Approximate Position Name/Meaning (Equatorial Coordinates) [Latin (English)] Genitive Form of Latin Name Abbreviation RA (h) δ](°)
Antlia (air pump) Antliae Ant 10 –35
Apus (bird of paradise) Apodis Aps 16 –75
Caelum (sculptor’s chisel) Caeli Cae 5 –40
Camelopardalis (giraffe) Camelopardalis Cam 6 +70
Canes Venatici (hunting dogs) Canum Venaticorum CVn 13 +40
Carina (keel)* Carinae Car 9 –60
Chamaeleon (chameleon) Chamaeleontis Cha 11 –80
Circinus (compasses) Circini Cir 15 –60
Columba (dove) Columbae Col 6 –35
Coma Berenices (Berenice’s hair) Comae Berenices Com 13 +20
Crux (southern cross) Crucis Cru 12 –60
Dorado (swordfish) Doradus Dor 5 –65
Fornax (furnace) Fornacis For 3 –30
Grus (crane) Gruis Gru 22 –45
Horologium (clock) Horologii Hor 3 –60
Hydrus (water snake) Hydri Hyi 2 –75
Indus (Indian) Indi Ind 21 –55
Lacerta (lizard) Lacertae Lac 22 +45
Leo Minor (little lion) Leonis Minoris LMi 10 +35
Lynx (lynx) Lyncis Lyn 8 +45
Mensa (table mountain) Mensae Men 5 –80
Microscopium (microscope) Microscopii Mic 21 –35
Monoceros (unicorn) Monocerotis Mon 7 –5
Musca (fly) Muscae Mus 12 –70
Norma (carpenter’s square) Normae Nor 16 –50
Octans (octant; navigation device) Octantis Oct 22 –85
Pavo (peacock) Pavonis Pav 20 –65
Phoenix (Phoenix; mythical bird) Phoenicis Phe 1 –50
Pictor (painter’s easel) Pictoris Pic 6 –55
Puppis (stern)* Puppis Pup 8 –40
Pyxis (nautical compass)* Pyxidis Pyx 9 –30
Reticulum (net) Reticuli Ret 4 –60
Sculptor (sculptor’s workshop) Sculptoris Scl 0 –30
Scutum (shield) Scuti Sct 19 –10
Sextans (sextant) Sextantis Sex 10 0
Telescopium (telescope) Telescopii Tel 19 –50
Triangulum Australe (southern triangle) Trianguli Australe TrA 16 –65
Tucana (toucan) Tucanae Tuc 0 –65
Vela (sail)* Velorum Vel 9 –50
Volans (flying fish) Volantis Vol 8 –70
Vulpecula (fox) Vulpeculae Vul 20 +25
151
all the stars in the night sky. They even used a special word,
amorphotoi (meaning “unformed”), to describe the spaces in
the night sky populated by dim stars between the prominent groups of stars constituting the ancient constellations. The Ancient Constellations table contains a list of the 48 ancient Greek constellations.
Today astronomers officially recognize all but one of these ancient star patterns. The somewhat cumbersome con- stellation Argo Navis has now been broken up into four new constellations (as discussed shortly). By convention, when astronomers formally refer to a constellation such as Centau- rus in English, they use the proper name “The Centaur.” Sim- ilarly, when astronomers wish to describe celestial objects within a particular constellation they use the genitive form of the constellation’s Latin name—as, for example, Alpha Cen-
tauri (α Cen) to describe the brightest (binary) star in the
constellation Centaurus.
Astronomers in the Roman Empire were quite content to accept and use Greek celestial figures and constellations. Their primary contribution was the use of “Roman” (Latin) names for many familiar celestial objects, a tradition and her- itage still followed by astronomers today. Therefore, as part of the Pax Romana, the use of the 48 ancient Greek constel- lations spread throughout the civilized (Western) world.
As the Roman Empire collapsed and the Dark Ages spread throughout western Europe, knowledge of Greek astronomy survived and began to flourish in Arab lands. Arab astronomers discovered Ptolemy’s great work, translat- ed it, and then renamed it The Almagest. By so doing, they preserved the astronomical heritage of the 48 ancient Greek constellations. Arab astronomers also refined and embel- lished the knowledge base of ancient Greek naked eye astron- omy by providing new star names and more precise observations. Finally, the astronomical heritage of the ancient constellations returned to Europe just as people there were awakening from the Dark Ages, experiencing the Renais- sance, and paving the way for the scientific revolution.
As part of the explosive interest in astronomy that occurred at the start of the scientific revolution, the German astronomer JOHANN BAYER published the important work
Uranometria in 1603. This book was the first major star cat-
alog for the entire celestial sphere. Bayer charted more than 2,000 stars visible to the naked eye and introduced the prac- tice of assigning Greek letters (such as alpha α, beta β, and gamma γ) to the main stars in each constellation, usually in an approximate (descending) order of their brightness. Expanding the legacy of 48 constellations from ancient Greece, Bayer named 12 new southern hemisphere constella- tions: Apus, Chamaeleon, Dorado, Grus, Hydrus, Indus, Musca (originally called Apis [bee] by Bayer), Pavo, Phoenix, Triangulum Australe, Tucana, and Volans. The Modern Con- stellations Table describes these new constellations as well as the other modern constellations officially recognized by the International Astronomical Union since 1929.
