the constellations
THE LYRE standard star against which and Gamma (γ) Lyrae lies the most
astronomers compare the colour and photographed of Lyra’s celestial
Lyra brightness of all other stars. treasures, the Ring Nebula (see
p.253), or M57.This planetary
SIZE RANKING 52 The finest quadruple star in the nebula is shaped like a smoke
sky – Epsilon (ε) Lyrae (see p.272) – ring, and appears through a small
BRIGHTEST STAR is found three diameters of the full telescope as a disc larger than that
Moon from Vega. Binoculars easily of Jupiter. Larger apertures are
Vega (α) 0.0 show it as a neat pair of 5th- needed to make out the central
GENITIVE Lyrae magnitude white stars, but each of hole. Studies with the Hubble
these has a closer companion that is Space Telescope have revealed
ABBREVIATION Lyr brought into view with a telescope of that the “ring” is in fact a
60–75mm (2.5–3in) aperture and cylinder of gas thrown off from
HIGHEST IN SKY AT 10PM high magnification. All four stars are the central star, oriented almost
linked by gravity and are in long- end-on to the Earth.
July–August term orbit around each other.
THE LYRE
FULLY VISIBLE Two other double stars near Vega
that are easy to identify with
90°N–42°S binoculars are Zeta (ζ) and Delta (δ)
Lyrae, each with components of 4th
Lyra lies on the edge of the Milky and 6th magnitudes. Beta (β) Lyrae is
Way next to Cygnus and is a compact another double star, easily resolved by
constellation of the northern sky. It a small telescope into its cream and
includes Vega, or Alpha (α) Lyrae (see blue components.The brighter star
p.249), which is the fifth-brightest star (the cream one) is an eclipsing binary
in the sky and one of the so-called that fluctuates between magnitudes
Summer Triangle of stars – the other 3.3 and 4.4 every 12.9 days. Many
two being Deneb (in Cygnus) and years of study have established that
Altair (in Aquila).The Lyrid meteors Beta’s two stars are so close that
radiate from a point near Vega around gas from the larger of the pair
21–22 April every year. Lyra falls towards the smaller
represents the stringed instrument companion, and some
played by Orpheus (see panel, below). of it spirals off into
space. Almost
SPECIFIC FEATURES midway
Vega dazzles at magnitude 0.0, between
appearing somewhat blue-white in Beta
colour to the unaided eye. It is the
THE RING NEBULA 4 STRINGED INSTRUMENT 2 THE NIGHT SKY
One of the most famous planetary nebulae in Lyra, dominated by dazzling Vega,
the whole sky, the Ring Nebula, or M57, represents the harp played by
consists of hot gas shed from a central star. Orpheus, the musician of Greek myth.
Its beautiful colours are revealed only on Arab astronomers visualized the
photographs such as this. constellation as an eagle or vulture.
MYTHS AND STORIES
ORPHEUS
Heartbroken Orpheus descended into
the Underworld to retrieve his wife,
Eurydice, who had been killed by a
snake. His songs charmed Hades, god
of the Underworld, who agreed to
release Eurydice provided Orpheus
did not look back as he led her to
the surface. At the last minute,
Orpheus glanced behind him, and
Eurydice faded away. Orpheus then
roamed the Earth, disconsolately
playing his lyre.
ENTRANCED
Orpheus was said to have charmed
even the rocks and streams with his
music. In this 19th-century painting, he
tames the wild animals with his songs.
the constellations
THE SWAN but its main stars are arranged in ALBIREO 5
the shape of a giant cross, hence Beta (β) Cygni, also known as Albireo, marks
Cygnus its alternative popular name of the the beak of the swan. This double star, with
Northern Cross. its strikingly contrasting colours, is easily
SIZE RANKING 16 far apart that they can be seen separated with a small telescope.
SPECIFIC FEATURES separately with ordinary binoculars,
BRIGHTEST STAR Cygnus’s brightest star, Deneb – if steadily mounted, and they are Cygni, a 4th-magnitude orange
Alpha (α) Cygni – lies in the tail of easy targets for a small telescope.The star, and its wide 5th-magnitude
Deneb (α) 1.2 the swan, or at the top of the cross, brighter star, of magnitude 3.1, is companion, 30 Cygni, which has a
GENITIVE Cygni depending on how the constellation orange, and the fainter star, magnitude noticeable bluish colour when seen
is visualized. Deneb is an immensely 5.1, is blue-green. through binoculars. A 7th-magnitude
ABBREVIATION Cyg luminous supergiant star located more star, again bluish, and even closer to
than 3,000 light-years away, making it A similar colour difference is Omicron-1, can also be seen with
HIGHEST IN SKY AT 10PM the most distant 1st-magnitude star. evident between Omicron-1 (ο1) binoculars or a small telescope.
It forms one corner of the northern Another pair of stars that is easy
August–September Summer Triangle – a familiar sight THE SWAN
in the skies of northern summers
FULLY VISIBLE and southern winters – which is
completed by Vega (in Lyra) and
90˚N–28˚S Altair (in Aquila).
Situated in a rich area of the Milky The beak of the swan (or the foot
Way, Cygnus is one of the most of the cross) is marked by a double
prominent constellations of the star, Beta (β) Cygni, known as
northern sky and contains numerous Albireo. Its two stars are sufficiently
objects of interest.The relatively large
constellation depicts a swan in flight,
THE NIGHT SKY POISED IN FLIGHT 2
Among the stars of Cygnus, it is
comparatively easy to visualize a swan,
with its wings outstretched, as it flies
along the Milky Way.
the constellations
to spot with a small telescope is 61 through binoculars on clear, dark MYTHS AND STORIES
Cygni (see p.248), which consists of nights, but its full majesty becomes
two orange dwarfs of 5th and 6th apparent only on long-exposure LEDA AND THE SWAN
magnitudes that orbit each other photographs or CCD images.The Veil
every 650 years. A large open star Nebula is a diffuse nebula found in The swan represents the disguise adopted by
cluster, M39, covers an area of sky of the wing of the swan. Again, it is best Zeus for an illicit love tryst.The object of his
similar size to the full Moon near the seen on photographs, although the desire is sometimes said to have been a nymph
constellation’s border with Lacerta. brightest part – NGC 6992 – can just called Nemesis or, in a more popular version,
be made out with binoculars or a Queen Leda of Sparta. After her union with
On clear nights, the Milky Way small telescope and becomes more Zeus, Leda is said to have given birth to
appears as a hazy band of light prominent with the addition of filters either one or two eggs, according to
running through Cygnus, divided in to the telescope. Considerably smaller, different versions of the story, from which
two by an intervening cloud of dust but much easier to spot, is the hatched Castor, Pollux, and their sister
known as the Cygnus Rift or the Blinking Planetary (NGC 6826) in Helen of Troy. Pollux and Helen were
Northern Coalsack.The rift the other wing of the swan, with a reputedly the offspring of Zeus, but
continues, via Aquila, into Ophiuchus. Castor was the son of Leda’s
husband, King Tyndareus.
Two large and remarkable nebulae
are found in Cygnus, although neither FAMILY GROUPING
Queen Leda, the twins Castor and Pollux,
is easy to identify.The glowing and the swan are captured in this painting
gas cloud of the North after the original by Leonardo da Vinci.
America Nebula
(NGC 7000),
near Deneb,
can be
glimpsed
OPEN CLUSTER M39 15 blue-green disc similar in size to that
M39 is the larger and brighter of Jupiter. It is popularly known as
of the two Messier clusters the Blinking Planetary because of an
in Cygnus and contains around odd optical effect in which, as the
30 members arranged in a observer looks alternately directly at
triangular shape, with a double it and off to one side, it appears to
star near the centre. It lies 900 blink on and off.
light-years away and is easily
spotted with binoculars. Under Two objects of considerable
good conditions, M39 is visible astrophysical interest in Cygnus are
to the naked eye. beyond the reach of amateur
observers. Cygnus A (see p.314) is a
powerful radio source, the result of
two galaxies in collision millions of
light-years away. Cygnus X-1 (see
p.268), near Eta (η) Cygni, is an
intense X-ray source, thought to be a
black hole orbiting a 9th-magnitude
blue supergiant in our galaxy.
NORTH AMERICA NEBULA 154
In the tail of the swan lies NGC 7000, which
is popularly known as the North America
Nebula, on account of its similarity in shape
to that continent.
VEIL NEBULA 54 THE NIGHT SKY
Splashed across an area wider than six full Moons is the
Veil Nebula, a loop of gas that is the remains of a star that
exploded as a supernova thousands of years ago.
the constellations
ANDROMEDA constellation Pegasus, where it marked field of view and to concentrate the The open star cluster NGC 752
the navel of the horse.The star’s two light.The small companion galaxies, spreads over an area larger than the
Andromeda names – Alpheratz and Sirrah – are M32 and M110, are difficult to see full Moon and can be identified with
both derived from an Arabic term through a small telescope. binoculars, but a small telescope is
SIZE RANKING 19 that means “the horse’s navel”. needed to resolve its individual stars
Gamma (γ) Andromedae, known of 9th magnitude and fainter.
BRIGHTEST STARS SPECIFIC FEATURES also as Almaak or Almach (see p.273),
On a clear night, the farthest it is is a double star of contrasting colours. NGC 7662, which is popularly
Alpheratz (α) 2.1, possible to see with the naked eye It consists of an orange giant star of known as the Blue Snowball, is one
Mirach (β) 2.1 is about 2.5 million light-years, magnitude 2.3 and a fainter blue of the easiest planetary nebulae to
which is the distance to the identify, and it can be found through
GENITIVE Andromeda Galaxy (see companion, and it is easily seen a small telescope.
pp.302–303), a huge spiral of through a small telescope.
Andromedae stars similar to our own galaxy.
ABBREVIATION And Also known as M31, this
galaxy spans several diameters
HIGHEST IN SKY AT 10PM of the full Moon and lies
high in the mid-northern
October–November sky on autumn evenings.
The naked eye sees it as a
FULLY VISIBLE faint patch; it looks
elongated, rather than
90°N–37°S spiral, because it is
tilted at a steep angle
This celebrated constellation of the towards the Earth.
northern skies depicts the daughter of When looking at
the mythical Queen Cassiopeia, who M31 through a
is represented by a neighbouring telescope, low
constellation.The head of the princess magnification
is marked by Alpheratz (or Sirrah ) – must be used to
Alpha (α) Andromedae – which is the give the widest
star at the nearest corner of the
Square of Pegasus, in another adjacent
constellation. Long ago, Alpheratz was
regarded as being shared with the
THE BLUE
SNOWBALL 54
When seen through a small
telescope, NGC 7662 appears
as a bluish disc. Its structure
is brought out only on CCD
images such as this one.
THE ANDROMEDA GALAXY 4 ANDROMEDA
Only the inner parts of M31 are
bright enough to be seen with small MYTHS AND STORIES
instruments. CCD images such as this
bring out the full extent of the spiral HEROIC RESCUE
arms. Below M31 on this image lies
M110, while M32 is on its upper rim. According to Greek mythology,
Andromeda was chained to a rock
THE NIGHT SKY on the seashore and offered as a
sacrifice to a sea monster in
atonement for the boastfulness of
her mother, Queen Cassiopeia.
The Greek hero Perseus, flying
home after slaying Medusa, the
Gorgon, noticed the maiden’s
plight. He responded by swooping
down in his winged sandals and
killing the sea monster. He then
whisked Andromeda to safety and
married her.
DAMSEL IN DISTRESS
The Flemish artist Rubens added the flying
horse Pegasus to his 17th-century depiction of
Andromeda’s dramatic rescue by Perseus from
captivity on the rock.
.
HEAD TO TOE 2
Andromeda is one of the original Greek
constellations. Its brightest stars
represent the princess’s head (α), her
pelvis (β), and her left foot (γ).
the constellations
THE LIZARD to be a peculiar 14th-magnitude THE LIZARD
variable star, has given its name to a
Lacerta class of galaxies with active nuclei
called BL Lac objects or “blazars”.
SIZE RANKING 68
A BL Lac object is a type of quasar
BRIGHTEST STAR that shoots jets of gas from its centre
directly towards the Earth. Because
Alpha (α) 3.8 we see these jets of gas head-on, these
BL Lac objects tend to look star-like.
GENITIVE
Lacertae
ABBREVIATION Lac
HIGHEST IN SKY AT 10PM
September–October
FULLY VISIBLE
90°N–33°S
Lacerta consists of a zigzag of faint
stars in the northern sky, squeezed
between Andromeda and Cygnus like
a lizard between rocks. It is one of the
seven constellations invented by
Johannes Hevelius (see p.368) during
the late 17th century.
This constellation contains
no objects of note for amateur
astronomers, although BL Lacertae
(see p.315), which was once thought
THE TRIANGLE
Triangulum
SIZE RANKING 78
BRIGHTEST STAR
Beta (β) 3.0
GENITIVE Trianguli
ABBREVIATION Tri
HIGHEST IN SKY AT 10PM
November–December
FULLY VISIBLE
90°N–52°S
This small northern constellation is to TRIANGULUM AND MARS 2 THE TRIANGLE THE NIGHT SKY
be found lying between Andromeda This image of the three stars that
and Aries. It consists of little more make up the shape of Triangulum also M33 54
than a triangle of three stars. includes the planet Mars, passing The clouds of pinkish gas in the arms of M33
Triangulum is one of the through neighbouring Pisces. show up in CCD images of this spiral galaxy
constellations known to the ancient in the Local Group. It is presented almost
Greeks, who visualized it as the Nile face-on to the Earth.
delta or the island of Sicily.
SPECIFIC FEATURES
Triangulum contains the third-largest
member of our Local Group of
galaxies, M33 or the Triangulum
Galaxy (see p.301). In physical terms,
M33 is about one-third the size of
the Andromeda Galaxy, or M31 (see
pp.302–303), and is much fainter.
The spiral galaxy M33 appears as a
large pale patch of sky. It is of a
similar size to the full Moon, when
viewed through binoculars or a small
telescope on a dark, clear night.To see
the spiral arms, a large telescope is
needed. M33 looks like a starfish on
long-exposure photographs.
There is little else of note in the
constellation apart from 6 Trianguli.
This yellow star has a magnitude
of 5.2 and has a 7th-magnitude
companion which can be detected
through a small telescope.
THE constellations
THE VICTORIOUS HERO of the pair drops to just one-third its MYTHS AND STORIES
normal value, a change that is readily
Perseus noticeable to the naked eye. Algol’s MEDUSA
brightness returns to normal after
SIZE RANKING 24 another five hours. Predictions of Perseus, the son of Zeus and Danaë, was
Algol’s eclipses can be found in sent to bring back the head of Medusa, the
BRIGHTEST STAR astronomical annuals and magazines. Gorgon, whose evil gaze turned everything
to stone. He was given a bronze shield by
Mirphak (α) 1.8 Rho (ρ) Persei is a variable of a the goddess Athene, a sword of diamond
GENITIVE Persei different kind: it is a red giant that by Hephaestus, and winged sandals by
fluctuates by about 50 per cent in Hermes. Looking only at Medusa’s
ABBREVIATION Per brightness every seven weeks or so. reflection in his shield, Perseus managed
to decapitate the Gorgon.
HIGHEST IN SKY AT 10PM Popularly termed the Double
Cluster, the twin open clusters SUCCESSFUL MISSION
November–December NGC 869 and NGC 884 are one of Perseus proudly displays the severed head
the showpieces of the northern sky. of Medusa, the Gorgon, in this neoclassical
FULLY VISIBLE Each cluster contains hundreds of sculpture by Antonio Canova.
stars of 7th magnitude and fainter, and
90°N–31°S covers an area of sky similar to that of
the full Moon.They lie more than
Perseus is a prominent northern 7,000 light-years away in the Perseus
constellation lying in the Milky Way spiral arm of our galaxy. Both clusters
between Cassiopeia and Auriga. It is are noticeable to the naked eye as a
an original Greek constellation and brighter patch in the Milky Way near
represents Perseus, who was sent to the border with Cassiopeia and can
slay Medusa, the Gorgon. In the sky, be seen well through binoculars or a
Perseus is depicted with his left hand small telescope.
holding the Gorgon’s head, which is
marked by Algol – Beta (β) Persei – a M34 is a scattered open cluster of
famous variable star (see p.272). His several dozen stars near the border
right hand brandishes his sword, with Andromeda. It covers a similar
marked by the twin clusters NGC apparent area to the full Moon and is
869 and NGC 884. easy to spot through binoculars.
SPECIFIC FEATURES ALPHA PERSEI CLUSTER 2
The constellation’s brightest member Mirphak and its surrounding cluster lies
– Mirphak, or Alpha (α) Persei – is of above centre. The Pleiades Cluster is lower
magnitude 1.8. It lies at the centre of right, and Capella, in Auriga, is lower left.
a group of stars known as the Alpha
Persei Cluster or Melotte 20. THE
Scattered over an area of sky that is VICTORIOUS HERO
several times the diameter of the full
Moon, the cluster is an excellent sight
through binoculars.
Algol is an eclipsing binary
consisting of two stars in close
orbit, one much hotter and
brighter than the other.Together
they shine at magnitude 2.1, but
every 69 hours the fainter star
eclipses its companion. Over a
period of five hours, the
combined light
THE NIGHT SKY DOUBLE CLUSTER 15
Of these two star clusters, NGC 869 (left)
appears to be more densely packed. NGC 884
(right) contains some red giant stars, which
its neighbour lacks.
THE RAM THE constellations
Aries LEGENDARY RAM 2
From a crooked line formed by three faint
SIZE RANKING 39 stars, ancient astronomers visualized the
figure of a crouching ram, with its head
BRIGHTEST STAR turned back over its shoulder.
