The constellations in tonight’s sky host many familiar star patterns. For northern observers, autumn is the best time of the year to see Cassiopeia’s W, the Segment of Perseus, and the Great Square of Pegasus. These three bright asterisms are high above the horizon in the evening.
For observers in the southern hemisphere, the Southern Birds constellations Phoenix, Grus (the Crane), and Tucana (the Toucan) appear high overhead. They occupy the area between two first-magnitude stars, Fomalhaut in Piscis Austrinus (the Southern Fish) and Achernar in Eridanus (the River).
The night sky tonight looks different depending on the location. The constellation maps below show the sky at around 10 pm in the mid-northern, equatorial, and mid-southern latitudes.
Northern hemisphere
For northern observers, the sky overhead is dominated by three bright asterisms. These star patterns are the most visible parts of the three constellations associated with the myths of Andromeda and Perseus: Perseus, Cassiopeia, and Pegasus.
The largest of these asterisms, the Great Square of Pegasus, outlines the main body of the celestial Winged Horse. It is formed by three Pegasus stars – Scheat, Markab, and Algenib – and Alpheratz, the luminary of the neighbouring Andromeda. The asterism can be used to identify the two less conspicuous zodiac constellations in the vicinity: Pisces (the Fishes) and Aquarius (the Water Bearer).
Tonight’s sky as seen from mid-northern latitudes, image: Stellarium
The W of Cassiopeia is visible throughout the year for observers in the northern hemisphere. Formed by the five brightest stars of Cassiopeia, the asterism lies in a rich field of the Milky Way and can be used to locate the many well-known deep sky objects that appear in this region of the sky. These include the Heart and Soul nebulae (Sh2-190 and Sh2-199), the Double Cluster (NGC 869 and NGC 884), the Owl Cluster (NGC 457), the Pacman Nebula (NGC 281), the Bubble Nebula (NGC 7635), and the open clusters Messier 103 and Messier 52.
A line drawn from Gamma Cassiopeiae, the central star of the W, through Ruchbah, the bottom left star, leads to the Segment of Perseus, the identifying feature of the constellation Perseus. The asterism appears as a curved line of relatively bright stars that extends from the W in the direction of the bright Capella in the constellation Auriga (the Charioteer).
Mirfak, the brightest star in Perseus, is part of the Segment. It is also the central star in the Alpha Persei Cluster, an open cluster bright enough to be visible without binoculars.
The constellation Andromeda appears between the Segment of Perseus and the Square of Pegasus. Its brightest star, Alpheratz, is part of the Pegasus asterism. It is one of three bright stars that form a chain that stretches from the Great Square in the direction of Perseus. The equally bright Mirach, the central star in the chain, is commonly used to find the two most distant deep sky objects visible to the unaided eye: the Triangulum Galaxy (M33) and the Andromeda Galaxy (M31).
The constellation Triangulum (the Triangle) appears below the chain of Andromeda’s brightest stars. Its main constellation pattern, an elongated triangle, is easily visible on a clear night.
The zodiac constellation Aries (the Ram) can be identified by its three bright stars that form a flat triangle just below Triangulum.
The larger Pisces also appears high overhead at this time of the year. The heads of the two fishes can be found using the Great Square of Pegasus. The head of the brighter western fish is outlined by an asterism known as the Circlet of Pisces. The head of the eastern fish is far less conspicuous. It appears near Mirach in Andromeda.
Eastern sky
The constellations of the Winter Circle rise in the east in the evening. The Winter Circle (or Winter Hexagon) is the brightest seasonal asterism in the sky. It is formed by six first-magnitude stars: Sirius in Canis Major, Procyon in Canis Minor, Pollux in Gemini, Capella in Auriga, Aldebaran in Taurus, and Rigel in Orion. Sirius rises a bit later in the evening, but the other five stars are well above the horizon by 10 pm.