Using the newly invented astronomical telescope the Polish-German astronomer JOHANNESHEVELIUSfilled in some
of the empty spaces (amorphotoi) in the Northern Hemi- sphere of the celestial sphere by identifying the following new constellations: Canes Venatici, Lacerta, Lynx, and Leo Minor. Then, in the 18th century the French astronomer Abbé
NICOLAS-LOUIS DELACAILLEdescribed 14 new constellations
he found in the Southern Hemisphere and named some of them after scientific artifacts and instruments emerging dur- ing the period. His newly identified constellations included: Antlia, Caelum, Circinus, Fornax, Horologium, Mensa, Microscopium, Norma, Octans, Pictor, Pyxis, Reticulum, Sculptor, and Telescopium. Lacaille was a precise technophile, so many of the names he carefully selected for his newly iden- tified constellations were long and detailed. For example, Antlia (the Air Pump) honors the device invented by the British scientist Robert Boyle (1627–91), and Fornax actually means “the Laboratory Furnace.” By international agree- ment, modern astronomers generally use shortened versions of Lacaille’s original names—such as simply “Furnace” instead of “Laboratory Furnace” for Fornax. This is done for ease in technical communications; it does not represent an attempt to detract from Lacaille’s important work.
Lacaille and other astronomers of his era also dismantled the cumbersome ancient constellation Argo Navis (ship of Jason and the Argonauts) and carved up the stars in this large Southern Hemisphere constellation into four smaller, more manageable ones whose names retain the original nautical theme: Carina (the Keel), Puppis (the Stern), Pyxis (the Nauti- cal Compass), and Vela (the Sail).
Today astronomers have 88 officially recognized constel- lations. All of these constellations may be found (in alphabet- ical order) by combining the two Constellations Tables. The tables include the position of each constellation on the celes- tial sphere as expressed in the equatorial coordinates (right ascension [RA] and declination [δ]) that correspond to the approximate center of the constellation.
See alsoZODIAC.
Constellation X-Ray Observatory
(Constellation-X) Thefuture NASA scientific mission that involves an array of X- ray telescopes working together in tight orbit to improve by a hundredfold how astronomers and astrophysicists observe the universe in the X-ray portion of the electromagnetic spec- trum. The current plan calls for four satellites operating in unison to generate the observing power of one giant space- based X-ray telescope. (See figure, page 152.) The Constella-
tion-X satellites will house high-resolution X-ray spectroscopy telescopes that collect high-energy X-rays pro- duced by cataclysmic cosmic events and then interpret those event-related X-rays as spectra. Scientists regard X-ray spec- tra as the fingerprints of the chemicals producing the X-rays.
When observations begin (about 2010) data from Con-
stellation-X will help scientists resolve many pressing issues
that currently challenge their understanding of the laws of physics. For example, Constellation-X observations of iron spectra in the vicinity of suspected massive black holes will help astrophysicists test ALBERT EINSTEIN’s theory of general
relativity in an environment of extreme gravity. Constellation-
X will also help scientists determine how black holes evolve
and generate energy, thereby providing important informa- tion about the total energy content of the universe. With data from this observatory scientists will also be able to investigate galaxy formation, the evolution of the universe on large scales, the nature of dark matter, and how the universe recy- cles its matter and energy—for example, how heavier ele-
ments from the cores of exploding stars eventually form plan- ets and comets and how the gas from old stars helps make new ones.
Like all X-ray telescopes, Constellation-X must operate in outer space because X-ray photons from cosmic phenome- na do not penetrate very far into Earth’s atmosphere. The sci- entists and engineers who designed Constellation-X wanted to create an X-ray observatory capable of collecting as much X-ray “light” as possible, imitating to the greatest extent pos- sible the way giant ground-based optical telescopes such as the Keck telescope use their large optics to gather as much visible light as possible from distant celestial objects. These demanding requirements led NASA personnel to select a unique multisatellite design for Constellation-X. The four satellites will be of identical low-mass design, allowing each spacecraft to be launched individually or possibly in pairs. The construction of four identical spacecraft reduces the overall cost of the mission and also avoids the risk of com- plete mission failure should a single launch abort occur. Once successfully co-orbited, the combined capability of Constella-
tion-X’s four X-ray telescopes will provide a level of sensitivi-
ty that is 100 times greater than any past or current X-ray satellite mission.
Essentially, scientists using Constellation-X will be able to collect more data in an hour than they can now collect in days or weeks with current space-based X-ray telescopes. Of special importance to astronomers and astrophysicists is the fact that Constellation-X will also allow them to dis- cover and analyze thousands of faint X-ray-emitting sources, not just the bright sources available today. NASA’s
Constellation X-Ray Observatory promises to stimulate a
revolution in X-ray astronomy and a much deeper under- standing of energetic phenomena taking place throughout the universe.
See also CHANDRA X-RAY OBSERVATORY; ROSSI X-RAY
TIMING EXPLORER; XMM-NEWTON SPACECRAFT; X-RAY ASTRONOMY.