Hamal (α) 2.0
GENITIVE Arietis
ABBREVIATION Ari
HIGHEST IN SKY AT 10PM
November–December
FULLY VISIBLE
90°N–58°S
This not particularly conspicuous EASY DOUBLE 5
constellation of the zodiac is found Gamma (γ) Arietis is
between Pisces and Taurus. Its most readily separable by a
recognizable features are three stars small telescope to reveal
near the border with Pisces: Alpha a pair of white stars, each
(α), Beta (β), and Gamma (γ) Arietis, of 5th magnitude.
of 2nd, 3rd, and 4th magnitudes.
THE RAM
Aries depicts the golden-fleeced
ram of Greek legend (see panel,
below). Over 2,000 years ago, the
vernal equinox – the point at which
the ecliptic crosses the celestial
equator – lay near the border of
Aries and Pisces.The effect of
precession (see p.60) has now
moved the vernal equinox almost
into Aquarius, but it is still called
the first point of Aries.
SPECIFIC FEATURES
Gamma was one of the first stars
discovered to be double, and it
was found by the English scientist
Robert Hooke in 1664, when
telescopes were still quite crude
and it was not realized that
double stars are numerous.To
the naked eye, it appears of 4th
magnitude, but when viewed
through a small telescope it
consists of nearly identical white
stars of magnitudes 4.6 and 4.7.
Lambda (λ) Arietis, of 5th
magnitude, has a companion of
7th magnitude that can be seen
through large binoculars. Pi (π)
Arietis, also of 5th magnitude,
has a very close companion of
8th magnitude.
MYTHS AND STORIES THE NIGHT SKY
THE GOLDEN FLEECE
Aries represents the ram whose golden
fleece hung on a tree in Colchis on the
Black Sea. Jason and the Argonauts
undertook an epic voyage to bring this
fleece back to Greece. Jason was aided
in his task by Medea, who had fallen in
love with him. She was the daughter of
King Aeetes, who owned the fleece.
Medea bewitched the serpent guarding
the fleece so that Jason could steal it.
Taking Medea and the fleece with him,
Jason then sailed away in the Argo.
GOLDEN MOMENT
Watched by an admiring Medea, Jason
removes the glittering fleece from the oak tree
on which it hung at Colchis, in this illustration
by L. du Bois-Reymond.
the constellations
THE BULL is only about one-tenth of a HYADES AND PLEIADES 21
magnitude either side of its average The Hyades (lower left) is the
Taurus value of 0.85 and is barely noticeable. larger of these two dazzling star
Although Aldebaran appears to be clusters; the Pleiades (upper
SIZE RANKING 17 part of the Hyades cluster, it lies 65 dust from the stars’ formation, but it is right) is a tighter bunch that
light-years away – less than half the now recognized as an unrelated cloud appears hazy at first glance –
BRIGHTEST STAR cluster’s distance – and is super- into which the cluster has drifted. good viewing conditions are
imposed only by chance. needed to see all nine named
Aldebaran (α) 0.85 The first object on Charles stars with the naked eye.
GENITIVE Tauri The main stars of the Hyades are Messier’s list of comet-like objects
arranged in a V-shape that is the (see p.69), M1 is the remains of a star filaments of gas that protruded from
ABBREVIATION Tau width of over ten diameters of the full that exploded as a supernova in AD the supernova remnant resembled the
Moon. More than a dozen stars are 1054. It was given its popular name. legs of a crab.The Crab Nebula is
HIGHEST IN SKY AT 10PM visible with the unaided eye, and the Crab Nebula, by the Irish found two diameters of the full Moon
dozens more come into view through astronomer William Parsons (see away from Zeta Tauri.Through a
December–January binoculars. At 150 light-years away, p.305) in 1844, because small telescope, it appears as a faint
the Hyades is the nearest major star he thought the elliptical glow several times larger
FULLY VISIBLE cluster to the Earth. On one arm of than the disc of Jupiter. Large
the Hyades’ V-shape is a wide double THE BULL apertures are needed to make out the
88°N–58°S star,Theta (θ) Tauri. At magnitude level of detail seen by Parsons.
3.4, the brighter of the pair,Theta-1
Taurus is a large and prominent (θ1), is also the brightest member of
northern constellation of the zodiac, the Hyades. Another double star that
and it contains a wealth of objects is easy to spot is Sigma (σ) Tauri,
including the Pleiades and Hyades which has two 5th-magnitude
star clusters (see p.287 and p.286 components, near Aldebaran.The
respectively) and M1, the Crab apex of the Hyades cluster points
Nebula (see pp.266–67). Its stars towards Lambda (λ) Tauri, an
represent the head and forequarters eclipsing binary of the same type as
of a mythical Greek bull.The Hyades Algol (in Perseus). It varies between
cluster is centred on the bull’s face, magnitudes 3.4 and 3.9 in a cycle
while the constellation’s brightest star, lasting just under four days.
Aldebaran – Alpha (α) Tauri (see
p.252) – is its glinting eye. Alnath (or An even brighter star cluster is
Elnath) – Beta (β) Tauri – and Zeta the Pleiades, which hovers over the
(ζ) Tauri mark the tips of the bull’s bull’s shoulders. Although popularly
long horns. Each November, the known as the Seven Sisters, after a
Taurid meteors appear to radiate from group of mythical Greek nymphs
a point south of the Pleiades. (see panel, opposite), the Pleiades
in fact contains nine named stars
SPECIFIC FEATURES – the seven sisters themselves and
Aldebaran is a red giant whose colour their parents, Atlas and Pleione.
is clearly apparent to the naked eye. The brightest member is Alcyone
As with many red giants, it is slightly (see p.273), which is of magnitude
variable in brightness but the amount 2.9 and lies near the centre of the
cluster.The Pleiades covers an area
THE CRAB NEBULA 54 of sky three times the width of the
This supernova reveals the beauty of a full Moon. On long-exposure
massive star’s violent death throes. photographs of the Pleiades, a
Convoluted filaments of gas expand away surrounding haze is visible.This was
from the site of the supernova explosion, once thought to be left-over gas and
which was seen from Earth in AD 1054.
THE PLEIADES
THE HYADES MAGNITUDE KEY
THE NIGHT SKY 0.0–0.9
1.0–1.9
2.0–2.9
3.0–3.9
4.0–4.9
5.0–5.9
6.0–6.9
MYTHS AND STORIES
THE LOST PLEIAD
The popular name for the Pleiades is the Seven
Sisters, although only six stars are easily visible THE NIGHT SKY
to the naked eye.Two myths have arisen to
explain the “missing” Pleiad. One myth says that
the star that shines least brightly is Merope, the
only one of the seven sisters to marry a mortal.
Another story says that it is Electra, who could
RAGING BULL 2 not bear to stay and watch the fall of Troy, the
Taurus, the celestial bull, thrusts his star-
tipped horns into the night air. The bull is city founded by her brother.
said to represent a disguise adopted by
Zeus in a Greek myth. The bright reddish The names of the stars in the WANDERING STAR
“star” seen here on the bull’s back, below cluster do not follow either This 19th-century painting,
the Pleiades, is actually the planet Mars.
of these legends, however, for The Lost Pleiad, depicts the
the faintest named member separation of one of the
Pleiades from her sisters.
is actually Asterope.
the constellations
THE TWINS mark the heads of the twins, while THE ESKIMO NEBULA 54
their feet lie bathed in the Milky Way. The planetary nebula NGC 2392 is
Gemini In mid-December each year, the so-called because it is surrounded by
Geminid meteors radiate from a point a fringe of gas that resembles the
SIZE RANKING 30 in Gemini near Castor. Although Castor and Pollux are fur-lined hood of an Eskimo’s parka.
named after twins, the stars
BRIGHTEST STAR SPECIFIC FEATURES themselves are far from identical. LARGE AND SMALL CLUSTER 15
Castor is a remarkable multiple star. Being an orange giant, Pollux is The large star cluster M35 is visible through
Pollux (β) 1.2 To the naked eye, it appears as a single noticeably warmer-toned than Castor. binoculars; larger telescopes reveal a fainter
GENITIVE Geminorum entity of magnitude 1.6, but through It is also closer to the Earth, lying and more distant cluster, NGC 2158 (bottom
a small telescope with suitably high only 34 light-years away, compared to right), in the same field of view.
ABBREVIATION Gem magnification, it divides into a Castor’s 52 light-years.
sparkling blue-white duo of 2nd and Nebula, or NGC 2392 (see p.255), a
HIGHEST IN SKY AT 10PM 3rd magnitudes.The two stars form a The open star cluster M35 lies at planetary nebula with a bluish disc
genuine binary, with an orbital period the feet of the twins. Under clear similar in size to that of the globe of
January–February of 470 years, which also has a 9th- skies, this cluster can be glimpsed Saturn and visible through a small
magnitude red dwarf companion. with the naked eye, but it is more telescope. Larger telescope apertures
FULLY VISIBLE Although these three stars cannot be easily found with binoculars, through are needed to reveal the nebula’s
divided further visually, each is a which it appears as an elongated, surrounding fringe of gas, reminiscent
90°N–55°S spectroscopic binary, bringing the elliptical patch of starlight spanning of an Eskimo’s parka, that gives NGC
total number of stars in the Castor the same apparent width as the full 2392 its popular name. An alternative
This prominent zodiacal constellation system to six. Moon.When viewed through a small name for this nebula is the Clown-
represents the mythical twins Castor face Nebula.
and Pollux, who were the sons of THE TWINS telescope, its individual stars seem to
Queen Leda of Sparta and the form chains or curved lines.
brothers of Helen of Troy (see Leda Two variable stars of note in
and the Swan, p.351).The constellation Gemini are Zeta (ζ) Geminorum
is easily identifiable within the
northern sky because of its two (see p.282), which is a Cepheid
brightest stars, which are named after variable that ranges between
the twins. Even though it is labelled magnitudes 3.6 and 4.2 every 10.2
Beta (β) Geminorum, Pollux is days, and Eta (η) Geminorum (see
brighter than Castor, or Alpha (α) p.280), which is a red giant whose
Geminorum (see p.272).The two stars brightness can vary anywhere
between magnitudes 3.1 and 3.9.This
constellation also contains the Eskimo
THE NIGHT SKY CELESTIAL TWINS 2
Castor and Pollux, the twins of the
Greek myth, stand side by side in the sky
between Taurus and Cancer. The bright
“star” in the middle of Gemini in this
picture is actually the planet Saturn.
the constellations
THE CRAB small telescope is Zeta (ζ) Cancri. Its still the width of the full Moon in the MYTHS AND STORIES
components, of 5th and 6th magnitude, sky. It lies about 2,600 light-years
Cancer form a binary star with an orbital away – more distant than the Beehive A SMALL VICTORY
period of more than 1,000 years. Cluster, which is 520 light-years away.
SIZE RANKING 31 M67 can be found with binoculars, According to the Greek story, a
The Beehive Cluster (M44) is a but a telescope is needed to resolve crab attacked Hercules during his
BRIGHTEST STAR large open cluster at the the heart of individual stars. At an estimated age of fight with the multi-headed Hydra
Cancer, located between Gamma (γ) around 5 billion years, it is one of the but was crushed underfoot during
Beta (β) 3.5 and Delta (δ) Cancri.The ancient oldest open clusters known – it is also the struggle. Such a minor role
GENITIVE Cancri Greeks could see the cluster as a misty of similar age to Earth. befits this faint constellation.
spot with the unaided eye, but under
ABBREVIATION Cnc modern urban skies it is unlikely to THE BEEHIVE CLUSTER 1 SCUTTLING AWAY
be visible without binoculars.This Also known as the Manger Cluster, M44 is an A small crab can be seen in the foreground of
HIGHEST IN SKY AT 10PM cluster consists of a scattering of stars open cluster located between the two asses this 18th-century engraving, Hercules Fights
of 6th magnitude and fainter. It the Lernean Hydra.
February–March appears to cover an area more than feeding from the manger, Gamma (γ) (centre,
three times wider than the diameter top) and Delta (δ) Cancri (centre bottom).
FULLY VISIBLE of the full Moon, and although it can
be seen through binoculars, it is too
90°N–57°S wide to fit in the field of view of
most telescopes.
Cancer is the faintest of the 12
zodiacal constellations, lying in the The Beehive Cluster’s glory
northern sky between Gemini and overshadows another open cluster,
Leo, and it represents the crab of M67, which is smaller and denser yet
Greek mythology (see panel, right).
Cancer includes the major open star
cluster M44 (see p.286), which is
alternatively known as the Beehive
Cluster, the Manger Cluster, or
Praesepe – which is the Latin for
both “hive” and “manger”. It also
includes the stars Gamma (γ) and
Delta (δ) Cancri, which represent two
donkeys feeding at the manger.These
two stars are sometimes known as
Asellus Borealis and Asellus Australis,
the northern and southern asses.
SPECIFIC FEATURES M67 15
Iota (ι) Cancri is a 4th-magnitude Inferior to M44, but still worthy
yellow giant with a nicely contrasting of note, M67 can be found
7th-magnitude blue-white with binoculars in the region of
companion.The companion is just Cancer south of the ecliptic.
detectable through 10 x 50
binoculars, and it is easy to identify
through a small telescope. Another
double star that can be seen through a
THE CRAB
HIDDEN CRAB 2 THE NIGHT SKY
Cancer is the faintest constellation in
the zodiac, but it contains a major star
cluster, M44, which is just visible in this
photograph as a hazy patch near the
centre of the constellation.
the constellations
THE LITTLE LION SPECIFIC FEATURES THE LITTLE
Unusually, this constellation has no LION
Leo Minor star labelled Alpha.This is due to an
error by the 19th-century English NGC 4565 54
SIZE RANKING 64 astronomer Francis Baily, who Seen edge-on, this
assigned the Greek letters to the spiral galaxy displays
BRIGHTEST STAR constellation’s stars.When doing so, a lane of dark dust
he overlooked assigning a Bayer along its spiral arms
46 Leonis Minoris 3.8 letter to the brightest star, 46 Leonis when viewed through
Minoris, which should have been larger apertures.
GENITIVE recorded as Alpha (α), although he
did label the second-brightest star
Leonis Minoris as Beta (β) Leonis Minoris.
ABBREVIATION LMi
Although Leo Minor contains
HIGHEST IN SKY AT 10PM no objects of interest for users of
binoculars or a small telescope, Beta
March–April (β) is a close double star that can be
separated by a telescope with very
FULLY VISIBLE large aperture. It has a magnitude of
4.2, and its component stars orbit
90°N–48°S each other every 37 years.
This small, insignificant constellation, THE LION CUB 2
adjacent to Leo in the northern sky, Having located the distinctive shape of the
represents a lion cub, although this is Sickle in Leo (top, right), look north of it to
not suggested by the pattern of its find the faint stars of Leo Minor.
stars. It was introduced in the 17th
century by the Polish astronomer
Johannes Hevelius (see p.368).
BERENICE’S HAIR SPECIFIC FEATURES an elliptical patch of
The Coma Star Cluster, also known light through a small
Coma Berenices as Melotte 111, is the constellation’s telescope; it is best
main feature. It comprises several detected with a
SIZE RANKING 42 dozen faint stars, which fan out telescope with an
distinctively for several diameters of aperture of 150mm
BRIGHTEST STAR the Moon southwards from Gamma (6in) or more. A dust
(γ) Comae Berenices.This open cluster, cloud near the galaxy’s
Beta (β) 4.2 which is seen to best advantage nucleus creates the
through binoculars, has been imagined “black eye” effect.
GENITIVE as both the bushy tip of a lion’s tail
and a lock of Berenice’s hair. NGC 4565, another spiral galaxy,
Comae Berenices lies edge-on to the Earth and is more
Coma Berenices contains numerous difficult to spot. It appears long
ABBREVIATION Com galaxies in its southern half. Most of and thin when viewed through a
these are members of the Virgo telescope with 100mm (4in) aperture,
HIGHEST IN SKY AT 10PM Cluster, such as M85, M88, M99, and and a lane of dark dust is revealed in
M100, but two notable exceptions, long-exposure photographs.
April–May M64 (see p.304) and NGC 4565, are
closer to the Earth. THE BLACK EYE GALAXY 54
FULLY VISIBLE The spiral galaxy M64 sports a large, dark
Popularly known as the Black Eye dust cloud near its core, giving it the
90°N–56°S Galaxy, M64 is a spiral galaxy tilted at appearance of a blackened eye.
an angle to the Earth, which is seen as
Coma Berenices represents the
flowing locks of Queen Berenice of BERENICE’S
Egypt, which she cut off as a tribute HAIR
to the gods after the safe return of
her husband, Ptolemy III, from battle
during the 3rd century BC. It is a faint
but interesting northern constellation,
lying between Leo and Boötes. In
the mid-16th century, it was named
as a constellation by the Dutch
cartographer Gerardus Mercator.
Before then, its stars were regarded
as forming the tail of Leo.
THE NIGHT SKY MANE OF HAIR 2
The distinctive splay of the Coma Star
Cluster marks out Coma Berenices in
the night sky. Leo’s hindquarters can
be seen closer to the horizon.
THE LION SPECIFIC FEATURES
Regulus – Alpha (α) Leonis
Leo (see p.249) – lies at the foot of
the Sickle. It is the faintest of the
SIZE RANKING 12 first-magnitude stars, at magnitude
1.4, and its wide companion is of
BRIGHTEST STAR 8th magnitude.
Regulus (α) 1.4 The double star Algieba, or
GENITIVE Leonis Gamma (γ) Leonis, consists of
components of magnitudes 2.2
ABBREVIATION Leo and 3.5. Both stars are orange
giants, and they orbit each other
HIGHEST IN SKY AT 10PM every 600 years or so. A nearby
star – 40 Leonis – is unrelated.