Orion is the most identifiable constellation in the eastern sky. Its crooked hourglass pattern is formed by Betelgeuse, Saiph, Rigel, and Bellatrix. At the centre, the bright Alnitak, Alnilam and Mintaka form the Belt of Orion, one of the best-known asterisms in the night sky.
Eastern sky in the northern hemisphere, image: Stellarium
A line extended from Orion’s Belt leads to Aldebaran, the brightest star in Taurus (the Bull). Aldebaran appears as the brightest star in the V-shaped Hyades cluster, which outlines the head of the celestial Bull. The giant star is not really a member of the cluster, but it lies in the same line of sight and marks the Bull’s eye.
Extending the line further from Aldebaran leads to the Pleiades, the most conspicuous open cluster in the night sky. The cluster appears as a bright bunch of grapes and is easily visible without binoculars even from light-polluted areas. It marks the Bull’s shoulder.
Elnath, the star that marks the Bull’s northern horn, is part of Auriga’s hexagon. The hexagon is a bright circle of stars that form the constellation pattern of the celestial Charioteer. The bright stars of Auriga can be used to find three bright open clusters: Messier 36, Messier 37, and Messier 38. Capella, the sixth brightest star in the sky, is part of the hexagon pattern.
Castor and Pollux mark the heads of the Twins (Gemini). Castor appears on the imaginary line extended from Rigel through Betelgeuse, and the slightly brighter Pollux lies just below Castor. Even though the two stars appear similar to the unaided eye, they are strikingly different. Castor is a sextuple star system about 50 light-years away, while Pollux is an evolved giant star 33.78 light-years away.
Northern sky
The northern sky is dominated by the two bear constellations, Ursa Major (the Great Bear) and Ursa Minor (the Little Bear), and Draco, the celestial Dragon. Cepheus (the King) and Camelopardalis (the Giraffe) appear higher in the sky.
The Great Bear, the third largest constellation in the sky (after Hydra and Virgo), appears low above the northern horizon. Its most visible feature, the Big Dipper, can be used to find the fainter constellations in the vicinity. Merak and Dubhe, the outer stars of the Dipper’s bowl, point toward Polaris, the star at the end of the Little Dipper’s tail.
Northern sky in the northern hemisphere, image: Stellarium
Polaris, the North Star, always appears directly north. It is the brightest star in the Little Dipper, but shining at magnitude 1.98, it barely makes the list of the 50 brightest stars in the sky. Kochab and Pherkad, the outer stars of the Little Dipper’s bowl, are known as the Guardians of the Pole because they circle close to the North Star. The middle four stars of the Little Dipper are quite faint and hard to see from light-polluted areas.
Draco is the eighth largest constellation in the sky, but it is not very conspicuous. The constellation’s most distinctive feature is an asterism known as the Lozenge or the Head of Draco. It can be found using the bright stars of the Northern Cross in Cygnus (the Swan).
A line extended through the beam of the Cross leads to Eltanin and Rastaban, the stars that mark the Dragon’s eyes. They are the two brighter stars in the Dragon’s head.
The Dragon’s tail can be made out between the Big and Little Dippers, and the rest of its body curves around the Little Dipper’s bowl in the direction of Cepheus.
The stars of Cepheus are not particularly bright, but the constellation figure of the King is easily recognizable because it resembles the pattern of a stick house. Alderamin, the constellation’s brightest star, can be found by extending a line from Schedar through Caph, the stars at the brighter end of Cassiopeia’s W.
Camelopardalis (the Giraffe) appears in the area between Cepheus and Auriga but is difficult to see in less-than-ideal conditions. The constellation’s brightest star, the yellow supergiant Beta Camelopardalis, shines at magnitude 4.02.
Western sky
Two large and prominent constellations set in the western sky in the evening. Pegasus (the Winged Horse) is high above the horizon, while Cygnus (the Swan) appears more to the northwest.
