My Astronomy Blogs

What Are Constellations?

The word Constellation comes from Latin and means “set of stars”, so simply put, a Constellation is just a recognizable pattern of stars in the night sky. It’s also important to understand that the constellation does not just include the bright stars with the imaginary lines forming various shapes. A constellation also has set boundaries and all the astronomical objects in that region are considered to be part of that constellation.

For example, in the following image of the constellation Orion, the lines that represent the shape of the constellation are gray and the boundary of the constellation is green. All the stars and other objects within that boundary are part of the constellation.

There are 88 constellations in the sky giving complete coverage to every point on the celestial globe. So every star and object in the sky falls within the boundaries of one of the 88 constellations.

Where Did Constellations Come From?

Of the 88 constellations, 50 of them are ancient, with names that are Latin in origin, and date from the Roman Empire. However many of the constellations names originated from the distant past, from ancient Egypt or Babylon, as far back as before 3000 B.C. The other 38 constellations are considered to be modern and were identified later by astronomers between the 15th and 17th centuries. Some examples of these are Pavo the Peacock, or Telescopium the Telescope.

By the early 19th century there was a lot of confusion over constellations and their boundaries. Many cultures having their own set of constellations and names, and at the time many schools of astronomy had prepared their own star maps using their own boundaries. To help resolve this confusion in 1930 the International Astronomical Union published star maps with names and boundaries officially assigned to 88 constellations providing coverage to the entire sky. These constellation boundaries are used today by modern astronomers.

Constellations of the Zodiac

The Sun, Moon and Planets follow a consistent path through the sky and throughout the constellations, this path is known as the ecliptic. The constellations that follow the line of the ecliptic are known as the constellations of the Zodiac. According to astrology there are 12 zodiac constellation but astronomically speaking there are actually 13 constellations: Capricornus, Aquarius, Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius, and Ophiuchus, the 13th constellation being Ophiuchus which is not one of the astrological constellations.

If you are into astrology and like to check your Horoscope, then the 12 constellations of the Zodiac have special significance. However, for astronomers the 13 constellations of the Zodiac are no more important as all the other constellations.

Visibility of the Constellations

Not all the constellations are visible throughout the year, if you observe the constellations from month to month you will notice that they are continually shifting to the west. This westward shift is caused by the earths orbit around the sun. The dark side of the earth is pointing in different directions as the earth goes around the sun.

Try An Experiment

To illustrate this shift you could try a simple experiment using a lamp, to represent the sun, and a ball, to represent the earth. Place the lamp in the middle of the room, then hold the ball as you walk around the lamp. As you walk (orbit) around the lamp, notice that the dark side of the ball, the side of the ball that is not getting light from the lamp, will face each wall as you move around the lamp. This is the same way it works as Earth goes around the sun and is the reason why some constellations are only visible during certain months of the year.

Circumpolar Constellations

Some constellations are visible throughout the year, these are considered to be circumpolar because they never set below the horizon. If you are in the northern hemisphere then the major circumpolar constellations are: Cassiopeia, Cepheus, Draco, Ursa Major, and Ursa Minor. If you are in the southern hemisphere then the major circumpolar constellations are: Carina, Centaurus, and Crux.

Why Are Constellations Important?

For modern professional and amateur astronomers having knowledge of where things are in the night sky is essential. Knowing where the constellations are helps us to orient ourselves and recognize specific stars and patterns in the night sky. When looking at objects in the night sky the constellation is part of the objects address. For example, when there is a new comet in town I want to know where it is, if know what constellation its in then I know where to start looking for it.

If you are just getting started with astronomy don’t run out and buy you a new smart telescope (at least now yet). First get some star charts and start identifying the constellations and learning the names of some of the brighter stars in those constellations.