March–April
Zeta (ζ) Leonis is a wide
FULLY VISIBLE triple star, consisting of a 3rd-
magnitude star with a 6th-
82°N–57°S magnitude companion to both
the north and south, which can
The outline stars of Leo really do be seen with binoculars. All
bear a marked resemblance to a three stars are at different
crouching lion, in this large distances from Earth and, hence,
constellation of the zodiac, located they are unrelated.
just north of the celestial equator. It
is one of the easiest constellations to A pair of spiral galaxies, M65
recognize.The pattern of six stars that and M66, can be glimpsed with a
marks the lion’s head and chest is small telescope beneath the hind
known as the Sickle and is shaped like quarters of Leo. A fainter pair of
a reversed question mark or a hook. spirals, M95 and M96, lie under the
The Leonid meteors radiate from the lion’s body, as does an elliptical galaxy,
region of the Sickle every November M105, about one degree away.
(see pp.220–21).
THE LION
ALGIEBA 5 LEO TRIPLET 54
This beautiful pair of golden-coloured A trio of galaxies lies near Theta
orange giants is clearly visible through (θ) Leonis: M65 (lower right);
small telescopes. M66 (lower left); and the edge-on
spiral NGC 3628 (top). Although
NGC 3628 appears the largest on
photographs, it is less bright than
the others and is difficult to see
through small telescopes.
THE BIG CAT 2 MYTHS AND STORIES THE NIGHT SKY
The crouching lion is a distinctive sight
in the night sky. The pattern of its stars HERCULES AND THE LION
is disturbed here by the presence of
Jupiter under the lion’s body. Leo represents the mythical lion that lived in a
cave near the Greek town of Nemea, terrorizing
the area and emerging to attack and devour local
inhabitants. As the first of the 12 labours in his
quest for immortality, Hercules was sent by his
cousin Eurystheus to kill the lion. Finding
that the creature’s hide was impervious to
his arrows, Hercules instead wrestled and
strangled the beast. He then used the lion’s
own razor-sharp claws to cut off its pelt,
which he wore victoriously as a cloak.
THE HERO AND THE BEAST
Hercules grapples with the Nemean Lion in a
sculpture by the 16th-century Flemish artist
Jean de Boulogne, or Giambologna.
the constellations
THE VIRGIN (2.4in) after 2012. For the rest of the MYTHS AND STORIES
21st century, it will be possible to
Virgo split Porrima with a small-aperture THE VIRGIN GODDESS
telescope. Both of Porrima’s stars are
SIZE RANKING 2 of magnitude 3.5, and their orbital Virgo is usually identified as Dike,
period is 169 years. the Greek goddess of justice, who
BRIGHTEST STAR abandoned the Earth and flew up to
In the upper part of Virgo’s body heaven when human behaviour
Spica (α) 1.0 lie the numerous galaxies of the deteriorated. Neighbouring Libra
GENITIVE Virginis Virgo Cluster. None is easy to see represents her scales of justice.Virgo
with a small instrument.The brightest is also visualized as Demeter, the
ABBREVIATION Vir members are giant ellipticals, notably corn goddess, who holds an ear of
M49, M60 (see p.307), M84, M86, wheat, which is represented by the
HIGHEST IN SKY AT 10PM and M87 (see p.313). M87 is a strong constellation’s brightest star, Spica.
radio and X-ray source also known as
April–June Virgo A. Long-exposure photographs BOUNTIFUL OFFERINGS
show it is ejecting a jet of gas, like Demeter presented Triptolemus, a prince of Eleusis,
FULLY VISIBLE certain quasars. with a chariot drawn by winged dragons and grains
of wheat to sow crops wherever he travelled.
67°N–75°S The Sombrero Galaxy (see p.306),
or M104, is Virgo’s best-known
Virgo straddles the celestial equator, galaxy.This spiral is about two-thirds
between Leo and Libra. It is the as far away as the Virgo Cluster. It is
largest constellation of the zodiac, and oriented almost edge-on to the Earth,
the second-largest overall.The so that a dark lane of dust in the
constellation depicts a Greek virgin galaxy’s plane crosses its central bulge.
goddess (see panel, right).Virgo The bulge may be all that can be seen
contains the Virgo Cluster (see p.319), through a small telescope; the dust
the nearest large cluster of galaxies lane is only revealed
to Earth, which is some 50 million when seen through
light-years away and which extends a large-aperture
over the border of Virgo into Coma telescope or on long-
Berenices.The Sun is in Virgo during exposure photographs.
the September equinox each year.
The brightest quasar
SPECIFIC FEATURES in the sky, 3C 273
Porrima, or Gamma (γ) Virginis (see (see p.315), also lies
p.249), is a binary star in which the in the bowl of Virgo.
effects of orbital motion will be seen However, it is much
in forthcoming years. Having been more distant than the
closest together in 2005, when a Virgo Cluster.Through
telescope with a 250mm (10in) most telescopes, it
aperture was needed to separate appears as nothing more
Porrima’s components, the two stars than a 13th-magnitude star.
are now moving further apart and Only professional equipment
hence are coming within range of a will reveal it as the centre
smaller telescope.They will become of an active galaxy, which
divisible with a telescope of 100mm is some 2,000 million light-
(4in) aperture by 2010 and of 60mm years away from Earth.
THE CORN GODDESS 2 THE VIRGIN
Spica (bottom, left), is one of the 20
brightest stars in the sky. Its name is Latin
for “ear of wheat”, and it marks the bounty
that the Virgin holds in her left hand.
THE NIGHT SKY THE SOMBRERO GALAXY 5
The Sombrero Galaxy (M104) is a spiral
galaxy with a large central bulge, seen
almost edge-on, and resembling a Mexican
hat. It lies about 30 million light-years away.
M87 54
Through a small
telescope, the giant
elliptical galaxy M87
appears as a rounded
glow, but photographs
and CCD images
reveal the jet of gas
that is being expelled
from its highly active
nucleus. Here, the jet
is just visible near the
top right of the core.
the constellations
THE SCALES Zubeneschamali (“the northern the brighter star. Mu (μ) Librae, with Delta (δ) Librae is an eclipsing
claw”) or Beta (β) Librae, which components of 6th and 7th variable. Every two days eight hours,
Libra shows a greenish tinge when viewed magnitude, is a more difficult pair to it rises and falls between 5th and 6th
through binoculars or a telescope. separate; a telescope with 75mm (3in) magnitudes.This change can be
SIZE RANKING 29 This highly unusual colouring is due, aperture is needed. readily followed with binoculars.
presumably, to the chemical
BRIGHTEST STAR composition of Zubeneschamali’s THE SCALES
outer layers.
Beta (β) 2.0
GENITIVE Librae In the heart of the constellation
lies Iota (ι) Librae, a double with stars
ABBREVIATION Lib of 5th and 6th magnitudes which
can be viewed through binoculars. A
HIGHEST IN SKY AT 10PM small telescope will reveal the closer
9th-magnitude companion of
May–June
FULLY VISIBLE
60°N–90°S
This constellation of the zodiac lies LIBRA’S STARS 2
just south of the celestial equator Now regarded as the scales of
between Virgo and Scorpius. justice, the stars of Libra were once
Originally, the ancient Greeks visualized as the claws of the
visualized the constellation as the adjacent scorpion, Scorpius.
claws of the neighbouring Scorpius,
which is why Libra’s brightest stars
have names that mean the northern
claw and the southern claw. Libra’s
present-day identification as Virgo’s
scales of justice became more
common in Roman times.
SPECIFIC FEATURES
Zubenelgenubi (Arabic for “the
southern claw”) or Alpha (α) Librae
is a wide double star of 3rd and 5th
magnitudes and is easily divisible with
binoculars or even sharp, unaided
eyesight.To the north of this pair is
the constellation’s brightest star,
THE NORTHERN CROWN Corona Borealis has three double stars components of 5th and 6th MYTHS AND STORIES
magnitudes – an attractive sight when
Corona Borealis of note for small-instrument users, seen through a small telescope – PRINCESS ARIADNE
while Sigma (σ) Coronae Borealis is a
SIZE RANKING 73 although none is particularly bright. yellow pair with components of 6th Ariadne, daughter of King Minos
Nu (ν) Coronae Borealis is a pair of and 7th magnitudes, which can also of Crete, helped Theseus slay the
BRIGHTEST STAR 5th-magnitude red giants divisible be split with a small telescope. Minotaur, a gruesome creature that
with binoculars. Zeta (ζ) Coronae was half-bull, half-human.Theseus
Alphekka or Gemma Borealis is a blue-white pair, with sailed off with Ariadne to the
(α) 2.2 island of Naxos, where he then
abandoned her.The god Dionysus
GENITIVE looked down on the princess and
was overcome. At their wedding,
Coronae Borealis Ariadne wore a jewel-studded
crown, which Dionysus threw into
ABBREVIATION CrB the sky, where the crown’s jewels
were changed into stars.
HIGHEST IN SKY AT 10PM
CROWNING GLORY
June Dionysus, known as Bacchus by the Romans,
holds Ariadne’s jewelled crown, in this
FULLY VISIBLE painting by the 17th-century French artist
Eustache Le Sueur.
90˚N–50˚S
THE
NORTHERN
CROWN
Corona Borealis is a small but THE NIGHT SKY
distinctive constellation in the
northern sky, between Boötes and
Hercules, consisting of a horseshoe
shape of seven stars. It is one of the
original Greek constellations and
represents the crown worn by
Princess Ariadne (see panel, right).
SPECIFIC FEATURES CROWN OF STARS 2
The arc of the northern crown Like a celestial tiara, the seven
contains the remarkable variable main stars of Corona Borealis
star R Coronae Borealis (see form a distinctive arc between
p.283), a yellow supergiant Boötes and Hercules.
normally of 6th magnitude, which
shows sudden dips in brightness.
These fades, which are due to a
build-up of sooty particles in its
atmosphere, occur every few years
and can last for months.
the constellations
THE SERPENT about twice the size of M16. It is Delta (δ) Serpentis, near the
situated in Serpens Cauda near the serpent’s head, is a binary with
Serpens tip of the serpent’s tail. components of 4th and 5th
magnitudes. It is divisible using
SIZE RANKING 23 Close to the border with Virgo lies high powers of magnification
M5, which is about 25,000 light-years on a small telescope.
BRIGHTEST STAR away. Its condensed centre appears as
a faint area about half the size of the Theta (θ) Serpentis, near
Unukalhai (α) 2.6 full Moon, when viewed with the serpent’s tail, is a pair of
binoculars, while the curving chains white stars that are easily split
GENITIVE of stars in its outskirts are revealed through a small telescope.This
only through a telescope with an wide double star has components
Serpentis aperture of 100mm (4in) or more. of magnitude 4.6 and 5.0.
ABBREVIATION Ser THE SERPENT
HIGHEST IN SKY AT 10PM
June–August
FULLY VISIBLE
74°N–64°S
Although counted as a single
constellation, Serpens is in fact split
into two separate areas, and is thus
unique. It is one of the original
48 Greek constellations and straddles
the celestial equator. Serpens represents
a huge snake coiled around Ophiuchus,
who holds the head (Serpens Caput)
in his left hand and the tail (Serpens
Cauda) in his right. In Greek
mythology, snakes were a symbol of
rebirth, because of the fact that they
shed their skins. Ophiuchus represents
the great healer Asclepius, who was
reputedly able to revive the dead
(see panel, opposite).
SPECIFIC FEATURES M5 15
The Eagle Nebula (see pp.242–43) in This is one of the finest
Serpens Cauda was made world- globular clusters in northern
famous by a spectacular Hubble Space skies. M5 is noticeably
Telescope picture of dark columns of elliptical in shape when
dust embedded within its glowing viewed through a telescope.
gas. Unfortunately, the dust columns
show up only through a telescope of
large aperture and on long-exposure
photographs such as those from the
Hubble Space Telescope.
The Eagle Nebula contains a star
cluster, M16, which can be spotted
readily through binoculars or a small
telescope. It appears as a hazy patch
covering an area of sky that is similar
in size to the full Moon. Another
open cluster that is visible through
binoculars is IC 4756, which appears
THE NIGHT SKY THE EAGLE NEBULA 543 SERPENTINE STARS 2
This image was captured by a professional The upper part of the snake (above,
four-metre telescope. It can only be seen well right) contains Unukalhai (α),
with telescopes of large aperture. which derives its name from the
Arabic for “the serpent’s neck”.
THE SERPENT HOLDER globular clusters, although none is THE SERPENT HOLDER BARNARD’S STAR MOVEMENT MAGNITUDE KEY
particularly prominent. M10 and M12
Ophiuchus (see p.289) are both near the centre of INTRICATE NEBULOSITY 4
the constellation and detectable Complex nebulosity extends from
SIZE RANKING 11 through binoculars on a clear night. the area around Rho (ρ) Ophiuchi
Better sights for binoculars are two (at the top of the image below),
BRIGHTEST STAR large and scattered open clusters, southwards to Antares (bottom).
NGC 6633 and IC 4665.
Rasalhague (α) 2.1
An outstanding multiple star is
GENITIVE Rho (ρ) Ophiuchi, lying near Antares
(in neighbouring Scorpius).This 5th-
Ophiuchi magnitude star has a 7th-magnitude
companion either side of it, and these
ABBREVIATION Oph are best viewed through binoculars.
Another 6th-magnitude companion
HIGHEST IN SKY AT 10PM that is much closer to the central star
can be identified through a small
June–July telescope using high magnification.
The complex nebulosity in this area,
FULLY VISIBLE including around Antares, is revealed
only in long-exposure photographs.
59°N–75°S
The beautiful double star
This large constellation straddling 70 Ophiuchi consists of yellow
the celestial equator depicts a man and orange dwarfs, with
holding a snake.The head of components of 4th and
Ophiuchus adjoins Hercules in the 6th magnitudes, while the
north while his feet rest on Scorpius double star 36 Ophiuchi is
in the south.The Sun passes through a pair of orange dwarfs
Ophiuchus in the first half of with components of
December, but despite this the 5th magnitude.
constellation is not regarded as a true
member of the zodiac. Barnard’s Star is the most
celebrated star in Ophiuchus and is
Ophiuchus was the site of the last the second-closest star to the Sun.
supernova explosion seen in our Even though this red dwarf is a mere
Galaxy, which appeared in 1604. It far 5.9 light-years away, its light output is
outshone all other stars and is known so feeble that it appears as only
as Kepler’s Star (see p.269) after magnitude 9.5, and it is too faint to
Johannes Kepler who wrote about it see without a telescope. Barnard’s Star
in De stella nova (see p.64). is moving so quickly relative to the
background stars that its change in
SPECIFIC FEATURES position is noticeable over a matter of
Lying on the edge of the Milky Way only a few years (see chart, right).
in the direction of the centre of our
Galaxy, Ophiuchus contains numerous
star clusters. Messier catalogued seven
MYTHS AND STORIES
ASCLEPIUS
M10 15 Ophiuchus is identified with THE NIGHT SKY
The large globular Asclepius, the Greek god of
cluster M10 is some medicine who reputedly had the
14,000 light-years power to revive the dead. Hades,
away. Like its god of the Underworld, feared that
neighbour M12, this ability endangered his trade in
it is detectable dead souls and asked Zeus to strike
through binoculars Asclepius down. Zeus then placed
on a clear night. the great healer among the stars.
RESTORATIVE POWERS
Asclepius is watched as he heals a female
patient, in this 5th-century BC marble relief
from Piraeus, Greece.
SNAKE MAN 2
Ophiuchus represents a man encoiled by a
huge snake, the constellation Serpens. The
ecliptic runs through Ophiuchus, and planets
can be seen within its borders.
the constellations
THE SHIELD
Scutum
SIZE RANKING 84
BRIGHTEST STAR
Alpha (α) 3.8
GENITIVE Scuti
ABBREVIATION Sct
HIGHEST IN SKY AT 10PM
July–August
FULLY VISIBLE
74°N–90°S
This minor constellation is situated in stars form a fan THE SHIELD
a rich area of the Milky Way, between
Aquila and Sagittarius, south of the shape, like a flock
celestial equator. It was introduced by
Johannes Hevelius (see p.368) in the of ducks in flight, when seen
late 17th century. He gave it the
name Scutum Sobiescianum, meaning through a small telescope. Near the
Sobieski’s Shield, to honour his
patron, King John Sobieski of Poland. apex of the fan is an 8th-magnitude
SPECIFIC FEATURES red giant.The Wild Duck Cluster is
Delta (δ) Scuti is the prototype of a
class of variable star that pulsates in in an area of the constellation that is
size every few hours, changing
brightness by only a few tenths of a known as the Scutum Star Cloud.
magnitude. Delta itself varies between
magnitude 4.6 and 4.8 in less than This rich star field is located just
five hours, but the change is only
detectable with sensitive instruments. south of Beta (β) Scuti.
Far more obvious is R Scuti, an
orange supergiant that rises and falls WILD DUCKS 15
between magnitudes 4.2 and 8.6 in Seen through a small
a 20-week cycle. telescope, M11 looks
like the V-shaped flight
Near R Scuti is the beautiful Wild pattern of wildfowl. This
Duck Cluster (M11), which appears effect is less apparent
as a smudgy glow half the apparent on photographs.
width of the full Moon when viewed
through binoculars.This open cluster SOBIESKI’S SHIELD 2
gained its popular name because its Scutum has no bright stars of its own,
but it lies in an area of the Milky
SCUTUM STAR CLOUD 21 Way, between Aquila and Sagittarius,
One of the brightest parts of the Milky that is particularly rich with stars.