The Great Square of Pegasus can be used to find the bright globular cluster Messier 15 and the unbarred spiral galaxy NGC 7331. The Northern Cross in Cygnus serves as a guide to the open clusters Messier 29 and Messier 39, as well as to the several bright, large nebulae in this area of the sky. These include the North America Nebula (NGC 7000) and Pelican Nebula (IC 5070) near Deneb, the Sadr Region (IC 1318) at the centre of the Northern Cross, and the Veil Nebula (Caldwell 33 and 34), a large supernova remnant near Aljanah at the Swan’s wing.
Western sky in the northern hemisphere, image: Stellarium
The zodiac constellations Pisces and Aquarius appear in the southwest. They are relatively faint but contain asterisms that can be used to identify them.
The Circlet of Pisces, representing the head of the western fish, lies below the imaginary line connecting Algenib and Markab, the southern stars of the Great Square of Pegasus.
The Y-shaped Water Jar in Aquarius is found below the line connecting Markab at the western corner of the Great Square and the supergiant Enif, the brightest star in Pegasus.
The faint Equuleus (the Little Horse) appears between Enif and the western horizon at this time of the year. Vulpecula (the Fox), the home of the bright Dumbbell Nebula (Messier 27), lies next to the Swan’s beak, marked by Albireo at the bottom of the Northern Cross.
Altair and Vega, the bright stars that form the Summer Triangle with Deneb, set around 10 pm.
The small but distinctive Delphinus (the Dolphin) and Sagitta (the Arrow) are easy to make out low above the western horizon. Delphinus appears in the region between Enif and Albireo, and Sagitta lies between Albireo and Altair, the stars that mark the heads of their respective birds (the Swan and the Eagle).
Southern sky
Three large constellations associated with water appear above the southern horizon in the evening: Pisces (the Fishes), Cetus (the Sea Monster), and Eridanus (the River). The fainter Aquarius (the Water Bearer) and Piscis Austrinus (the Southern Fish) set in the southwest after 10 pm.
Pisces, the 14th largest of the 88 constellations, appears high in the sky next to the Square of Pegasus. Cetus, the fourth largest constellation, lies directly south. Diphda, the constellation’s brightest star, appears in the tail of the Sea Monster and Menkar, the second brightest star, appears in its head.
Menkar and the head of Cetus can be found using the bright V-shaped Hyades cluster as a pointer. Diphda is the brightest star northeast of the first-magnitude Fomalhaut, the star that marks the mouth of the Southern Fish (Piscis Austrinus).
Southern sky from the northern hemisphere, image: Stellarium
The faint Sculptor appears in the area south of Diphda and east of Fomalhaut. The constellation is a challenging target in urban areas. Its brightest star, the hot blue giant Alpha Sculptoris, has an apparent magnitude of 4.30. It is one of only five stars in the constellation that are brighter than magnitude 5.0.
Sculptor hosts the Sculptor Galaxy (NGC 253), one of the brightest galaxies in the sky. The galaxy appears in the area between Alpha Sculptoris and Diphda in Cetus.
Representing the celestial River, Eridanus stretches from Cursa near Rigel in Orion to Achernar in the far southern sky. Achernar stays below the horizon for most northern observers, but most of the constellation is visible low in the southern and southeastern sky.
The faint Fornax (the Furnace) makes an appearance above the southern horizon in the evening. However, with only one star brighter than magnitude 4.0, the constellation is a challenging target. Its brightest star, the F-type subgiant Dalim (Alpha Fornacis), shines at magnitude 3.85.
Equatorial latitudes
Observers in equatorial latitudes see many of the same constellations as those in the mid-northern locations, but these constellations do not appear in the same place. Additionally, observers near the equator can see many constellations in the southern sky that are invisible to northern observers.
Pisces (the Fishes), Cetus (the Sea Monster), and Eridanus (the River) – the constellations that appear above the southern horizon for northern observers – are high overhead in the evening when seen from equatorial latitudes. Cetus is the fourth largest constellation in the sky, Eridanus the sixth, and Pisces the 14th.
