasterisedpseudo-Eratosthenes
Greek astronomy essentially adopted the older Babylonian system in the Hellenistic era, first introduced to Greece by Eudoxus of Cnidus in the 4th century BC. The original work of Eudoxus is lost, but it survives as a versification by Aratus, dating to the 3rd century BC. The most complete existing works dealing with the mythical origins of the constellations are by the Hellenistic writer termed pseudo-Eratosthenes and an early Roman writer styled pseudo-Hyginus.
Catasterismi (Greek Καταστερισμοί Katasterismoi, "placings among the stars") is an Alexandrian prose retelling of the mythic origins of stars and constellations, as they were interpreted in Hellenistic culture.

Zodiac

signs of the zodiactropical zodiaczodiacal signs
Twelve ancient constellations belong to the zodiac (straddling the ecliptic, which the Sun, Moon, and planets all traverse).
The zodiacal signs are distinct from the constellations associated with them, not only because of their drifting apart due to the precession of equinoxes but also because the physical constellations take up varying widths of the ecliptic, so the Sun is not in each constellation for the same amount of time.

Chinese constellations

Southern AsterismsExotic BirdThe Southern Asterisms
These constellations are some of the most important observations of Chinese sky, attested from the 5th century BC. Parallels to the earliest Babylonian (Sumerian) star catalogues suggest that the ancient Chinese system did not arise independently.
Traditional Chinese astronomy has a system of dividing the celestial sphere into asterisms or constellations, known as "officials" (Chinese xīng guān).

Babylonian star catalogues

earliest known star cataloguesMULBabylonians
The oldest Babylonian star catalogues of stars and constellations date back to the beginning in the Middle Bronze Age, most notably the Three Stars Each texts and the MUL.APIN, an expanded and revised version based on more accurate observation from around 1000 BC. However, the numerous Sumerian names in these catalogues suggest that they built on older, but otherwise unattested, Sumerian traditions of the Early Bronze Age.
A few of the constellation names in use in modern astronomy can be traced to Babylonian sources via Greek astronomy.