Way lies in Scutum and is known as the
Scutum Star Cloud. The bright spot at
centre left is the Wild Duck Cluster.
THE ARROW SPECIFIC FEATURES ARROW IN FLIGHT 2
There is little of note in Sagitta for The small arrow Sagitta flies over the
Sagitta users of small instruments. Zeta (ζ) stars of Aquila, the eagle, and towards
Sagittae is a 5th-magnitude star with Delphinus, the dolphin.
SIZE RANKING 86 a 9th-magnitude companion that is
visible in a small telescope, but it is THE ARROW
BRIGHTEST STAR not a particularly impressive double.
THE NIGHT SKY S Sagittae is a Cepheid variable that
Gamma (γ) 3.5 halves in brightness every 8.4 days
GENITIVE Sagittae before recovering again, as it swings
between magnitudes 5.2 and 6.0.
ABBREVIATION Sge
Midway along the shaft of the
HIGHEST IN SKY AT 10PM arrow is M71, a modest globular
cluster detectable with
August binoculars but better
seen through a
FULLY VISIBLE telescope. M71 lacks the
central condensation
90°N–69°S typical of most
globulars and instead
Sagitta was known to the ancient looks more like a dense
Greeks, who believed it represented open cluster.
an arrow shot by either Apollo,
Hercules, or Eros. It is the third- WZ Sagittae is a
smallest constellation, lying in the dwarf nova variable
Milky Way between Vulpecula and (see Novae, p.278). It is
Aquila in the northern sky. It is faint rarely in outburst.
and easily overlooked.
the constellations
THE EAGLE Altair is flanked by 4th-magnitude MYTHS AND STORIES
Alshain, or Beta (β) Aquilae, and 3rd-
Aquila magnitude Tarazed, or Gamma (γ) WINGED CARRIERS
Aquilae, which form a distinctive trio.
SIZE RANKING 22 The eagle has at least two identifications in
SPECIFIC FEATURES Greek mythology. It was the bird that
BRIGHTEST STAR Aquila’s main feature of interest is Eta carried the thunderbolts for the god Zeus,
(η) Aquilae (see p.278), which is one and in one myth Zeus sent an eagle, or
Altair (α) 0.8 of the brightest Cepheid variables. Eta took the form of an eagle, to carry the
GENITIVE Aquilae ranges between magnitudes 3.5 and shepherd boy Ganymede up to
4.4 on a cycle of 7.2 days. As with all Mount Olympus, where he
ABBREVIATION Aql members of this class, it is a brilliant was made a servant of the
supergiant. Its distance is estimated at gods. Zeus had spied the boy
HIGHEST IN SKY AT 10PM 1,200 light-years. tending sheep in a field and
had become infatuated with
July–August The constellation also has a couple him. Ganymede is represented
of faint double stars that can readily by neighbouring Aquarius.
FULLY VISIBLE be split with a small telescope: 15
Aquilae, with stars of 5th and 7th ON EAGLE’S WINGS
78°N–71°S magnitudes; and 57 Aquilae, with two The beautiful youth Ganymede is carried
6th-magnitude components. aloft by an eagle in Peter Paul Rubens’s 17th-
Aquila depicts an eagle in flight (see century painting The Abduction of Ganymede.
panel, right). It lies on the celestial
equator in a rich area of the Milky STELLAR TRIO 2
Way near Cygnus, Scutum, and Altair, the constellation’s brightest star,
Sagittarius, yet there are no deep-sky is flanked by 3rd-magnitude Tarazed
objects of particular note within it. (top), which has a noticeably orange
Aquila’s brightest star, Altair or Alpha colour, and 4th-magnitude
(α) Aquilae (see p.248), forms one Alshain (bottom), forming
corner of the northern Summer an attractive
Triangle of stars, completed by Vega stellar trio.
(in Lyra) and Deneb (in Cygnus).
THE HOOK 21 THE EAGLE
This easily recognizable group of stars in
southern Aquila includes Lambda (λ)
Aquilae (centre left) and branches into
neighbouring Scutum.
SWOOPING ACROSS THE SKIES 2 THE NIGHT SKY
The eagle swoops across the evening skies
in the second half of the year. Its main star,
Altair, is the most southerly of those that
form the northern Summer Triangle. Aquila
points towards the stars of Capricornus.
THE CONSTELLATIONS
THE FOX THE FOX the hook. All the stars are unrelated, size of the full Moon, when viewed
however, and so do not form a true through binoculars. Its twin-lobed or
Vulpecula named Vulpecula cum Anser (the cluster.The Coathanger’s shape is hourglass shape is revealed only with
fox with the goose). Its name has therefore the delightful product of a larger instruments and on long-
SIZE RANKING 55 since been simplified to Vulpecula. chance alignment. exposure photographs. It is about
Despite its relative obscurity, it 1,000 light-years away. CCD images
BRIGHTEST STAR contains two unmissable objects Popularly known as the Dumbbell and photographs show a variety of
for binocular users. Nebula, M27 is the easiest planetary colours, but visually the Dumbbell
Alpha (α) 4.4 nebula to spot in the sky. It appears as appears grey-green.
GENITIVE Vulpeculae SPECIFIC FEATURES a rounded patch, about one-third the
ABBREVIATION Vul The brightest star in the
constellation, Alpha (α)
HIGHEST IN SKY AT 10PM Vulpeculae, is a 4th-magnitude
red giant with a 6th-magnitude
August–September orange star nearby, which is visible
with binoculars.The two lie at
FULLY VISIBLE different distances and are unrelated.
90°N–61°S Brocchi’s Cluster is one of the
binocular treasures of the sky.This
This small, faint northern grouping of ten stars, with
constellation lies in the Milky Way components ranging from 5th to 7th
south of Cygnus.When it was first magnitude, is better known as the
introduced in the late 17th century Coathanger because of its shape: a
by the Polish astronomer Johannes line of six stars forms the bar of the
Hevelius (see panel, below), it was hanger while the remaining four are
THE COATHANGER 1
Perhaps the most charming of all star
clusters is Brocchi’s Cluster, also known as
the Coathanger. This group of stars, easily
visible through binoculars, appears to mark
out the shape of a simple coathanger.
THE DUMBBELL NEBULA 154 JOHANNES HEVELIUS
Reputedly the easiest planetary nebula
to spot, M27 can be found with Johannes Hevelius (1611-87) was
binoculars on dark nights. A telescope born and worked in the town of
is needed to make out the twin lobes Danzig, Germany (now Gdansk,
that give rise to its popular name. Poland), where he established an
observatory equipped with the
finest instruments of his time.
Among his legacies was a star
catalogue and atlas, published
posthumously by his assistant and
second wife, Elizabeth, introducing
seven new constellations and filling
the gaps in the northern skies.
THE NIGHT SKY FOX IN THE MILKY WAY 2 JOINT EFFORT
Vulpecula is a shapeless constellation Johannes Hevelius and his wife Elizabeth
sandwiched between the more easily measured star positions with a large sextant.
recognizable pattern of Sagitta, the This instrument is commemorated in one of the
arrow, at left of this picture, and the constellations Hevelius invented, Sextans.
head of the swan, Cygnus.
THE DOLPHIN GAMMA DELPHINI 5 THE CONSTELLATIONS
Gamma (γ) Delphini is an attractive double
Delphinus star. Although both the component stars are THE PLAYFUL DOLPHIN 2
usually described as yellow, some observers The kite-shaped Delphinus, on the
SIZE RANKING 69 see the fainter star as bluish. edge of the Milky Way near Cygnus,
brings to mind a dolphin jumping
BRIGHTEST STAR stars: Sualocin (α), Rotanev (β), and from ocean waters.
Gamma (γ) and Delta (δ) Delphini.
Rotanev (β) 3.6 Who applied the name Job’s Coffin, THE HORSE’S HEAD 2
GENITIVE Delphini and when, is not known. Equuleus consists of a small area of
ABBREVIATION Del faint stars wedged between Pegasus
and Delphinus and is easily overlooked.
HIGHEST IN SKY AT 10PM
August–September
FULLY VISIBLE
90°N–69°S
This small but distinctive constellation SPECIFIC FEATURES
is situated between Aquila and Gamma (γ) Delphini is normally
Pegasus. According to Greek myth, described as an attractive orange-
Delphinus represents the dolphin that yellow double star. Its components
saved the poet and musician Arion are of 4th and 5th
from drowning after he leapt into the magnitudes, and they
sea to escape robbers onboard a ship. are easily separated by
Alternatively, the constellation is said a small telescope.
to depict one of the dolphins sent by
Poseidon to bring the sea nymph The fainter and
Amphitrite to him to marry. It is one closer double star
of the constellations listed by the Struve 2725, which
astronomer Ptolemy (see p.85). has components
of 7th and 8th
The whole constellation was once magnitudes, can also
popularly known as Job’s Coffin, be seen through a
presumably because of the box-like small telescope and is
shape of its area, although sometimes visible in the same
this name is restricted to the diamond field of view as
asterism formed by the four brightest Gamma (γ) Delphini.
NICCOLÒ CACCIATORE THE DOLPHIN
Alpha (α) and Beta (β) Delphini bear the unusual
names Sualocin and Rotanev.When reversed,
these names spell Nicolaus Venator.This is the
Latinized name of Niccolò Cacciatore
(1780–1841), an Italian astronomer who was
assistant to Giuseppe Piazzi, the director of the
Palermo Observatory, Sicily. Cacciatore defied
convention by surreptitiously naming two stars
after himself in the Palermo star catalogue of
1814. No one realized what he had done
until much later, by which time the star
names had become established.
THE FOAL been added to the sky by the
Greek astronomer Ptolemy (see
Equuleus p.85) in his 2nd-century AD
compendium of the original
SIZE RANKING 87 Greek constellations. THE NIGHT SKY
BRIGHTEST STAR SPECIFIC FEATURES
Gamma (γ) Equulei is a wide
Alpha (α) 3.9 double star, with components of
GENITIVE Equulei 5th and 6th magnitudes and is
easily separated with binoculars.
ABBREVIATION Equ Its two stars are unrelated.The
5th-magnitude double star 1
HIGHEST IN SKY AT 10PM Equulei – labelled as Epsilon (ε)
Equulei on some maps – has a
September 7th-magnitude companion,
which can be seen through a
FULLY VISIBLE small telescope, and a fainter
true companion, which can be
90°N–77°S seen only through instruments
with larger apertures. Other than
The second-smallest constellation in these two double stars, there is THE FOAL
the sky represents the head of a young nothing of note in Equuleus for users
horse, or foal, and lies next to the of binoculars or small telescopes.
larger celestial horse, Pegasus. No
myths or legends are associated with
Equuleus, which is thought to have
the constellations THE GREAT SQUARE 2
The most distinctive feature of this
THE WINGED HORSE constellation is the Great Square
of Pegasus, which forms the
Pegasus horse’s body.
SIZE RANKING 7
BRIGHTEST STARS
Beta (β) 2.4,
Epsilon (ε) 2.4
GENITIVE Pegasi
ABBREVIATION Peg
HIGHEST IN SKY AT 10PM
September–October
FULLY VISIBLE
90°N–53°S
Pegasus lies north of the zodiacal
constellations Aquarius and Pisces, in
low northern declinations, and it
adjoins Andromeda. It was one of the
original 48 Greek constellations.
Pegasus represents the flying horse
ridden by the hero Bellerophon,
although he is sometimes wrongly
identified as the steed of Perseus (see
panel, below). Although only the
forequarters of the horse are indicated
by stars, the constellation is still the
seventh-largest in the sky.
SPECIFIC FEATURES
The Great Square of Pegasus is
formed by the stars Alpha (α), Beta
(β), and Gamma (γ) Pegasi, plus Alpha
(α) Andromedae. Long ago, the fourth
star of the Square was also known as
Delta (δ) Pegasi and was shared with
THE NIGHT SKY Andromeda, but now it is MYTHS AND STORIES
exclusively Andromeda’s. A line
of more than 30 full Moons BELLEROPHON
would fit into the Square, yet
AND PEGASUS
for such a large area it is
surprisingly devoid of stars – its Pegasus the winged horse was born
brightest star being Upsilon from the body of Medusa, the
(υ) Pegasi, of magnitude 4.4. Gorgon, when she was decapitated
Therefore, when the Great by Perseus. He flew to Mount
Helicon, home of the Muses,
Square is viewed through where he stamped on the ground
polluted skies, it may seem and brought forth a spring called
completely empty. Hippocrene, the horse’s fountain.
With the aid of a golden bridle
The constellation’s two from Athena, the hero Bellerophon
brightest stars are Beta, a red tamed Pegasus, and rode the horse
giant that varies between on his successful mission to kill the
magnitudes 2.3 and 2.7, and fire-breathing monster Chimaera.
Epsilon (ε) Pegasi, a yellow Bellerophon later attempted to
star of magnitude 2.4 with a ride Pegasus up to Olympus, to
wide 8th-magnitude join the gods, but he fell off. The
companion that can be seen horse arrived safely.
through a small telescope.
TAKING FLIGHT
Not far from Epsilon lies Pegasus beats his wings, as though attempting
the globular cluster M15 to ascend to the skies, in this statue in
(see p.289), which is one of Powerscourt Gardens, Dublin, Ireland.
the finest such objects in
THE WINGED HORSE M15 15 northern skies. It is just at
A telescope with the limit of naked-eye
150mm (6in) aperture visibility when viewed
resolves this globular through clear skies.
cluster into individual
stars. It is over 30,000 Just outside the Great
light-years away. Square of Pegasus is a 5th-magnitude
star called 51 Pegasi, which was the
first star beyond the Sun confirmed to
have a planet in orbit around it.This
planet was discovered in 1995, and its
mass is about half that of Jupiter.
THE WATER CARRIER
Aquarius
SIZE RANKING 10
BRIGHTEST STARS
Sadalmelik (α) 2.9,
Sadalsuud (β) 2.9
GENITIVE
Aquarii
ABBREVIATION Aqr
HIGHEST IN SKY AT 10PM
June–July
FULLY VISIBLE
65°N–86°S
This large constellation of the zodiac SPECIFIC FEATURES in apparent size, at almost half the THE WATER CARRIER
is visualized as a youth (or, sometimes, Zeta – the star at the centre of the diameter of the full Moon. However,
an older man) pouring water from a Water Jar group – is a close binary because its light is spread over such a THE HELIX NEBULA 154
jar. It is is found between Capricornus of 4th-magnitude stars just at the large area, the Helix Nebula can be NGC 7293 is visible as a pale rounded patch
and Pisces, near the celestial equator. limit of resolution with a telescope identified only when skies are clear through binoculars under dark skies, but its
The stars Gamma (γ), Zeta (ζ), Eta of 60mm (2.4in) aperture. Located and dark.Visually, this nebula appears detailed structure and approximate colours
(η), and Pi (π) Aquarii form a Y- near the border with Equuleus, the as a pale grey patch, showing none are brought out in CCD images such as this.
shaped grouping that makes up globular cluster M2 appears as a fuzzy of the beautiful colours captured
the Water Jar, from which a stream star when viewed through binoculars on photographs.
of stars represents water flowing or a small telescope.
towards Piscis Austrinus. In early The second planetary nebula
May each year, the Eta Aquarid Aquarius contains two of the best- – the Saturn Nebula (NGC 7009) –
meteor shower radiates from the known planetary nebulae in the sky. is easier to spot, appearing to be of
area of the water jar. The Helix Nebula (NGC 7293; see similar size to the disc of Saturn when
p.253) is reckoned to be the closest viewed with a small telescope. Its faint
In Greek myths and stories, planetary nebula to the Earth, being extensions on either side, rather like
Aquarius represents Ganymede – a some 300 light-years away. It is the rings of Saturn, give rise to the
beautiful shepherd boy to whom the therefore one of the largest nebulae object’s popular name.
god Zeus took a fancy. Zeus
dispatched his eagle (or, in some
stories, turned himself into an eagle)
to carry Ganymede up to Mount
Olympus, where he became a waiter
to the gods.The Eagle is represented
by neighbouring Aquila.
THE SATURN NEBULA 54
NGC 7009’s resemblance to the ringed planet
Saturn is most evident when it is viewed
through a large telescope or on a CCD image.
POURING WATER 2 THE NIGHT SKY
The cascade of stars that represent
the flow of water from Aquarius’s
jar is to the left of this image. The
distinctive Water Jar is centre, top.
THE CONSTELLATIONS
THE FISHES Alrescha (α) is a close pair of stars of A beautiful face-on spiral galaxy,
4th and 5th magnitudes that can be M74, lies just over two diameters of
Pisces separated with a telescope with an the Moon from the constellation’s
aperture of 100mm (4in).These two brightest star, Eta (η) Piscium. It
SIZE RANKING 14 stars form a true binary with an appears as a round, bright glow
orbital period of more than 900 years. through a small telescope; the spiral
BRIGHTEST STAR Zeta (ζ) and Psi-1 (ψ1) Piscium are arms only show up well through a
two more doubles that can be divided telescope with larger aperture and on
Eta (η) 3.6 with a small telescope. long-exposure photographs.
GENITIVE THE CIRCLET 21
The body of the southerly
Piscium fish is marked by a ring of
stars called the Circlet.
ABBREVIATION Psc One of the stars, TX
Piscium, is a red giant of
HIGHEST IN SKY AT 10PM variable brightness, which
appears noticeably orange
October–November through binoculars.