Tonight’s sky as seen from equatorial latitudes, image: Stellarium
The stars of Pisces are not particularly bright. The constellation’s luminary, the yellow giant Alpherg (Eta Piscium), shines at magnitude 3.61 and does not stand out in the sky. It can be identified using the brighter stars of the neighbouring Aries (the Ram). A line extended from Hamal through Sheratan points to Alpherg. The large spiral galaxy Messier 74 (the Phantom Galaxy) appears only 1.5 degrees east-northeast of the star.
Like Pisces, Cetus is not very conspicuous in the sky despite its size. Its two brightest stars, Diphda and Menkar (Beta and Alpha Ceti) lie at opposite ends of the constellation. Diphda marks the tail of the Sea Monster and Menkar marks its nostril. Diphda can be used to find the bright Sculptor Galaxy (NGC 253) and Menkar appears in the same area as the Squid Galaxy (Messier 77).
Eridanus (the River) extends farther from north to south than any other constellation. The A-type giant Cursa (Beta Eridani) is at the River’s northern end, near Rigel in Orion, and Achernar, the ninth brightest star in the sky, marks its southern end. At this time of the year, Cursa appears high in the eastern sky and Achernar is high above the southern horizon.
Northern sky
Cassiopeia (the Queen) is the most prominent constellation in the northern sky. Its five brightest stars form a conspicuous W or M. The Queen’s constellation figure can be used to find the fainter King (Cepheus). Cepheus appears between Cassiopeia and the northern horizon in the evening. It can be recognized by the stick house pattern formed by its brightest stars.
Alderamin, the brightest star in Cepheus, can be found by extending a line from Schedar through Caph, the two brightest stars in Cassiopeia. Alderamin is the brightest star along this imaginary line and it appears at the base of the house asterism.
Northern sky from equatorial latitudes, image: Stellarium
The faint Camelopardalis (the Giraffe) appears east of Cassiopeia and Cepheus, but is a difficult constellation to see from urban areas. Its brightest star, the yellow supergiant or bright giant Beta Camelopardalis, shines at magnitude 4.02.
Pegasus dominates the northwestern sky. Representing the mythical winged horse, Pegasus is the seventh largest constellation in the sky. Even though it does not contain any first-magnitude stars, it is easy to spot because three of its bright stars – Scheat, Markab, and Algenib – form the Great Square of Pegasus with Alpheratz in the constellation Andromeda (the Princess).
Alpheratz (Alpha Andromedae) was once considered to be part of both Andromeda and Pegasus. It had the Bayer designation Delta Pegasi. Its other traditional name, Sirrah, comes from the Arabic phrase meaning “the navel of the horse.” The star now belongs only to Andromeda.
Alpheratz forms a chain with the equally bright Mirach and slightly fainter Almach that stretches from the Square of Pegasus in the direction of Perseus. Mirach, the central star in the chain, can be used to find the Andromeda Galaxy (M31) and the Triangulum Galaxy (M33). The three bright Andromeda stars also make a good starting point for finding the smaller constellation figures of Triangulum (the Triangle) and Aries (the Ram).
Perseus occupies much of the sky between Cassiopeia’s W and the bright Aldebaran in Taurus (the Bull). Its most prominent feature is the Segment of Perseus, a curving line of stars that begins southeast of Cassiopeia and extends in the direction of Taurus and Auriga (the Charioteer).
Eastern sky
Several of the brightest stars in the sky rise in the east in the evening. Six of them form the Winter Hexagon, the brightest asterism in the sky: Sirius, Procyon, Pollux, Capella, Aldebaran, and Rigel.
Sirius, the luminary of Canis Major (the Great Dog), is the brightest star in the night sky. Shining at magnitude -1.46, it is one of our nearest neighbours. It lies only 8.60 light-years away.
Sirius is found along the imaginary line extended from the three bright stars of Orion’s Belt to the southeast. Alnitak, Alnilam, and Mintaka, the stars of Orion’s Belt, also point in the direction of Aldebaran, the brightest star in Taurus and the 14th brightest star in the sky.