List Of Constellations

Name (Latin)	Abbreviation	Genitive	Description
Andromeda	And	Andromedae	Chained Maiden / Princess of Ethiopia
Antlia	Ant	Antliae	Air pump
Apus	Aps	Apodis	Bird of Paradise
Aquila	Aql	Aquilae	Eagle
Aquarius	Aqr	Aquarii	Water Bearer
Ara	Ara	Arae	Altar
Aries	Ari	Arietis	Ram
Auriga	Aur	Aurigae	Charioteer
Boötes	Boo	Boötis	Herdsman
Canis Major	CMa	Canis Majoris	Great Dog
Canis Minor	CMi	Canis Minoris	Canis Minoris
Canes Venatici	CVn	Canum Venaticorum	Hunting Dogs
Caelum	Cae	Caeli	Engraving Tool
Camelopardalis	Cam	Camelopardalis	Giraffe
Capricornus	Cap	Capricorni	Sea Goat
Carina	Car	Carinae	Keel
Cassiopeia	Cas	Cassiopeiae	Seated Queen
Centaurus	Cen	Centauri	Centaur
Cepheus	Cep	Cephei	King
Cetus	Cet	Ceti	Sea Monster
Chamaeleon	Cha	Chamaeleontis	Chameleon
Circinus	Cir	Circini	Drafting Compass
Cancer	Cnc	Cancri	Cancri
Columba	Col	Columbae	Columbae
Coma Berenices	Com	Comae Berenices	Berenice’s Hair
Corona Austrina	CrA	Coronae Australis	Southern Crown
Corona Borealis	CrB	Coronae Borealis	Northern Crown
Crater	Crt	Crateris	Crateris
Crux	Cru	Crucis	Southern Cross
Corvus	Crv	Corvi	Corvi
Cygnus	Cyg	Cygni	Swan
Delphinus	Del	Delphini	Dolphin
Dorado	Dor	Doradus	Dolphinfish
Draco	Dra	Draconis	Draconis
Equuleus	Equ	Equulei	Little Horse
Eridanus	Eri	Eridani	River
Fornax	For	Fornacis	Furnace
Gemini	Gem	Geminorum	Twins
Grus	Gru	Gruis	Crane
Hercules	Her	Herculis	Hercules
Horologium	Hor	Horologii	Clock
Hydra	Hya	Hydrae	Water Snake
Hydrus	Hyi	Hydri	Male Water Snake
Indus	Ind	Indi	Indian
Leo Minor	LMi	Leonis Minoris	Lesser Lion
Lacerta	Lac	Lacertae	Lizard
Leo	Leo	Leonis	Lion
Lepus	Lep	Leporis	Hare
Libra	Lib	Librae	Scales
Lupus	Lup	Lupi	Wolf
Lynx	Lyn	Lyncis	Lynx
Lyra	Lyr	Lyrae	Lyre or harp
Mensa	Men	Mensae	Table
Microscopium	Mic	Microscopii	Microscope
Monoceros	Mon	Monocerotis	Unicorn
Musca	Mus	Muscae	Fly
Norma	Nor	Normae	Carpenter’s Square
Octans	Oct	Octantis	Octant
Ophiuchus	Oph	Ophiuchi	Serpent Bearer
Orion	Ori	Orionis	Hunter
Pavo	Pav	Pavonis	Peacock
Pegasus	Peg	Pegasi	Winged Horse
Perseus	Per	Persei	Hero
Phoenix	Phe	Phoenicis	Phoenix
Pictor	Pic	Pictoris	Painter
Piscis Austrinus	PsA	Piscis Austrini	Southern Fish
Pisces	Psc	Piscium	Fishes
Puppis	Pup	Puppis	Stern
Pyxis	Pyx	Pyxidis	Magnetic Compass
Reticulum	Ret	Reticulii	Reticle
Sculptor	Scl	Sculptoris	Sculptor
Scorpius	Sco	Scorpii	Scorpion
Scutum	Sct	Scuti	Shield
Serpens	Ser	Serpentis	Serpent
Sextans	Sex	Sextantis	Sextant
Sagitta	Sge	Sagittae	Arrow
Sagittarius	Sgr	Sagittarii	Archer
Taurus	Tau	Tauri	Bull
Telescopium	Tel	Telescopii	Telescope
Triangulum Australe	TrA	Trianguli Australis	Southern Triangle
Triangulum	Tri	Trianguli	Triangle
Tucana	Tuc	Tucanae	Toucan
Ursa Major	UMa	Ursae Majoris	Great Bear
Ursa Minor	UMi	Ursae Minoris	Lesser Bear
Vela	Vel	Velorum	Sails
Virgo	Vir	Virginis	Maiden
Volans	Vol	Volantis	Flying Fish
Vulpecula	Vul	Vulpeculae	Fox