FULLY VISIBLE DIVERGENCE 2
Pisces represents a pair of
83°N–56°S fishes tied together by their
tails with ribbon. The point
This zodiacal constellation represents where the two ribbons are
two mythical fishes (see panel, right). knotted together is marked by
Its main claim to fame is that it the star Alpha (α) Piscium.
contains the vernal equinox, which is
the point where the Sun crosses the MYTHS AND STORIES
celestial equator into the northern
hemisphere each year in March – EROS AND
on star maps, this is where 0h right
ascension intersects 0° declination. APHRODITE
Because of the slow wobble of the
Earth, known as precession (see p.60), Ancient Greek myths concerning
the point of the vernal equinox is the origins of the constellation of
gradually moving along the celestial Pisces are rather vague. In one
equator and will enter Aquarius in myth, Aphrodite and her son Eros
about AD 2600. transformed themselves into fishes
and plunged into the Euphrates to
SPECIFIC FEATURES escape the fearsome monster
The most distinctive feature of Pisces Typhon. In another version of the
is the ring of seven stars lying south same story, two fishes swam up and
of the Great Square of Pegasus. carried Aphrodite and Eros to
Known as the Circlet, this ring marks safety on their backs.
the body of one of the fishes. It
includes TX Piscium (also known as
19 Piscium), a deep-orange-coloured
red giant that fluctuates irregularly
between magnitudes 4.8 and 5.2.
THE FISHES RESCUE AT SEA
In this 17th-century painting by the Flemish
artist Jacob Jordaens, Aphrodite and Eros are
carried away on the back of a fish.
THE NIGHT SKY M74 54
The spiral galaxy
M74 is seen face on
and appears as a
rounded glow when
viewed through a
small telescope.
Larger apertures are
needed to see its
spiral arms.
THE CONSTELLATIONS
THE SEA MONSTER double star that is more challenging M77 54
to divide than Menkar. High Because it is a Seyfert galaxy, the spiral
Cetus magnification on a telescope is galaxy M77 looks like a fuzzy star
required to see the two component through smaller telescopes – only its
SIZE RANKING 4 stars, of 4th and 7th magnitudes. extremely bright core can be seen.
BRIGHTEST STAR Mira (ο) is the prototype of a Tau (τ) Ceti is 11.9 light-years away. devastating bombardments.Thus the
common type of red giant that Its temperature and brightness make it prospects for life in its vicinity seem
Diphda or Deneb pulsates in size over months or years. the most Sun-like of all Earth’s nearby rather slim.
Kaitos (β) 2.0 Mira can reach magnitude 2 at its stars.Tau is, however, surrounded by a
GENITIVE Ceti brightest – although magnitude 3 is swarm of asteroids and comets, which M77 is found near Delta (δ) Ceti.
more usual – while at its faintest it would subject any local planets to This spiral galaxy is the brightest
ABBREVIATION Cet drops to magnitude 10. Hence, example of a Seyfert galaxy (see Types
depending on how much it has of Active Galaxies, p.310). Related to
HIGHEST IN SKY AT 10PM swollen or contracted within its 11- quasars, Seyfert galaxies are a class of
month cycle, Mira can be either a galaxies that have extremely bright
October–December naked-eye star or one that is visible centres. M77 is oriented face-on
only with a telescope. towards the Earth, although only its
FULLY VISIBLE core is visible through a small
telescope, and it looks only like a
65°N–79°S small, round patch. M77 lies just
under 50 million light-years away.
Cetus is represented on old star charts
as an unlikely looking, almost
comical, hybrid sea monster, although
the figure is also sometimes referred
to as a whale. It is one of the original
48 Greek constellations listed by
Ptolemy in his Almagest. It is a large
but not very obvious constellation
found in the equatorial region of the
sky, and it lies south of the zodiacal
constellations Pisces and Aries. Cetus
is home to the celebrated variable
star, Mira (ο) (see p.281), as well as
a peculiar spiral galaxy, M77.
SPECIFIC FEATURES
Menkar (α) is the second-brightest
star in the constellation. It forms part
of the loop of stars that mark the sea
monster’s head, and it has a wide and
unrelated 6th-magnitude companion
that is visible through binoculars.
Positioned near the neck of
the sea monster is Gamma
(γ) Ceti, a close THE SEA
MONSTER
LURCHING MONSTER 2 MYTHS AND STORIES THE NIGHT SKY
Cetus is large but not particularly prominent.
Its most celebrated star is the variable red THE SEA MONSTER
giant Mira (ο), which for much of the time is
too faint to be seen with the naked eye. Cetus was the sea monster sent to
devour the princess Andromeda
in the famous Greek myth (see
p.352). On his return from killing
Medusa the Gorgon, Perseus spied
Andromeda’s plight and swooped
down on the sea monster as it
attacked, stabbing it repeatedly
with his sword in a fury of blood
and foam, and leaving its water-
logged corpse on the
beach for the local
people to pillage.
MYTHICAL MONSTER
Old star charts depict Cetus with enormous
jaws and a coiled tail, its flippers dipped in the
neighbouring constellation, the river Eridanus.
the constellations
THE HUNTER SPECIFIC FEATURES Betelgeuse contrasts noticeably in picked out from its surrounding glare
Marking one shoulder of Orion is colour with Rigel – Beta (β) Orionis using a small telescope.Two other
Orion Betelgeuse – Alpha (α) Orionis (see – an even more luminous blue easily seen double stars are in Orion’s
p.252) – a red supergiant hundreds of supergiant, which marks one of belt. Delta (δ) Orionis has a 7th-
SIZE RANKING 26 times larger than the Sun. Betelgeuse Orion’s feet. Apart from the rare times magnitude companion, which is
varies irregularly in brightness when Betelgeuse is at its maximum visible through a small telescope or
BRIGHTEST STARS between magnitudes 0.0 and 1.3, but magnitude, Rigel is the brightest star binoculars. It is a greater challenge to
it averages around magnitude 0.5. It is in the constellation. Rigel lies nearly reveal the close 4th-magnitude
Rigel (β) 0.2, about 430 light-years away, and it is 800 light-years from Earth – almost companion of Zeta (ζ) Orionis – this
Betelgeuse (α) 0.5 closer to the Earth than any of the twice as far away as Betelgeuse. Its requires a telescope with an aperture
other bright stars in Orion. 7th-magnitude companion can be of at least 75mm (3in).
GENITIVE Orionis
ABBREVIATION Ori
HIGHEST IN SKY AT 10PM
December–January
FULLY VISIBLE
79°N–67°S
Orion is one of the most glorious
constellations in the sky, representing
a giant hunter or warrior followed by
his dogs, Canis Major and Canis
Minor (see panel, below). Its most
distinctive feature is Orion’s belt,
formed by a line of three 2nd-
magnitude stars almost exactly on the
celestial equator. A complex of stars
and nebulosity represents the sword
that hangs from Orion’s belt and
contains the great star-forming region
of M42, the Orion Nebula (p.239). In
October each year, the Orionid
meteors seem to radiate from a point
near Orion’s border with Gemini.
THE NIGHT SKY MULTIPLE COMPANIONS 5 BRIGHT HUNTER 2
Sigma (σ) Orionis is a remarkable multiple Orion, the hunter, is one of the most
star with three fainter companions – two on magnificent and easily recognizable
one side and an even fainter one on the constellations. A line of three stars
opposite side – appearing rather like a planet makes up his belt, while an area of star
orbited by moons. clusters and nebulae forms his sword.
MYTHS AND STORIES
THE GREAT HUNTER
In Greek mythology, Orion was a tall and
handsome man and the son of Poseidon,
god of the sea.The Greek poet Homer,
in his Odyssey, described Orion as a
great hunter, who brandished a club
of bronze. Despite his hunting
prowess, Orion was killed by a
mere scorpion, some say in
retribution for his boastfulness. In
the sky, Orion is placed opposite
the constellation of Scorpius and,
each night, the hunter flees below
the horizon as the scorpion rises.
HUNTER AND WARRIOR
This depiction of Orion is from an ancient manuscript
based on the Book of Fixed Stars, which was written
by the Arabic astronomer al-Sufi around AD 964.
The real treasures of this constellation colours in faint objects. On clear THE TRAPEZIUM 54
lie in the area around Orion’s sword. nights, it appears to the naked eye as At the heart of the Orion Nebula lies a
NGC 1981, for example, appears as a a hazy patch of light, and is obvious multiple star called the Trapezium (θ1)
large, scattered cluster of stars through through any form of optical aid. An (centre, right). Its four stars are visible
binoculars; its brightest stars are of 6th extension of the Orion Nebula bears through small telescopes but with
magnitude. NGC 1977 is an a separate number, M43, but both are larger apertures, two additional stars
elongated patch of nebulosity part of the same cloud. At the centre can also be seen.
surrounding the stars 42 and 45 of M42 lies a multiple star,Theta-1
Orionis. Nearby is the Orion Nebula, (θ1) Orionis (see p.277), better known THE ORION NEBULA REGION
an enormous star-forming cloud of as the Trapezium because it appears as
gas, 1,500 light-years away, covering a group of four stars of 5th to 8th
an area of sky wider than two magnitude when seen through a small
diameters of the Moon. Its glowing telescope.To one side of the nebula
gas appears multi-coloured on lies Theta-2 (θ2) Orionis, a double
photographs and CCD images, yet star with components of 5th and 6th
visually it looks only grey-green magnitudes that can be separated with
because the eye is not sensitive to binoculars. At the tip of Orion’s
sword lies Iota (ι) Orionis, a double,
THE HUNTER with components of 3rd and 7th
magnitudes, divisible with a small
telescope. Struve 747 is a wider MAGNITUDE KEY THE ORION NEBULA 54
double star nearby, with components To the naked eye and
of 5th and 6th magnitudes. 0.0–0.9 through binoculars, the Orion
Nebula (M42) appears only
Even more impressive is the 1.0–1.9 as a misty patch, south of
multiple star Sigma (σ) Orionis Orion’s belt, its heart lit up
(p.277). A small telescope shows that 2.0–2.9 by new-born stars. Its full
the main 4th-magnitude star has two 3.0–3.9 beauty and its pinkish colour
7th-magnitude companions on one 4.0–4.9 become apparent only on
side and a closer 9th-magnitude 5.0–5.9 photographs and CCD
component on the other. 6.0–6.9 images such as this.
Extending from the belt star
Zeta (ζ) Orionis is a strip of bright
nebulosity, IC 434, against which is
silhouetted the Horsehead Nebula
(see p.238).This is probably the best-
known dark nebula in the sky, and it
shows well on photographs.To see it
visually requires a large telescope and
a dark viewing site.
THE HORSEHEAD NEBULA 43 THE NIGHT SKY
Looking like a knight in a celestial chess
game, the Horsehead Nebula is a curiously
shaped dark dust cloud silhouetted against
IC 434, a backdrop of glowing hydrogen. It
lies to the south of Zeta (ζ) Orionis (centre
left) in Orion’s belt.
the constellations
THE GREATER DOG SPECIFIC FEATURES NGC 2362 5
Sirius is a more powerful star The brightest member of
Canis Major than the Sun, giving out about this neat cluster of stars
20 times as much light, and it is the 4th-magnitude blue
SIZE RANKING 43 is among the closest stars to supergiant Tau (τ) Canis
the Earth, being 8.6 light-years Majoris, which is almost
BRIGHTEST STARS away. In combination, these at its centre.
factors give Sirius an apparent
Sirius (α) -1.4, brightness twice that of the second- THE
Adhara (ε) 1.5 brightest star, Canopus (in Carina). GREATER
Sirius is accompanied by a faint white DOG
GENITIVE dwarf, Sirius B (see p.264), which
orbits it every 50 years.
Canis Majoris
ABBREVIATION CMa M41 is a large open cluster that is
visible as a hazy patch to the naked
HIGHEST IN SKY AT 10PM eye. Its stars, which are scattered over
an area about the size of the full
January–February Moon, are revealed with binoculars,
while telescopes show chains of stars
FULLY VISIBLE radiating from its centre.
56°N–90°S Around Tau (τ) Canis Majoris is
NGC 2362, which is best viewed
This southern constellation contains with a telescope. Also nearby is UW
the brightest star in the entire sky: Canis Majoris, an eclipsing binary.
Sirius, or Alpha (α) Canis Majoris
(see p.248). It forms a triangle with ORION’S HUNTING DOG 2
Procyon (in Canis Minor) and The great dog stands on its hind legs in the
Betelgeuse (in Orion). Canis Major sky, holding brilliant Sirius in its jaws like
was known to the ancient Greeks as a sparkling ball.
one of the two dogs following Orion,
the hunter (see panel, below).
MYTHS AND STORIES
LAELAPS
This mythical dog was so swift that no prey could
escape it, except for the Teumessian Fox, which
was destined never to be caught. Laelaps was sent
off in pursuit of the fox, which was
creating havoc near the town of FACING LEFT
Thebes, north of Athens, but it was In common with
an unending chase. Zeus ended the many other older
pursuit by turning them both to depictions of the
stone, and placed the dog in the sky constellations, Canis
Major is shown here
as Canis Major – but without the fox. as a mirror image.
THE LITTLE DOG SPECIFIC FEATURES THE LITTLE
Procyon is the eighth-brightest star DOG
Canis Minor in the sky. It is somewhat cooler and
fainter than the other dog star, Sirius,
SIZE RANKING 71 and also more distant, lying 11.4
light-years away. It has a white dwarf
BRIGHTEST STAR partner, Procyon B, which is visible
only with a very large telescope.
Procyon (α) 0.4
GENITIVE
Canis Minoris
ABBREVIATION CMi
HIGHEST IN SKY AT 10PM
February
FULLY VISIBLE
89°N–77°S
THE NIGHT SKY Canis Minor is one of the original LONE STAR 2
Greek constellations and lies virtually Unlike the distinctive constellation of the
on the celestial equator. It is usually Greater Dog, Canis Minor consists of little
identified as the smaller of Orion’s more than its brightest star, Procyon.
two hunting dogs.
The constellation is easily
identified by its brightest star –
Procyon, or Alpha (α) Canis Minoris
(see p.280) – which forms a large
sparkling triangle with two other
1st-magnitude stars: Betelgeuse (in
Orion) and Sirius (in Canis Major).
Other than that, the constellation
contains little of particular note to
small telescope users.
the constellations
THE UNICORN Although none of the stars of well only on CCD THE CONE NEBULA 543
Monoceros is bright, the Milky Way images and This tapering region of dark gas and dust
Monoceros passes through it and it contains many photographs. intrudes into brighter nebulosity at the
deep-sky objects of interest. southern end of the star cluster NGC 2264.
SIZE RANKING 35 NGC 2264 is The Cone Nebula is visible only on images
The constellation was introduced another combination taken with a large telescope, as here.
BRIGHTEST STAR in the early 17th century by the of open cluster and
Dutch astronomer and cartographer nebula.This triangular
Alpha (α) 3.9 Petrus Plancius and depicts the group can be seen
unicorn, a mythical animal with through binoculars or
GENITIVE religious symbolism. a small telescope. Its
brightest member is
Monocerotis SPECIFIC FEATURES 5th-magnitude
ABBREVIATION Mon Beta (β) Monocerotis (see p.277) is S Monocerotis – an
regarded as one of the finest triple intensely hot and
HIGHEST IN SKY AT 10PM stars in the sky for small instruments. luminous star that
It is readily separated to show an arc is slightly variable.
January–February of three 5th-magnitude stars. CCD images and
photographs show a
FULLY VISIBLE The double star Epsilon (ε) surrounding nebulosity
Monocerotis is labelled 8 Monocerotis into which encroaches a dark wedge
78°N–78°S on some charts. Its components, of called the Cone Nebula (see p.240).
4th and 7th magnitudes, are easily
Monoceros is often overlooked, spotted through a small telescope. M50 is an open cluster about half
because it is overshadowed by the apparent size of the full Moon.
neighbouring Orion, Gemini, and Prime among Monoceros’s most It is visible through binoculars but a
Canis Major. It is easy to locate, celebrated clusters and nebulae is telescope is needed to resolve its
however, as it is situated on the NGC 2244, an elongated group individual stars.
celestial equator in the middle of the of stars of 6th magnitude and
large triangle formed by the brilliant fainter. Surrounding the cluster is a NGC 2232 is larger and more
1st-magnitude stars Betelgeuse (in glorious nebula known as the Rosette scattered, and its brightest stars are
Orion), Procyon (in Canis Minor), Nebula, although it is faint and seen visible through binoculars.
and Sirius (in Canis Major).
FRAMED BEAST 2
Monoceros occupies the space within the
bright triangle of stars formed by Sirius
(seen here at upper right), Betelgeuse
(upper left), and Procyon (bottom centre).
THE ROSETTE NEBULA 54
The flower-like form of the Rosette Nebula
glows like a pink carnation in this CCD
image. At its centre is the star cluster
NGC 2244, which can readily be identified
through binoculars.
THE UNICORN
THE NIGHT SKY
the constellations
THE WATER SNAKE MYTHS AND STORIES
Hydra HERCULES AND THE HYDRA
SIZE RANKING 1 The Hydra was a serpent with nine
heads, one of them immortal, which
BRIGHTEST STAR lived in a swamp near the town of
Lerna, emerging to ravage crops and
Alphard (α) 2.0 cattle. As the second of his labours,
GENITIVE Hydrae Hercules was sent to kill the
monster. He flushed it from its
ABBREVIATION Hya lair with flaming arrows and cut
off each head in turn, ending with
HIGHEST IN SKY AT 10PM the immortal head, which he
buried under a rock.