Eastern sky from equatorial latitudes, image: Stellarium
Aldebaran marks one of the Bull’s eyes and appears in the same line of sight as the Hyades, a bright V-shaped open cluster that represents the Bull’s head. Ain, the star that marks the Bull’s other eye, is a member of the cluster. Aldebaran is not. The Pleiades cluster lies farther down the line extended from Orion’s Belt.
The Orion’s Belt stars make it easy to identify the rest of the constellation Orion. Rigel, Betelgeuse, Bellatrix, and Saiph outline Orion’s hourglass pattern. Three of these stars are supergiants (all except Bellatrix). Three – Rigel, Bellatrix, and Saiph – are hot blue B-type stars, while Betelgeuse is a cool red supergiant. Rigel and Betelgeuse, Orion’s brightest stars, are the seventh and tenth brightest stars in the sky.
Rigel and Saiph, the stars that mark the knees of Orion, can be used to find Lepus (the Hare), and a line drawn from Rigel through Betelgeuse points in the direction of Gemini. Castor and Pollux, the stars that mark the Twins’ heads, are the 23rd and 17th brightest stars in the sky.
Rigel can also be used to find the constellation Eridanus (the River), which extends from Orion far into the southern sky. Cursa, the constellation’s second brightest star, marks the northern end of the River, while Achernar, the brightest star in Eridanus and the ninth brightest star in the sky, marks the southern.
Auriga (the Charioteer) dominates the northeastern sky. Capella, the constellation’s brightest star, is the sixth brightest star in the sky.
The brightest stars of Auriga form a hexagon pattern that makes the constellation easy to identify even from urban areas. Elnath (Beta Tauri), the southernmost star in the asterism, is not part of the Auriga constellation. It marks the northern horn of the celestial Bull. Tianguan (Zeta Tauri), the star that represents the Bull’s southern horn, can be used to find the bright supernova remnant Messier 1, also known as the Crab Nebula.
Western sky
The zodiac constellations Aquarius and Capricornus occupy much of the western sky. Pegasus lies high in the northwest and the faint Equuleus (the Little Horse) appears near Enif, the bright star that marks the muzzle of Pegasus.
Enif is not part of the Great Square of Pegasus, the asterism that makes the constellation recognizable. The star appears about halfway between the Great Square and the western horizon in the evening.
Western sky from equatorial latitudes, image: Stellarium
A line extended through the western stars of the Great Square across the sky leads to Fomalhaut, the brightest star in Piscis Austrinus (the Southern Fish) and the 18th brightest star in the sky. Most of the constellation Aquarius lies within the triangle formed by Fomalhaut, Enif, and Markab at the southwestern corner of the Great Square.
Aquarius (the Water Bearer) and Capricornus (the Sea Goat) do not stand out in the sky. Their brightest stars, the supergiant Sadalsuud (Beta Aquarii) and giant Deneb Algedi (Delta Capricorni), shine at magnitudes 2.87 and 2.81.
Sadalsuud, its neighbour Sadalmelik, and Enif in Pegasus are similar stars. The three supergiants are believed to have been formed in the same molecular cloud. They form an asterism known as the Lightning Bolt with Deneb Algedi at the Sea Goat’s tail. The asterism makes it easy to identify the luminaries of Aquarius and Capricornus.
Southern sky
Three first-magnitude stars appear in the southeastern, southern, and southwestern sky. Canopus, the brightest star in Carina (the Keel) and the second brightest star in the sky, lies above the southeastern horizon. Achernar, the luminary of Eridanus (the River) and the ninth brightest star in the sky, appears almost directly south. Fomalhaut, the 18th brightest star in the sky, appears higher above the southwestern horizon. It marks the mouth of the Southern Fish (Piscis Austrinus).
Achernar marks the southern end of the celestial River (Eridanus). The rest of the constellation Eridanus winds across the sky in the direction of Orion (the Hunter).
Southern sky from equatorial latitudes, image: Stellarium
Achernar and Canopus can be used to find the fainter Pictor (the Painter’s Easel), Dorado (the Dolphinfish), and Reticulum (the Reticle). These constellations appear in the region between the two bright stars. The constellation figure of Hydrus (the Lesser Water Snake) lies south of Achernar, and Tucana (the Toucan) appears southwest of the star.
Hydrus and Tucana host the Small Magellanic Cloud (SMC), a dwarf galaxy that appears as a detached piece of the Milky Way on a clear night. It is one of our galaxy’s closest neighbours. The Large Magellanic Cloud (LMC) lies in the less conspicuous Dorado and Mensa (Table Mountain).
Tucana is one of the Southern Birds constellations, along with Grus (the Crane), Phoenix, and Pavo (the Peacock). These constellations dominate the southwestern sky in the evening. The brightest stars of Phoenix, Grus, and Pavo – Ankaa, Alnair, and Peacock respectively – are among the 58 stars selected for use in celestial navigation. The constellations themselves are not particularly bright but can be found using Achernar and Fomalhaut.
Southern hemisphere
The Southern Birds constellations Phoenix, Grus (the Crane), and Tucana (the Toucan) fly high overhead around 10 pm for observers in the mid-southern latitudes.
Ankaa, the brightest star in Phoenix, is named after the constellation. Its name comes from the Arabic word for “phoenix.” The orange giant shines at magnitude 2.377 from a distance of 82 light-years. The rest of the constellation Phoenix is much fainter. The yellow giant Beta Phoenicis, the constellation’s second brightest star, is almost a full magnitude fainter than Ankaa.
Grus (the Crane) is slightly brighter. Its luminary Alnair is a hot blue star with an apparent magnitude of 1.74, located 101 light-years away. The red giant Tiaki (Beta Gruis) is slightly fainter, shining at magnitude 2.146.
Tonight’s sky as seen from the southern hemisphere, image: Stellarium
The neighbouring Tucana does not contain any stars brighter than third magnitude. Its brightest star, the orange giant Alpha Tucanae (formally known as Lang-Exster), shines at magnitude 2.86. The constellation hosts 47 Tucanae, one of the brightest globular clusters in the sky, as well as most of the Small Magellanic Cloud.
Fomalhaut and Achernar are the brightest stars near the zenith in the evening. The faint Sculptor, the home of the bright Sculptor Galaxy (Caldwell 65, NGC 253), can be found in the area between the two stars, as can Phoenix and Grus. The other two Southern Birds, Tucana and Pavo, lie more to the south-southeast.
Fomalhaut, the brightest star in Piscis Austrinus (the Southern Fish), is an A-type main sequence star that shines at magnitude 1.16 from a distance of 25.13 light-years. It is one of the hottest stars in the solar neighbourhood. The star’s circumstellar disk of dust has earned it the nickname the Eye of Sauron.
Fomalhaut is found by extending a line from the western side of the Great Square of Pegasus. It is the only first-magnitude star that lies along this imaginary line. It appears isolated in this region of the sky.
Sculptor lies east of Piscis Austrinus but is a difficult target in light-polluted skies. The constellation’s brightest star, Alpha Sculptoris, has an apparent magnitude of 4.30. It can be used to find the Sculptor Galaxy (NGC 253) and the Claw Galaxy (NGC 247). The galaxies lie in the region between Alpha Sculptoris and Diphda at the tail of Cetus (the Sea Monster).
Northern sky
The constellations that occupy the sky above the northern horizon in the evening are Pegasus (the Winged Horse), Andromeda (the Princess), and Pisces (the Fishes). All three are ancient constellations, catalogued by the Greco-Roman astronomer Ptolemy in the 2nd century CE.
The Great Square of Pegasus dominates the northern sky. Formed by the Pegasus stars Algenib, Markab, and Scheat with Alpheratz in Andromeda, the star pattern is easy to spot even from light-polluted areas.