February–June
FULLY VISIBLE
54°N–83°S
Hydra depicts the multi-headed DEADLY BLOWS LONG SERPENT 2
monster that fought and was killed by Hercules battles with the Hydra in this sculpture by The Hydra’s head, at the right in this
Hercules in the second of his labours François-Joseph Bosio (1768–1845), which is photograph, lies south of Cancer (and, in
(see panel, right). During the struggle, exhibited in the Tuileries gardens, Paris. this view, the disc of Jupiter), while the
a crab joined forces with the Hydra tip of its tail lies far to the left.
but was crushed underfoot by divided with a telescope with an
Hercules; it was later commemorated aperture of at least 75mm (3in)
as the constellation Cancer. Although and high magnification.The yellow
the Hydra had nine heads, it is and blue component stars are of
represented in the sky with a single magnitude 3.4 and 6.7 and have an
head – presumably its immortal one. orbital period of nearly 1,000 years.
The constellation is the largest of M48 is an open star cluster on
all 88 and stretches for more than a the border with Monoceros. It lies
quarter of the way around the sky nearly 2,000 light-years away. M48
from its head, south of Cancer and is larger than the full Moon and it is
just north of the celestial equator, to seen well through binoculars or a
its tail in the southern hemisphere small telescope. It contrasts with the
between Libra and Centaurus. Despite globular cluster M68 (see p.289),
its size, there is little to mark out this which resembles a fuzzy star when
constellation other than a group of six viewed through binoculars or a
stars of modest brightness, which small telescope.
forms the head of the water snake.
M83 is a spiral galaxy, towards the
SPECIFIC FEATURES Hydra’s tail, that lies about 15 million
Hydra’s brightest star is 2nd-magnitude light-years away.Through a small
Alphard, or Alpha (α) Hydrae. Alphard telescope, it appears as an elongated
means “the solitary one”, and this glow, but a telescope of larger
name reflects its position in an apertures will reveal its spiral structure
otherwise blank area of sky.This and its noticeable central “bar”, which
orange-coloured giant is in fact the may be similar to the bar that is
only star in the constellation brighter thought to lie across the centre of
than magnitude 3.0. It is about 175 the Milky Way Galaxy.
light-years away. Epsilon (ε) Hydrae is
a close binary star with components The planetary nebula known as
of contrasting colours that can be the Ghost of Jupiter, or NGC
3242, is to be found near the star
Mu (μ) Hydrae, in the central part
of Hydra’s body.
THE NIGHT SKY THE GHOST OF JUPITER 54
When viewed through a small
telescope, the planetary nebula NGC
3242 appears as an ethereal, blue-
green, elliptical glow about the size
of the planet Jupiter, hence its
popular name – the Ghost of Jupiter.
M83 54
This magnificent face-on spiral
galaxy is to be found lying on the
border of Hydra and Centaurus. M83
has a central “bar” of stars and gas,
and it is sometimes known as the
Southern Pinwheel.
THE WATER SNAKE THE NIGHT SKY
the constellations
THE AIR PUMP this case, an air pump designed by the
French physicist Denis Papin for his
Antlia experiments on gases.
SIZE RANKING 62 SPECIFIC FEATURES THE AIR PUMP
Zeta (ζ) Antliae appears as a wide pair
BRIGHTEST STAR of 6th-magnitude stars when viewed
through binoculars.The brighter
Alpha (α) 4.3 of the pair has a companion of
GENITIVE Antliae 7th magnitude.
ABBREVIATION Ant
NGC 2997 is an elegant spiral
HIGHEST IN SKY AT 10PM galaxy inclined at about 45 degrees to
our line of sight. Unfortunately, it is
March–April just too faint to be well seen through
a small telescope, although it can be
FULLY VISIBLE captured beautifully on photographs
and CCD images. NGC 2997 is
49°N–90°S about 35 million light-years away.
This constellation was one of those NGC 2997 54
introduced in the mid-18th century by This classic spiral galaxy reveals pink
the French astronomer Nicolas Louis clouds of hydrogen gas dotted along
de Lacaille (see p.406) to commemorate its spiral arms in CCD images.
scientific and technical inventions – in
THE SEXTANT NORTH OF VELA 2
Antlia is an inconspicuous grouping in
Sextans the southern hemisphere and consists of
a handful of stars to be found between
SIZE RANKING 47 Vela and Hydra.
BRIGHTEST STAR THE SEXTANT
Alpha (α) 4.5 THE SPINDLE GALAXY 54
GENITIVE Sextantis NGC 3115 is a lenticular galaxy
seen edge-on from Earth, so it
ABBREVIATION Sex appears highly elliptical in
shape when viewed through a
HIGHEST IN SKY AT 10PM telescope. It is just over 30
million light-years from us.
March–April
FULLY VISIBLE
78°N–83°S
THE NIGHT SKY Representing a sextant used for taking HEVELIUS’S SEXTANT 2
star positions in the days before Sextans is difficult to pick out with the
telescopes were invented, Sextans was naked eye because it is a faint and
introduced in the late 17th century unremarkable constellation. It lies on
by the Polish astronomer Johannes the celestial equator south of Leo.
Hevelius (see p.368), who used such a
device when cataloguing the stars.
SPECIFIC FEATURES
Two unrelated stars of 6th magnitude
– 17 and 18 Sextantis – form a line-
of-sight double star, which shows
neatly through binoculars.
In the same part of the
constellation lies NGC 3115, which is
popularly named the Spindle Galaxy
because of its highly elongated shape.
This lenticular galaxy is detectable
through a small telescope.
THE CUP the constellations
Crater MYTHS AND STORIES
SIZE RANKING 53 THE CUP CROW AND CUP
BRIGHTEST STAR Crater and Corvus feature together
in a Greek myth in which the god
Delta (δ) 3.6 Apollo sent the crow (Corvus) to
GENITIVE Crateris fetch water in a cup (Crater). On
the way, the greedy crow stopped
ABBREVIATION Crt to eat figs. As an alibi, the crow
snatched up a water snake (Hydra)
HIGHEST IN SKY AT 10PM and blamed it for delaying him but
Apollo saw through the deception
April and banished the trio to the skies.
FULLY VISIBLE HISTORIC DEPICTION
The area around Crater as
65°N–90°S shown in Urania’s Mirror,
a set of 19th-century
Crater is a faint constellation constellation
representing a cup. Although larger cards.
than Corvus, to which it is linked in
Greek myth (see panel, right), Crater CELESTIAL VESSEL 2
contains no objects that might be of Crater is to be found lying next to Corvus on
interest to users of small telescopes. the back of Hydra, the water snake. This
undistinguished constellation is also known
This area once contained two as the goblet or the chalice.
other constellations that have since
been dropped by astronomers. In the
late 18th century, a French
astronomer, J.J. Lalande, introduced
Felis, the cat, between Hydra and
Antlia, while others introduced
Noctua, the night owl, on the tail of
Hydra (see panel illustration, right).
THE CROW
Corvus
SIZE RANKING 70 THE CROW
BRIGHTEST STAR
Gamma (γ) 2.6
GENITIVE Corvi
ABBREVIATION Crv
HIGHEST IN SKY AT 10PM
April–May
FULLY VISIBLE
65°N–90°S
The four brightest stars of Corvus – THE ANTENNAE 43
Beta (β), Gamma (γ), Delta (δ), and As NGC 4038 and 4039 sweep past
Epsilon (ε) Corvi – form a distinctive each other, gravity draws out
keystone shape in this small long streams of dust and
gas from them. The
constellation south of Virgo. Oddly, streams extend off
the star labelled Alpha (α) Corvi, at the top and
magnitude 4.0, is significantly fainter bottom of
this picture.
than all of these. Corvus is one of the
original 48 Greek constellations and
represents a crow, the sacred bird of
the Greek god Apollo.
SPECIFIC FEATURES PECKING BIRD 2 THE NIGHT SKY
Delta is a double star with Corvus, the crow, is linked in legend with
components of 3rd and 9th neighbouring Crater, the cup. The crow
magnitudes. It is divisible through is visualized as pecking at Hydra, the
a small telescope. water snake, on whose back it stands.
Corvus also boasts a remarkable
pair of interacting galaxies: NGC 4038
and 4039. At 10th magnitude, they
are too faint to be seen through a
small telescope, but photographs reveal
this as a graphic example of a galactic
collision.When the galaxies passed by
each other, gravity pulled out stars and
gas to create a shape like an insect’s
feelers, hence their popular name, the
Antennae (see p.307).
the constellations
THE CENTAUR
Centaurus
SIZE RANKING 9 THE CENTAUR MYTHS AND STORIES
BRIGHTEST STARS Although it bears a Greek CHIRON
letter, Omega (ω) Centauri
Rigil Kentaurus (α) is not a star but a globular The wise and scholarly centaur Chiron
-0.3, Hadar (β) 0.6 cluster, the largest and brightest was the offspring of Cronus, king of the
visible from Earth.To the naked Titans, and the sea nymph Philyra. He
GENITIVE Centauri eye, it is a large, hazy star, and a lived in a cave, from where he taught
small telescope is required to hunting, medicine, and music to the
ABBREVIATION Cen resolve the brightest individual offspring of the gods. His most successful
members of this globular cluster. pupil was Asclepius, son of Apollo, who
HIGHEST IN SKY AT 10PM became the greatest healer of the ancient
Almost due north of Omega is world. Chiron was immortalized among
April–June the peculiar galaxy NGC 5128, also the stars after Heracles accidentally shot
known as the radio source Centaurus him with a poisoned arrow.
FULLY VISIBLE A (see p.312).This object is thought
to result from the merger of a giant TEACHER OF THE GODS
25°N–90°S elliptical galaxy and a spiral galaxy. This Roman fresco shows Chiron teaching
Photographs show a dark band of Achilles, his foster-son, to play the lyre.
This dominating constellation of the dust across the galaxy’s centre, the They are in Chiron’s cave on Mount Pelion.
southern skies contains a variety of remains of the spiral galaxy, but larger
notable objects, including the closest apertures are needed to make out this
star to the Sun and a most unusual feature visually. NGC 5128 is the
galaxy. Centaurus represents the brightest galaxy outside the Local
centaur Chiron (see panel, right), who Group and, at a distance of about
had the torso of a man and the four 12 million light-years, is the closest
legs of a horse. peculiar galaxy to us.
SPECIFIC FEATURES The planetary nebula NGC 3918,
Alpha (α) Centauri (see p.248), or or the Blue Planetary, is easily
Rigil Kentaurus, is a fabulous multiple identified through a small telescope.
star.To the naked eye, it is the third- It appears like a larger version of the
brightest star in the sky. Its system disc of Uranus. Also in Centaurus
includes two Sun-like stars, which are two interesting open star clusters
appear so bright because they are only NGC 3766 and NGC 5460.
4.4 light-years away, closer than any
other stars bar one – Proxima
Centauri (see p.248), which is about
0.2 light-years closer. However,
Proxima is of only magnitude 11 and
lies four diameters of the full Moon
away from its brighter companions. Its
position means it is outside Alpha’s
telescopic field of view, so
identification is difficult.
THE NIGHT SKY ALPHA CENTAURI 5
The two yellow stars, of magnitudes 0.0 and
1.4, of this beautiful double star orbit each
other every 80 years. They are easily
separated through a small telescope.
CELESTIAL CENTAUR 2
The brilliant stellar pairing of Alpha (α)
and (β) Beta Centauri guides the eye to
Centaurus, the celestial centaur. The familiar
pattern of Crux, the Southern Cross, lies
beneath the centaur’s body.
THE WOLF magnitude companion visible the constellations
through a small telescope. Its
Lupus primary star, however, is a close THE WOLF
double, needing an aperture of at
SIZE RANKING 46 least 100mm (4in) to separate. BESTIAL OFFERING 2
Here, Lupus is partly surrounded by
BRIGHTEST STAR The 3rd-magnitude Epsilon (ε) the stars of Centaurus. In Greek
Lupi has a companion of 9th myth, the centaur killed the beast
Alpha (α) 2.3 magnitude, and Eta (η) Lupi is a and carried it to the altar, Ara.
GENITIVE Lupi 3rd-magnitude star with an 8th-
magnitude companion.
ABBREVIATION Lup
NGC 5822 is a rich open cluster
HIGHEST IN SKY AT 10PM within the Milky Way. Its brightest
stars are of only 9th magnitude, so it
May–June is not particularly prominent. It lies
2,400 light-years away.
FULLY VISIBLE
34°N–90°S
Lupus is a southern constellation NGC 5822 5
lying on the edge of the Milky Way This large open cluster in southern
between the better-known figures of Lupus contains more than 100
Centaurus and Scorpius. It contains stars of 9th magnitude
numerous double stars of interest to and fainter. It can
amateur observers. be seen through
binoculars or
It was one of the original 48 a small
constellations familiar to the ancient telescope.
Greeks, who visualized it as a wild
animal speared by Centaurus (see
panel, below).
SPECIFIC FEATURES
Kappa (κ) Lupi, with components of
magnitudes 3.9 and 5.7, and Xi (ξ)
Lupi, with components of magnitudes
5.1 and 5.6, are two doubles that are
easy to spot through a small telescope.
Pi (π) Lupi can be divided into
matching 5th-magnitude components
through a telescope with an aperture
of 75mm (3in). Even more
challenging is 4th-magnitude Mu (μ)
Lupi, which has a wide 7th-
MYTHS AND STORIES
THE LANCED BEAST
To the ancient Greeks and
Romans, Lupus represented a wild
animal of unspecified nature which
had been speared, by neighbouring
Centaurus, on a long pole called a
thyrsus. In consequence, Centaurus
and Lupus were often regarded
as a combined figure.The
identification of Lupus as a wolf
seems to have become common
during Renaissance times.
IN MIRROR IMAGE
This medieval Arabic illustration shows
Centaurus holding Lupus and the thyrsus,
which has become a
bunch of leaves
or flowers.
THE NIGHT SKY
THE constellations
THE ARCHER Although old star charts depicted this Omega Nebula, M17.The loose M22 15
constellation as a centaur, in Greek cluster of stars within it can be This prominent globular cluster lies near the
Sagittarius mythology Sagittarius was identified detected through binoculars. lid of the Teapot. Through binoculars, it
as a different type of creature, known appears as a woolly ball about two-thirds
SIZE RANKING 15 as a satyr. He is usually said to be M22 is one of the finest globular the apparent diameter of the Moon.
Crotus, son of Pan, who invented clusters in the entire sky. Under good
BRIGHTEST STAR archery and went hunting on conditions, it is visible to the naked
horseback. He is seen aiming his bow eye.Through a small telescope, it is
Epsilon (ε) 1.8 at neighbouring Scorpius. somewhat elliptical in outline, while
one with an aperture of 75mm (3in)
GENITIVE Sagittarii SPECIFIC FEATURES will resolve its brightest stars.
Beta (β) Sagittarii appears to the
ABBREVIATION Sgr naked eye as a pair of 4th-magnitude M23 is a large open cluster visible
stars.The more northerly (and slightly through binoculars near the border
HIGHEST IN SKY AT 10PM brighter) of the two stars has a 7th- with Ophiuchus. M25 is another
magnitude companion. All three stars binocular cluster, while M24 is a
July–August are at different distances, bright Milky Way star field the length
and hence are unrelated. of four diameters of the full Moon.
FULLY VISIBLE
Probably the finest
44°N–90°S object for binoculars is
M8, the Lagoon Nebula
This prominent zodiacal constellation (see p.241), which
is found between Scorpius and extends for three times
Capricornus, in the southern celestial the width of the full
hemisphere. It includes a highly Moon. It contains the
recognizable star pattern called the cluster NGC 6530, with
Teapot, with a pointed lid (λ) and stars of 7th magnitude
large spout (γ, ε, and δ).The handle and fainter, as well as the
of the Teapot is sometimes also called 6th-magnitude blue
the Milk Dipper. supergiant 9 Sagittarii.
The Milky Way is particularly The Trifid Nebula,
broad and rich in Sagittarius, because M20 (see p.244), is so-
the centre of our Galaxy (Sagittarius named because it is
A) lies in this direction.The exact trisected by dark lanes
centre of the Galaxy is thought to of dust.Visually, it is far
coincide with a radio source known less impressive than its
as Sagittarius A*, near where the photographic representation,
borders of Sagittarius, Ophiuchus, and and little more than the faint
Scorpius meet. Sagittarius boasts more double star at its centre can
Messier objects than any other be identified through a small
constellation – it has 15 in all. instrument.
On the northern border
of Sagittarius with Scutum
lies another frequently
photographed object – the
THE LAGOON NEBULA 154
One of the largest nebulae in the sky
is M8, which appears in binoculars as an
elongated, milky patch of light with
embedded stars, including those in the
cluster NGC 6530, which make it glow.
THE ARCHER
THE NIGHT SKY THE TRIFID NEBULA 54 THE OMEGA NEBULA
The pinkish emission of the Trifid
Nebula contrasts with the blue 154
reflection nebula to its north, M17 can be glimpsed
as revealed on long-exposure through binoculars but
photographs and CCD images. shows up better through a
At its heart is a faint double star, telescope. It resembles
which is overexposed on this image. the Greek capital letter
omega (Ω). However,
others see it as a swan,
hence its alternative
name, the Swan Nebula.
MOUNTED BOWMAN 2
The stars that make up the outline of
Sagittarius, the Archer, lie in front of
dense Milky Way star fields towards the
centre of our Galaxy. North is to the left
in this photograph.
THE NIGHT SKY
the constellations
THE SCORPION SPECIFIC FEATURES also be seen. All four stars are
Antares, or Alpha (α) Scorpii (see gravitationally linked, making this
Scorpius p.252), is a red supergiant hundreds of a genuine quadruple.
SIZE RANKING 33 times larger than the Sun. It fluctuates The open cluster M7 is visible to
the naked eye as a hazy patch. It has
BRIGHTEST STAR from about magnitude 0.9 to 1.2 dozens of stars of 6th magnitude and
fainter scattered over an area twice
Antares (α) 1.0 every four to five years. the apparent width of the full Moon.