Enif, the brightest star in Pegasus, is not part of the asterism. It appears high above the northwestern horizon and can be used to find the bright globular cluster Messier 15. With an apparent magnitude of 6.2, the cluster can be observed in binoculars. It is one of the oldest known globular clusters in the Milky Way, with an estimated age of about 12 billion years.
Northern sky in the southern hemisphere, image: Stellarium
The four stars of the Great Square of Pegasus make it easy to find the Circlet of Pisces, an asterism outlining the head of the western fish in Pisces. The asterism appears high above the northern horizon around 10 pm.
Pisces is the 14th largest constellation in the sky, but it is quite faint and difficult to make out from urban areas. It is depicted as two fishes connected by two cords joined at an apex, marked by Alrescha (Alpha Piscium, mag. 3.82).
Alpherg (Eta Piscium), the brightest star in Pisces, is part of the northern cord. It shines at magnitude 3.6 from an approximate distance of 350 light-years. Gamma Piscium, the constellation’s second brightest star, has an apparent magnitude of 3.7 and is part of the Circlet of Pisces. Both Eta and Gamma Piscium are yellow giants much more luminous than the Sun.
Andromeda is easy to find because its three brightest stars form a chain that extends from the Great Square of Pegasus in the direction of Perseus. Alpheratz, the westernmost of these stars, is part of the Pegasus asterism and was once part of both constellations.
Mirach, the central star of the chain, is well-known to stargazers because it can be used to find the Andromeda Galaxy (Messier 31) and the Triangulum Galaxy (Messier 33). The galaxies appear on opposite sides of the star and both are visible to the unaided eye in good conditions.
Eastern sky
Orion (the Hunter), Lepus (the Hare), and Eridanus (the River) appear above the eastern horizon in the evening. The bright Taurus (the Bull) rises in the northeast and Canis Major (the Great Dog) appears south of Orion.
Orion is one of the most recognizable constellations in the sky, along with Ursa Major, Cygnus, Crux, and Cassiopeia. The figure of the celestial Hunter is outlined by seven bright stars. Betelgeuse and Bellatrix sit at Orion’s shoulders, Alnitak, Alnilam and Mintaka form Orion’s Belt, and Rigel and Saiph mark the Hunter’s knees or feet. All these stars except Betelgeuse are exceptionally hot and luminous blue giants and supergiants of the spectral types O and B.
Eastern sky in the southern hemisphere, image: Stellarium
Rigel and Betelgeuse are both first-magnitude stars, shining at magnitudes 0.13 and 0.50 from distances of 848 and 548 light-years respectively. Rigel is a hot blue supergiant and Betelgeuse is a cool red one. Both are variable stars and, even though Rigel is usually the brighter of the two, Betelgeuse occasionally takes over as the constellation’s brightest star.
Rigel can be used to find two less conspicuous nearby constellations: Eridanus and Lepus. Cursa, the second brightest star in Eridanus, appears near Rigel. The rest of the celestial River winds all the way to the far southern sky, where the bright Achernar marks its end.
The constellation Lepus lies at Orion’s feet. Lepus represents a hare chased by Orion and his two dogs, Canis Major and Canis Minor. The Hare’s ears appear below Rigel and its tail, below Saiph.
Canis Major sits low above the horizon around 10 pm. The constellation is home to Sirius, the brightest star in the sky and one of our closest neighbours. Popularly known as the Dog Star, Sirius shines at magnitude -1.46 from a distance of 8.60 light-years. It appears so bright both because of its proximity and its intrinsic brightness. It is an A-type main sequence star with a surface temperature of 9,940 K and a luminosity 25.4 times that of the Sun.
Taurus rises in the northeastern sky in the evening. The constellation is easy to recognize because it is home to the Pleiades and Hyades, the brightest and nearest open clusters in the sky. The Pleiades mark the Bull’s shoulder and the Hyades its head.