(variable) Normally, Delta (δ) Scorpii is of About twice as distant is M6, which is
known as Butterfly Cluster (see p.286)
ABBREVIATION Sco magnitude 2.3, but in the year 2000 because of its shape when viewed
through binoculars. On one wing lies
GENITIVE Scorpii it unexpectedly began to brighten BM Scorpii, a variable orange giant.
Near Antares, M4 (see p.288) is one
HIGHEST IN SKY AT 10PM by over 50 per cent.Whether it will of the closest globular clusters to us, at
7,000 light-years away.
June–July remain at its new magnitude or return
Just too far south to have featured
FULLY VISIBLE to its previous value is unknown. on Charles Messier’s list (see p.69) is
Beta (β) Scorpii is a line-of-sight the open cluster NGC 6231. Its
44°N–90°S brightest member, 5th-magnitude
pair with components of 3rd and 5th Zeta (ζ) Scorpii, has a 4th-magnitude
This beautiful and easily recognizable magnitudes, while Omega (ω) Scorpii companion much closer to us. GLITTERING CLUSTERS 21
zodiacal constellation is situated in the is an even wider unrelated pair, with Two prominent star clusters,
southern sky. It depicts a scorpion (see The strongest X-ray source in M6 and M7, adorn the tail of
panel, below), whose raised tail is stars of 4th magnitude. A small the sky is Scorpius X-1.This consists Scorpius in the Milky Way.
marked by a curve of stars extending telescope easily splits Nu (ν) Scorpii of a 13th-magnitude blue star orbited M6 is at the centre of
into a rich area of the Milky Way into a double with components of 4th by a neutron star. this photograph; M7
towards the centre of the Galaxy. and 6th magnitudes. Mu (μ) Scorpii is is bottom left.
another naked-eye pair, with stars of
THE SCORPION
3rd and 4th magnitudes.
More complex is Xi (ξ) Scorpii, a
white and orange pair of stars of 4th
and 7th magnitudes. In the same field
of view a fainter and wider pair can
THE NIGHT SKY STING IN THE TAIL 2 MYTHS AND STORIES
This view of Scorpius has south at the
top and shows the scorpion raising its THE DEATH OF ORION
curving tail as though to strike. Its heart
is marked by the red star Antares. In Greek mythology, Scorpius was the
scorpion that stung Orion to death.
According to one story the scorpion was
sent by Artemis, the goddess of hunting,
after Orion had tried to attack her,
while another account relates how
Mother Earth dispatched the
scorpion to humble Orion after
he had boasted that he could
kill any wild beast.
MISPLACED FOOT
Like other old star charts, Jean Fortin’s
Atlas Céleste shows the foot of Ophiuchus
awkwardly overlapping Scorpius.
THE SEA GOAT M30 15 THE NIGHT SKY
Chains of stars
Capricornus extending like
fingers from the
SIZE RANKING 40 northern side of
this cluster are
BRIGHTEST STAR Deneb visible through a
Algedi (δ) 2.9 large telescope.
GENITIVE Capricorni
THE SEA GOAT
ABBREVIATION Cap
MYTHS AND STORIES
HIGHEST IN SKY AT 10PM
PAN
August–September
This Greek god of the countryside
FULLY VISIBLE had the hind legs and horns of a
male goat but the body of a
62°N–90°S human. He created the pipes of
Pan, also known as the syrinx,
This is the smallest constellation of from reeds of different length.
the zodiac and not at all prominent;
it is situated in the southern sky PANPIPER
between Sagittarius and Aquarius. In This stone statue of Pan playing his reed
Greek myth, Capricornus represents pipes is to be found in the garden of a
the goat-like god Pan (see panel, castle in Schwetzingen, Germany.
right), who jumped into a river and
became part-fish to escape from the CAPRICORNUS AND MARS 2
monster Typhon. Mars is here seen here to the left
of Capricornus, whose stars form a
SPECIFIC FEATURES roughly triangular shape depicting
Alpha (α) Capricorni is a wide Pan as half-goat half-fish.
pairing of unrelated 4th-magnitude
stars.They can be separated through THE MICROSCOPE
binoculars or even with good UNDER THE MICROSCOPE 2
eyesight. Alpha-1 (α1) Capricorni is a
yellow supergiant nearly 700 light- Microscopium is a faint and almost
years away, while Alpha-2 (α2) is a featureless constellation. It lies near
yellow giant less than one-sixth that Capricornus and the much more
distance from the Earth. conspicuous Sagittarius.
Beta (β) Capricorni is a 3rd-
magnitude yellow giant with a 6th-
magnitude blue-white companion
that can be seen through a small
telescope or even good binoculars.
The modest globular cluster M30
is visible as a hazy patch through a
small telescope.
THE MICROSCOPE
Microscopium
SIZE RANKING 66
BRIGHTEST STARS
Gamma (γ) 4.7, Epsilon
(ε) 4.7
GENITIVE Microscopii
ABBREVIATION Mic
HIGHEST IN SKY AT 10PM
August–September
FULLY VISIBLE
45°N–90°S
Microscopium is a faint and obscure
southern constellation to be found
between Sagittarius and Piscis
Austrinus. It was invented in the 18th
century by the French astronomer
Nicolas Louis de Lacaille (see p.406),
and it represents an early design of
compound microscope.
SPECIFIC FEATURES
The orange giant Alpha (α)
Microscopii, of 5th magnitude, has a
10th-magnitude companion that is
visible through an amateur telescope.
the constellations
THE SOUTHERN FISH SPECIFIC FEATURES
Beta (β) Piscis Austrini is a wide
Piscis Austrinus double star with components of 4th
and 8th magnitudes. It is divisible
SIZE RANKING 60 through a small telescope.
BRIGHTEST STAR More difficult to separate with a
small telescope is Gamma (γ) Piscis
Fomalhaut (α) 1.2 Austrini, a closer pair of stars of
GENITIVE Piscis 5th and 8th magnitudes.
Austrini
THE SOUTHERN
ABBREVIATION PsA FISH
HIGHEST IN SKY AT 10PM
September–October
FULLY VISIBLE
53°N–90°S
Piscis Austrinus was known to the
ancient Greeks, including Ptolemy in
the 2nd century AD. It depicts a fish,
which was said to be the parent of
the two fishes represented by the
zodiacal constellation Pisces.
This constellation has also
been called Piscis Australis. It is
made prominent in the southern
hemisphere by the presence of 1st-
magnitude Fomalhaut, or Alpha (α)
Piscis Austrini (see p.249).This blue-
white star lies 25 light-years away.
NEVER-ENDING DRINK 2
In the sky, water from the jar of the adjacent
Aquarius, the Water Carrier, flows towards
the mouth of the fish, marked by Fomalhaut.
The star’s name is an Arabic term meaning
“fish’s mouth”.
THE SCULPTOR The spiral galaxy NGC 253 is
seen nearly edge-on, so that it
Sculptor appears highly elongated. Under
good sky conditions, it can be
SIZE RANKING 36 picked up through binoculars
or a small telescope. Nearby lies
BRIGHTEST STAR the fainter and smaller globular
cluster NGC 288. Another spiral
Alpha (α) 4.3 galaxy is NGC 55, which is similar
GENITIVE Sculptoris in size and shape to NGC 253.
ABBREVIATION Scl
HIGHEST IN SKY AT 10PM
October–November
FULLY VISIBLE
50°N–90°S
THE NIGHT SKY This unremarkable southern THE SCULPTOR NGC 55 54
constellation was introduced in This patchy-looking
the 18th century by the French BRIGHT NEIGHBOUR 2 spiral galaxy, seen
astronomer Nicolas Louis de Lacaille The faint constellation of nearly edge-on, is
(see p.406). He originally described Sculptor is outshone by mottled with dust
it as representing a sculptor’s studio, Fomalhaut, the leading clouds and areas of
although the name has since star of adjoining Piscis star formation.
been shortened. Austrinus, seen below
Sculptor in this image.
Sculptor contains the south pole
of our Galaxy – that is, the point 90
degrees south of the plane of the
Milky Way. As a result, we can see
numerous far-off galaxies in this
direction, as they are unobscured by
intervening stars or nebulae.
SPECIFIC FEATURES
Epsilon (ε) Sculptoris is a binary star
that can be separated with a small
telescope. Its components, of 5th and
9th magnitudes, have an orbital
period of more than 1,000 years.
THE FURNACE chemists for distillation. It was the constellations
originally known by the name
Fornax Fornax Chemica, the chemical NGC 1365 534
furnace, but this has since been This barred spiral galaxy is the
SIZE RANKING 41 shortened to Fornax. largest in the Fornax Cluster and is
about as massive as the Milky Way.
BRIGHTEST STAR Alpha
(α) 3.9 It can be identified through a
moderate-sized telescope.
GENITIVE Fornacis
SPECIFIC FEATURES THE FORNAX CLUSTER 534
ABBREVIATION For The brightest star in the constellation, Most of the galaxies in this cluster
4th-magnitude Alpha (α) Fornacis, in southern Fornax are ellipticals,
HIGHEST IN SKY AT 10PM has a yellow companion, which including the 10th-magnitude
orbits it every 300 years.This 7th- NGC 1399 (left of centre in this
November–December magnitude star is visible through a photograph). Standing out among the
small telescope. elliptical galaxies is the large barred
FULLY VISIBLE spiral NGC 1365 (bottom right).
On the border of Fornax with
50°N–90°S Eridanus lies a small cluster of galaxies THE FURNACE
known as the Fornax Cluster (see
A handful of faint stars makes up this p.319). It is about 65 million light-
undistinguished constellation of the years away, and its brightest member –
southern sky. Fornax is situated on the peculiar spiral NGC 1316 – is a
the edge of Eridanus and Cetus, and radio source known as Fornax A.
it represents a furnace used by Another prominent member of the
Fornax Cluster is the beautiful barred
spiral galaxy NGC 1365.
PROTECTED POSITION 2
Fornax is tucked into a bend in the
celestial river, Eridanus. It was
introduced by Nicolas Louis de
Lacaille during the 18th century.
THE CHISEL THE CHISEL
Caelum ENGRAVED IN STONE 2
Beta (β) and Alpha (α) Caeli mark the
SIZE RANKING 81 shaft of the celestial chisel, which
points towards the constellations
BRIGHTEST STAR Alpha Dorado and Reticulum in the south.
(α) 4.4
ABBREVIATION Cae
GENITIVE Caeli
HIGHEST IN SKY AT 10PM
December–January
FULLY VISIBLE
41°N–90°S
Sandwiched between Eridanus and THE NIGHT SKY
Columba is this small and faint
southern constellation, which was
introduced in the 18th century by the
French astronomer Nicolas Louis de
Lacaille (see p.406). It represents a
stonemason’s chisel.
SPECIFIC FEATURES 8th-magnitude companion. Because
Gamma (γ) Caeli is a double star, they are positioned close together,
consisting of an orange giant a modest-sized telescope is required
in order to separate them.
of magnitude 4.6, with an
390 the constellations
THE RIVER and fell into the river below.This river The galaxy NGC 1300 is estimated to
Eridanus has been identified with two real ones: lie around 75 million light-years away
the Nile in Egypt and the Po in Italy. and is too faint for viewing through a
small telescope. However, it shows up
SIZE RANKING 6 SPECIFIC FEATURES beautifully on photographs.
BRIGHTEST STAR For all its size, Eridanus is short
Achernar (α) 0.5 on objects of interest for a small MULTIPLE STAR
GENITIVE Eridani
telescope.The best is the multiple star The primary star of Omicron-2 (ο2) Eridani
ABBREVIATION Eri Omicron-2 (ο2) Eridani (see p.272), is in the centre of this photograph, while its
HIGHEST IN SKY AT 10PM also known as 40 Eridani, which white-dwarf and red-dwarf companions
November–January includes both a red dwarf and a white overlap each other to the right.
FULLY VISIBLE one.To the eye, it appears
32°N–89°S as a 4th-magnitude orange ORION 5h 4h 3h
star, but a small telescope
CETUS
reveals a 10th-magnitude
FORNAX
companion, the white
dwarf.This is the easiest
white dwarf to spot with a 45
small telescope. It forms a 32
This large constellation represents a binary with a fainter red 17
river meandering from the foot of
Taurus south to Hydrus. Its range in dwarf, although this star
declination of 58 degrees is the
greatest of any constellation. may require a telescope
The only star of any note in with a slightly larger
Eridanus is 1st-magnitude Achernar,
or Alpha (α) Eridani, which lies at the aperture to be detectable. 64 39
southern tip of the constellation.The Two double stars of
name Achernar is of Arabic origin LEPUS NGC 1535
and means “river’s end”. note are Theta (θ) Eridani, 53
consisting of white stars of
Eridanus features in the story of 3rd and 4th magnitudes ERIDANUS
Phaethon, son of the sun god Helios,
who attempted to drive his father’s divisible through a small
chariot across the sky. He lost control
telescope, and 32 Eridani, a 54 NGC 1300
contrasting pair of orange
and blue stars of 5th and 6th 15
magnitudes, also within
range of a small telescope.
˚-30
˚-40 PHOENIX
HOROLOGIUM
CAELUM
Achernar
THE RIVER
THE NIGHT SKY CELESTIAL RIVER 2 NGC 1300 54
Eridanus has its source next to Rigel (in This is a classic example
Orion) and flows south to Achernar. It is of a barred spiral galaxy.
fully visible to almost all of the southern The length of its central
hemisphere and half of the northern. bar is greater than the
diameter of the Milky
Way, being 150,000
light-years across.
ORION 391
MONOCEROS
THE HARE SPECIFIC FEATURES Rigel ˚-10
Gamma (γ) Leporis is a 4th-magnitude RX
Lepus yellow star with a 6th-magnitude
orange companion, which is visible
SIZE RANKING 51 through binoculars.Another double star Sirius 17 R
is Kappa (κ) Leporis, a 4th-magnitude NGC 2017
BRIGHTEST STAR Arneb star with a close companion of 7th CANIS ERIDANUS
(α) 2.6 magnitude. It is difficult to separate MAJOR Arneb
through telescopes of small apertures. ˚-20
GENITIVE Leporis Adhara
NGC 2017 is a compact group Nihal
ABBREVIATION Lep of stars in what seems to be a chance
alignment.Thus it is not a true star LEPUS M79
HIGHEST IN SKY AT 10PM cluster at all.
January Near the border with Eridanus lies
R Leporis, an intensely red variable star
FULLY VISIBLE of the same type as Mira (in Cetus). Its
brightness ranges from 6th to 12th
62°N–90°S magnitude every 14 months or so.
The globular cluster M79 can be ˚-30
seen though a small telescope. In the
Lepus is often overlooked as it is same field of view lies Herschel 3752, CAELUM
surrounded by sparkling Orion and a triple star with components of 5th, 6h COLUMBA 5h
Canis Major, yet it is worthy of note. 7th, and 9th magnitudes.
It is one of the constellations known
to the ancient Greeks.
M79 15 THE HARE NGC 2017 5
This somewhat sparse 8th-magnitude This open cluster consists of a 6th-magnitude
globular cluster, 42,000 light-years away, star with four companions of 8th to 10th
has long starry arms which give it the magnitude, which are visible through a small
appearance of a starfish. telescope. Larger apertures reveal three
fainter stars in the group.
MYTHS AND STORIES THE NIGHT SKY
A RUNNING HARE
According to Greek mythology,
there were no hares on the island
of Leros until one man introduced
a pregnant female. Soon everyone
was raising hares, but they became
pests, destroying crops and reducing
the population to starvation.The
inhabitants eventually drove the
hares out of the island and put the
image of the hare among the stars
as a reminder that one can have
too much of a good thing.
THE HUNTER AND HUNTED
One of Orion’s dogs chases the hare in this
15th-century Flemish illustration, which was
based on the Liber Floridus of Lambertus,
compiled during the Middle Ages.
SAFE HAVEN 2
Lepus, the celestial hare, crouches under
the feet of Orion, like an animal trying to
hide from its hunter. Orion’s dogs, Canis
Major and Canis Minor, lie nearby.
the constellations
THE DOVE
Columba
SIZE RANKING 54
BRIGHTEST STAR
Phact (α) 2.7
GENITIVE Columbae
ABBREVIATION Col
HIGHEST IN SKY AT 10PM
January
FULLY VISIBLE
46°N–90°S
The Dutch theologian and astronomer THE DOVE BIRD WITH A MISSION 2
Petrus Plancius (see p.342) formed In this image, north is to the left and
this southern constellation in the MYTHS AND STORIES the stars of Puppis and Canis Major lie
late 16th century from stars near beneath Columba, the Dove, which
Lepus and Canis Major that had NOAH’S DOVE flies through the southern sky.
not previously been allocated to any
constellation. It supposedly represents In the Biblical story of the Flood,
Noah’s dove (see panel, right). Noah loaded an ark with a male and
female of every kind of animal on Earth.
SPECIFIC FEATURES It then rained for 40 days and 40 nights,
Fifth-magnitude Mu (μ) Columbae is drowning everything except the animals
a fast-moving star apparently thrown aboard the ark.When the rain abated,
out from the area of the Orion Noah sent out a dove to find dry land.
Nebula about 2.5 million years ago. The dove came back with an olive
Astronomers think that it was once a stem in its beak – a sure sign that
member of a binary system that was the waters were at last receding.
disrupted by a close encounter with
another star.The other member of WINGED MESSENGER
the former binary, moving away from The dove returns to Noah’s Ark, carrying an
Orion in the opposite direction, is olive branch, in this illustration by a 10th-
6th-magnitude AE Aurigae. century Catalan monk called Emeterio.
NGC 1851 is a modest globular
cluster that is visible as a faint patch
through a small telescope.
THE COMPASS
Pyxis
SIZE RANKING 65
BRIGHTEST STAR
Alpha (α) 3.7
GENITIVE Pyxidis
ABBREVIATION Pyx
HIGHEST IN SKY AT 10PM
February–March
FULLY VISIBLE
52°N–90°S
THE NIGHT SKY Pyxis is a faint and unremarkable THE
southern constellation lying next COMPASS
to Puppis on the edge of the Milky
Way. It represents a ship’s magnetic COMPASS
compass.The constellation was BEARINGS 2
introduced in the 18th century by In this image of the
the French astronomer Nicolas scattered stars of Pyxis,
Louis de Lacaille (see p.406). the Compass, north is on
the left, and the stars of
SPECIFIC FEATURES adjacent Puppis are to be
T Pyxidis is a recurrent nova – that found above Pyxis.
is, one that has undergone several
recorded outbursts. Five eruptions
have been seen since 1890, the last
being in 1966. During these outbursts,
it has brightened to 6th or 7th
magnitude. It is likely to brighten
again at any time and so become
visible through binoculars.
the constellations
THE STERN the 18th century. Puppis, representing of similar size to the full Moon. M46 NGC 2477 is an open cluster that
the ship’s stern, is the largest part.The is the richer of the two, while M47 is looks almost like a globular cluster
Puppis stars of each section retained their the closer, being about 1,500 light- when seen through binoculars, while
original Greek letters, and in the case years away – that is, less than one- NGC 2451 is more scattered and
SIZE RANKING 20 of Puppis the lettering now starts at third of the distance of its apparent has the 4th-magnitude orange giant
Zeta (ζ) Puppis, a star that is also neighbour.The cluster M93 lies about c Puppis near
BRIGHTEST STAR known as Naos. 3,500 light-years away. its centre.
Naos (ζ) 2.2 SPECIFIC FEATURES THE
GENITIVE Puppis Third-magnitude Xi (ξ) Puppis has STERN
a wide and unrelated 5th-magnitude
ABBREVIATION Pup companion that is visible through
binoculars, while k Puppis consists
HIGHEST IN SKY AT 10PM of a pair of nearly identical stars with
components of 5th magnitude that
January–February can be split through a small telescope.
FULLY VISIBLE L Puppis is a wide naked-eye and
binocular pair, of which L2 Puppis
39°N–90°S is a variable red giant that ranges
between 3rd and 6th magnitudes
This rich southern constellation every five months or so.
straddling the Milky Way was
originally part of the ancient Greek M46 and M47 are a pair of open
constellation of Argo Navis (the ship clusters that together create a brighter
of Jason and the Argonauts, see p.394) patch in the Milky Way. Both appear
until it was divided into three parts in
NGC 2477 15
This is one of the richest open clusters,
containing an estimated 2,000 stars. It is
about 4,000 light-years away. The star below
NGC 2477 in this picture – b Puppis – is
of magnitude 4.5.
STERN OF THE ARGO 2 SHARP CLUSTER 15 THE NIGHT SKY
The stars of Puppis, representing the M93 is an attractive open
stern of the Argo, are seen here rising cluster for viewing through
behind thin cloud. Sirius (in Canis Major) binoculars or a small
lies near the left edge of this picture. telescope. It is shaped like
an arrowhead with two
orange giants near its tip.
M46 AND NEBULA 15
A small planetary nebula,
seen here below centre,
seems to be part of M46 but
in fact lies in the foreground.
the constellations
THE SAILS UNDER SAIL 2
Vela represents the mainsail of the Argo, the
Vela ship of Jason and the Argonauts, sailing
through the southern sky in the quest for the
SIZE RANKING 32 golden fleece.
BRIGHTEST STAR THE EIGHT-BURST NEBULA 54
The planetary nebula NGC 3132 has loops of
Regor (γ) 1.8 gas that interlock like figures of eight, hence
GENITIVE Velorum the object’s popular name.
ABBREVIATION Vel
HIGHEST IN SKY AT 10PM
February–April
FULLY VISIBLE
32°N–90°S
In the 18th century, the ancient wider companions, with components
Greek constellation Argo Navis (the of 8th and 9th magnitudes, are visible
ship of Jason and the Argonauts – see through a telescope.
panel, below) was divided into three
parts, one of which was Vela, which IC 2391 is the best star cluster in
represents the ship’s sails. Because the Vela for the naked eye or binoculars.
stars labelled Alpha (α) and Beta (β) It is a group of several dozen stars
in the former Argo Navis are now in covering a greater area than the full
Carina, to the south, the labelling of Moon.To the north of it is another
the stars in Vela starts with Gamma (γ) binocular cluster, IC 2395.
Velorum, or Regor (see p.249).
NGC 2547 is an open cluster half
Between Gamma and Lambda (λ) the size of the full Moon and can be
Velorum are found the gaseous identified through binoculars or a
strands of the Vela supernova remnant small telescope.
(see p.265) – the supernova could
have been seen from Earth around Popularly known as the Eight-
11,000 years ago – while Delta (δ) Burst Nebula, NGC 3132 has
and Kappa (κ) Velorum combine with complex loops that are revealed only
two stars in Carina to form the False through a large telescope or on long-
Cross (sometimes mistaken for the exposure photographs. A small
true Southern Cross). telescope will show the nebula’s disc,
of similar apparent size to Jupiter, and
the 10th-magnitude star at its centre.
SPECIFIC FEATURES THE SAILS
Gamma Velorum is the brightest
example of a Wolf–Rayet star, a rare
type of star that has lost its outer
layers, thereby exposing its ultra-hot
interior. A 4th-magnitude companion
is visible through a small telescope
or good binoculars. In addition, two
MYTHS AND STORIES
THE ARGONAUTS
The Argo was a mighty 50-oared
galley in which Jason and 50 of
the greatest Greek heroes, called
the Argonauts, sailed to Colchis,
on the eastern shore of the Black
Sea, on their mission to fetch the
golden fleece of a ram.Their epic
voyage is one of the great stories
of Greek myth.
LEGENDARY SAILING GALLEY
The Argo, ship of the Argonauts, is here
depicted by the Italian artist Lorenzo Costa
(1459–1535).
THE NIGHT SKY IC 2391 21
Omicron (ο) Velorum, at magnitude 3.6, is
the brightest member of IC 2391, a scattered
cluster that lies some 500 light-years from
Earth in the southern reaches of Vela.
THE KEEL
Carina
SIZE RANKING 34 THE KEEL
BRIGHTEST STAR
Canopus (α) -0.6
GENITIVE Carinae
ABBREVIATION Car
HIGHEST IN SKY AT 10PM
January–April
FULLY VISIBLE
14°N–90°S
Carina is a major southern unusual variable star that flared up
constellation that was originally part during the 19th century to become
of the larger figure of Argo Navis, temporarily the second-brightest star in
which depicted a ship, until that was the sky, although it has now subsided to
split up in the 18th century. Carina around 5th magnitude. A shell of gas
represents the ship’s keel. around Eta, which was thrown off
during the outburst, is visible through a
Its most prominent star, Canopus, telescope, next to the Keyhole Nebula,
or Alpha (α) Carinae, is a white which appears as a dark and bulbous
supergiant 310 light-years away and cloud of dust silhouetted against the
second in brightness only to Sirius in glowing gas of the Carina Nebula.
the entire sky.The stars Epsilon (ε)
and Iota (ι) Carinae form a pseudo A glorious sight through binoculars,
“southern cross”, known as the False another treasure is IC 2602, an open
Cross, in conjunction with two stars cluster known as the Southern Pleiades.
in neighbouring Vela. Twice the apparent size of the full
Moon, it contains several stars visible to
SPECIFIC FEATURES the naked eye – the brightest being
Splashed across the Milky Way near 3rd-magnitude Theta (θ) Carinae.
the border with Centaurus and Vela is
the Carina Nebula, NGC 3372 (see Among Carina’s naked-eye clusters
p.245), a patch of glowing gas four is NGC 3532. At its widest point, this
diameters of the full Moon wide. It is elongated group of stars is twice the
visible to the eye and well seen width of the full Moon. NGC 3114 is
through binoculars.The densest and about the same apparent size as the full
brightest part of the nebula is around Moon, its brightest individual members
Eta (η) Carinae (see p.258), an being visible through binoculars. NGC
2516 is sparser and appears cross-shaped
through binoculars. Its brightest star is a
5th-magnitude red giant.
ELONGATED CLUSTER 1
What appears to be the brightest member
of NGC 3532, in the lower left of this
photograph, is in fact an extremely luminous
background star some four times farther off.
THE CARINA NEBULA 215
The brightest part of this immense cloud of
glowing gas is V-shaped (shown here), while
the star Eta (η) Carinae itself (below left of
centre) is a peculiar variable that appears as
a hazy orange ellipse.
EVEN KEEL 2 THE NIGHT SKY
Carina represents the keel and hull of
the Argonauts’ ship, the Argo. The
blade of the steering oar is marked
by Canopus, Carina’s brightest star.
the constellations
THE SOUTHERN CROSS supergiant that contrasts with the THE SOUTHERN CROSS
blue-white sparkle of the other stars,
Crux producing a resemblance to a casket
of jewels, hence the popular name.
SIZE RANKING 88
The Coalsack Nebula is to be
BRIGHTEST STARS Acrux found beside the Jewel Box.This dark
(α) 0.8, Becrux (or cloud of dust blocks light from the
Mimosa) (β) 1.3 stars of the Milky Way behind it. It
GENITIVE Crucis spans the width of 12 full Moons and
extends into neighbouring Centaurus
ABBREVIATION Cru and Musca, so is prominent to the
naked eye and through binoculars.
HIGHEST IN SKY AT 10PM
April–May
FULLY VISIBLE
25°N–90°S
Crux lies in a rich area of the Milky SIGN OF THE CROSS 2
Way. Although it is the smallest Four prominent stars make up the
constellation, it is instantly recognizable Southern Cross, one of the most famous
and is squeezed between the legs of of all celestial patterns, which appears
the centaur, Centaurus.The longer on the flags of several nations.
axis of the Southern Cross, as Crux
is known, points towards the south EXPLORING SPACE
celestial pole. Its stars were known
to the ancient Greeks (see panel, REDISCOVERING STARS
below), who regarded them as part
of Centaurus.They were made When European seafarers returned from
into a separate constellation in exploring the southern latitudes in the 15th
the 16th century. and 16th centuries, they reported stars they
had never seen before. Among these
SPECIFIC FEATURES
Alpha (α) Crucis or Acrux is the explorers was Amerigo Vespucci (1454-
most southerly first-magnitude star. 1512), an Italian who in 1501 charted
It is a glittering double that is readily Alpha (α) and Beta (β) Centauri and the
divisible through a small telescope.
The two components are of stars of Crux. Astronomers later realized
magnitudes 1.3 and 1.8. A wider 5th- that these stars had been known to the
magnitude star can be seen through ancient Greeks but that precession (see
binoculars; it is not related to Acrux. p.60) had subsequently carried them
below the horizon in Europe.
The star at the top of the cross is
the 2nd-magnitude red giant Gamma AMERIGO VESPUCCI
(γ) Crucis or Gacrux. It has an This imaginative view of Amerigo Vespucci
unrelated 6th-magnitude companion observing the Southern Cross with an astrolabe
visible through binoculars. Nearby, was painted by the 16th-century Flemish artist
Mu (μ) Crucis is a wide pair of Joannes Stradanus (Hans van der Straet).
4th- and 5th-magnitude stars easily
separated through a small telescope
or even good binoculars.
One of the gems of the southern
sky is the Jewel Box Cluster (see
p.288), or NGC 4755, visible to the
naked eye as a brighter patch within
the Milky Way near Beta (β) Crucis
or Becrux. Its individual stars, the
brightest being of 6th magnitude,
cover about one-third the width of
the full Moon.They can be viewed
through binoculars or a small telescope.
Near the centre is a ruby-coloured
THE NIGHT SKY THE COALSACK 21
The Coalsack Nebula, which lies next
to the stars of the Southern Cross, is
a smudgy cloud of interstellar dust
silhouetted against the bright
background of the Milky Way.
JEWELS OF THE SKIES 15
The Jewel Box Cluster is a sparkling
group of stars just north of the
Coalsack Nebula although the cluster
is almost ten times more distant
from the Earth.
THE FLY the constellations
Musca FINDING THE FLY 2
The long axis of the Southern Cross
SIZE RANKING 77 NGC 4833 15 points to Musca, the fly, which lies on
This globular cluster is the edge of the Milky Way within the
BRIGHTEST STAR just visible through southern celestial hemisphere.
binoculars. Individual
Alpha (α) 2.7 stars can be resolved THE
GENITIVE Muscae with a telescope of COMPASSES
100mm (4in) aperture.
ABBREVIATION Mus GEOMETRIC SHAPE 2
Circinus forms a slim
HIGHEST IN SKY AT 10PM triangle of stars and is
squashed into a sliver of
April–May the southern sky next to
the brilliant Alpha (α)
FULLY VISIBLE and Beta (β) Centauri.
14°N–90°S
This modest constellation is to be THE FLY
found in the Milky Way south of
Crux and Centaurus. In fact, the
southern tip of the dark Coalsack
Nebula extends into it from Crux.
Musca is one of the southern
constellations introduced at the end
of the 16th century by the Dutch
navigator-astronomers Pieter
Dirkszoon Keyser and Frederick
de Houtman. It represents a fly.
SPECIFIC FEATURES
Theta (θ) Muscae is a double star
with components of 6th and 8th
magnitude, divisible through a small
telescope.The fainter component is
an example of a Wolf–Rayet star – a
hot star that has lost its outer layers.
Musca also has a globular cluster,
known as NGC 4833 (see p.289).
THE COMPASSES
Circinus
SIZE RANKING 85
BRIGHTEST STAR
Alpha (α) 3.2
GENITIVE Circini
ABBREVIATION Cir
HIGHEST IN SKY AT 10PM
May–June
FULLY VISIBLE
19°N–90°S
Circinus represents a pair of dividing THE NIGHT SKY
compasses, as used by surveyors and
navigators. It is one of the figures
introduced in the 18th century by the
French astronomer Nicolas Louis de
Lacaille (see p.406).
This small southern constellation
is squeezed awkwardly in between
Centaurus and Triangulum Australe.
It lies next to Alpha (α) Centauri, so
it is not difficult to locate.
SPECIFIC FEATURES
Circinus contains little of interest for
amateur astronomers. Alpha (α)
Circini, however, is its one star of
note. It is situated against the
background of the Milky Way and is
easy to identify, being a double with
components of 3rd and 9th
magnitudes.These are divisible
through a small telescope.
the constellations
THE SET SQUARE
Norma
SIZE RANKING 74
BRIGHTEST STAR
Gamma-2 (γ2) 4.0
GENITIVE Normae
ABBREVIATION Nor
HIGHEST IN SKY AT 10PM
June
FULLY VISIBLE
29°N–90°S
Norma was introduced in the 1750s NGC 6067 15
by the Frenchman Nicolas Louis de This rich cluster covers
Lacaille (see p.406), and was originally an area of sky about
known as Norma et Regula, the square half the apparent
and ruler. It is an unremarkable diameter of the full
southern constellation lying in the Moon. It is seen
Milky Way between Lupus and the against the
zodiacal constellation of Scorpius. backdrop of the
Milky Way.
The stars that Lacaille designated
Alpha (α) and Beta (β) have since
been incorporated into Scorpius.
SPECIFIC FEATURES RIGHT ANGLE 2 THE
At magnitude 4.0, Gamma-2 (γ2) Norma’s most distinctive feature is a SET SQUARE
Normae is the constellation’s brightest right-angled trio of three faint stars,
star, and it is one-half of a naked-eye which is somewhat difficult to identify
double together with Gamma-1 (γ1) among the rich Milky Way star fields.
Normae, of magnitude 5.0.The two
stars lie at widely different distances
and hence are unrelated.
Two other doubles in the
constellation that are readily separated
through a small telescope are Epsilon
(ε) Normae, with components of 5th
and 7th magnitudes, and Iota-1 (ι1)
Normae, with components of 5th and
8th magnitudes.
NGC 6087 is a large open cluster
that has radiating chains of stars,
which are visible through binoculars.
Near its centre is its brightest star,
S Normae – a Cepheid variable that
ranges in brightness from magnitude
6.1 to 6.8 every 9.8 days.
THE NIGHT SKY THE SOUTHERN TRIANGLE Although smaller than its northern SOUTHERN TRIPLET 2
counterpart,Triangulum, this Triangulum Australe is an easily recognized
Triangulum Australe constellation contains brighter stars triangle of stars, lying in the Milky Way near
and so is more prominent. brilliant Alpha (α) and Beta (β) Centauri,
SIZE RANKING 83 which here are visible on the right.
SPECIFIC FEATURES
BRIGHTEST STAR NGC 6025 lies on THE SOUTHERN
Triangulum TRIANGLE
Alpha (α) 1.9 Australe’s northern
GENITIVE Trianguli border with Norma.
Australis It is 2,700 light-years
ABBREVIATION TrA away from the Earth.
This open cluster is
HIGHEST IN SKY AT 10PM noticeably elongated in
shape and is about one-
June–July third the apparent diameter
of the full Moon. It is easily
FULLY VISIBLE seen through binoculars.
19°N–90°S Alpha (α) Trianguli
Australis is an orange giant
Triangulum Australe is one of the whose colour shows
constellations of the southern sky prominently through
that was introduced at the end of the binoculars.
16th century by the Dutch navigators
Pieter Dirkszoon Keyser and There is nothing else in
Frederick de Houtman. It is the the constellation to attract
smallest of the 12 they identified. users of small telescopes.
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