Aldebaran, the constellation’s brightest star, appears as a member of the Hyades (which it is not) and marks one of the Bull’s eyes. The star is easy to identify because it appears on the imaginary line extended from the three stars of Orion’s Belt.
Western sky
Sagittarius (the Archer) is the brightest constellation setting in the west in the evening. The Teapot asterism, formed by its brightest stars, appears next to the Scorpion’s tail and stinger. Scorpius has mostly set, but most of the stars that form the Fish Hook pattern can still be spotted around 10 pm.
Sagittarius is known for its many bright deep sky objects, including the nebulae M8 (the Lagoon Nebula), M17 (the Omega Nebula), and M20 (the Trifid Nebula). These and other objects can be found using the stars of the Teapot.
Western sky in the southern hemisphere, image: Stellarium
Scutum (the Shield) is one of the smallest and faintest constellations in the sky. Best known for being home to the variable star Delta Scuti and the Wild Duck Cluster (Messier 11), the constellation lies between the Teapot and the tail of Aquila (the Eagle).
Capricornus (the Sea Goat) appears higher above the horizon in the evening. The faint V-shaped pattern that dominates the constellation can be made out near Sagittarius on a clear night.
Southern sky
Crux, the most recognizable constellation in the southern celestial hemisphere, sits directly above the southern horizon in the evening. The constellation takes its name from its dominant star pattern, the Southern Cross.
The asterism is formed by Acrux (Alpha Crucis), Mimosa (Beta Crucis), Gacrux (Gamma Crucis), Imai (Delta Crucis), and Ginan (Epsilon Crucis). A line extended from Gacrux through Acrux points in the general direction of the south celestial pole, which lies in the faint constellation Octans (the Octant).
The Southern Cross is one of three cross asterisms in the far southern sky. The other two – the False Cross and the Diamond Cross – are fainter, but sometimes mistaken for the Southern Cross.
The easiest way to identify the real Southern Cross is to look for Rigil Kentaurus and Hadar (Alpha and Beta Centauri), the brightest stars in the constellation Centaurus (the Centaur). These stars are known as the Southern Pointers because they point toward Gacrux, the star at the top of the Southern Cross. At this time of the year, the asterism appears upside down in the evening.
Southern sky in the southern hemisphere, image: Stellarium
The fainter but distinctive Musca (the Fly) is easy to find because it appears near Acrux, and the small Circinus (the Compass) can be made out near Alpha Centauri.
Triangulum Australe (the Southern Triangle) is one of the more recognizable southern constellations. Like Crux, it is one of the smallest constellations in the sky, but the triangle that gives it its name stands out in the sky. It is formed by the second-magnitude Atria (Alpha Trianguli Australis) with the fainter Beta and Gamma Trianguli Australis.
The southeastern sky is occupied by the three constellations that once formed Argo Navis, the largest constellation in the sky. Named after the Greek mythical ship Argo, the constellation comprised Carina (the Keel), Vela (the Sails), and Puppis (the Stern).
Carina is the brightest of the three. Its three brightest stars – Canopus, Miaplacidus, and Avior – are navigational stars, bright and recognizable enough to be useful in the field of celestial navigation. Canopus itself is the second brightest star in the sky, after Sirius in Canis Major.
Canopus and Miaplacidus can be used to find the faint Volans (the Flying Fish) and Pictor (the Easel).
Miaplacidus is one of the four stars that form the Diamond Cross, along with Theta, Upsilon, and Omega Carinae. Avior is part of the False Cross, along with its Carina neighbour Aspidiske and the Vela luminaries Alsephina and Markeb.
The False Cross can be used to find the bright Omicron Velorum Cluster (IC 2391), the open clusters NGC 2516 and IC 2488, and the reflection nebula IC 2220.
The Diamond Cross serves as a guide to the Southern Pleiades (IC 2602), the famous Carina Nebula, the massive globular cluster NGC 2808, and the bright Lambda Centauri Nebula (IC 2944), popularly known as the Running Chicken Nebula.