The stars in tonight’s sky form many familiar patterns that make their host constellations easy to identify.
For observers in the northern hemisphere, Capella is the brightest star high overhead in the evening. The luminary of the constellation Auriga (the Charioteer) forms an asterism known as the Winter Circle or Winter Hexagon with five other first-magnitude stars: Rigel, Aldebaran, Pollux, Sirius, and Procyon. The stars of the Winter Circle appear high in the eastern and southeastern sky.
Observers in the southern hemisphere can see these stars in the northern and northeastern sky in the evening. Sirius and Canopus, the brightest stars in the sky, appear high above the horizon, and Achernar and Fomalhaut lie in the western and southwestern sky. The Southern Pointers, Alpha and Beta Centauri (Rigil Kentaurus and Hadar), and the stars of the Southern Cross dominate the southern and southeastern sky.
The stars visible tonight depend on the observer’s location and the time of night. The star maps below show the first and second magnitude stars visible in the night sky around 10 pm in the mid-northern, equatorial, and mid-southern latitudes.
Northern hemisphere
The brightest stars visible in the northern hemisphere in the evening are the stars of the Winter Hexagon and the Winter Triangle. The two bright seasonal asterisms appear high above the horizon in the evening.
The Winter Hexagon is formed by Sirius, the brightest star in the constellation Canis Major (the Great Dog), with Procyon in Canis Minor (the Little Dog), Rigel in Orion (the Hunter), Aldebaran in Taurus (the Bull), Capella in Auriga (the Charioteer), and Pollux in Gemini (the Twins).
Sirius, the Dog Star, is the brightest star in the sky. It forms a smaller asterism called the Winter Triangle with Procyon and Betelgeuse.
Sirius is an A-type main sequence star located only 8.60 light-years away. It is the seventh closest individual star to the Sun. It has twice the Sun’s mass and is 25.4 times more luminous. The star has a white dwarf companion, nicknamed the Pup.
Procyon is an older and more evolved F-type star located 11.46 light-years away. Shining at magnitude 0.34, it is the eighth brightest star in the sky. Like Sirius, it forms a binary star system with a white dwarf. Procyon is the fourth nearest star to the solar system that is visible to the unaided eye, after Alpha Centauri, Sirius, and Epsilon Eridani.
Stars visible tonight in the northern hemisphere, image: Stellarium
The bright stars of Orion appear high above the southern horizon in the evening. The supergiants Rigel and Betelgeuse, Orion’s brightest stars, are the seventh and 10th brightest stars in the sky.
Even though Rigel is usually brighter, it has the Bayer designation Beta Orionis, while the unpredictable Betelgeuse is known as Alpha Orionis. Both supergiants are variable stars, and Betelgeuse has been known to outshine Rigel, but only rarely. Both stars will end their lives as spectacular supernovae.
Capella appears close to the zenith around 10 pm. It is the sixth brightest star in the sky and the third brightest star in the northern celestial hemisphere, after Arcturus and Vega. The giant star is part of a multiple star system located 42.9 light-years away. It forms Auriga’s hexagon with the constellation’s other bright stars and with Elnath in the neighbouring constellation Taurus.
Aldebaran, the luminary of the Bull constellation, is the 14th brightest star in the sky. The giant lies 65.3 light-years away and marks one of the Bull’s eyes. It appears in the same line of sight as the Hyades, a bright, nearby open cluster that outlines the Bull’s V-shaped head.
Pollux and the slightly fainter Castor mark the heads of Gemini, the celestial Twins. Like Aldebaran, Pollux is an evolved K-type giant that has already entered the last stage of its life. It lies 33.78 light-years away and is the 17th brightest star in the sky.
Regulus, the brightest star in the constellation Leo, is the faintest first-magnitude star. Shining at magnitude 1.40, it is the 21st brightest star in the sky. The hot blue subgiant lies 79.3 light-years away and forms a triple star system with two fainter main sequence stars. Regulus marks the Lion’s heart and is part of an asterism called the Sickle of Leo.
Stars in the northern sky
There are no exceptionally bright stars appearing directly north around 10 pm. Deneb, the brightest star in Cygnus (the Swan), sets in the northwestern sky. It is the only first-magnitude star visible in this part of the sky in the evening.
Polaris, the luminary of the Little Bear constellation, always appears high in the northern sky for observers in the mid-northern latitudes. The supergiant star always appears in the same place from any given latitude while other stars appear to circle around it.
Polaris is currently the North Star, the nearest visible star to the north celestial pole. With an apparent magnitude of 1.98, it is on average the 48th brightest star in the sky. The supergiant has 5.4 times the Sun’s mass and a radius 37.5 times that of the Sun. It is 1,260 times more luminous than the Sun and shines at second magnitude from a distance of 323 – 433 light-years.
Polaris marks the tip of the Little Bear’s tail and the end of the Little Dipper’s handle. Formed by seven stars in the constellation Ursa Minor (the Little Bear), the Little Dipper is largely invisible from urban areas because its middle four stars are quite faint. The only other second-magnitude star in Ursa Minor is Kochab, one of the outer stars of the Little Dipper’s bowl. Kochab and the fainter Pherkad (the other outer star of the bowl) are called the Guardians of the Pole because they always circle closely around Polaris.
Stars in the northern sky tonight, image: Stellarium
Polaris, Kochab and Pherkad can be found using the stars of the brighter Big Dipper, which appears in the northeastern sky in the evening. Merak and Dubhe, the outer stars of the Big Dipper’s bowl, point in the general direction of the North Star. Kochab and Pherkad appear parallel to Alioth and Mizar, the inner stars of the Big Dipper’s handle.
The four stars that outline the head of the celestial Dragon (Draco) appear directly north. Eltanin and Rastaban, the stars that mark the Dragon’s eyes, appear close to the horizon. Eltanin, the constellation’s brightest star, is a class K giant located 154.3 light-years away.
The bright stars of Cassiopeia appear high in the northwestern sky. The constellation’s five brightest stars form Cassiopeia’s W, an asterism that may appear as an “M,” depending on the location and time of year and night. A line extended from Schedar through Caph points towards Alderamin, the only second-magnitude star in Cepheus.
Stars in the eastern sky
The brightest stars in the eastern sky are Regulus, Denebola and Algieba. These are the three brightest stars in the zodiac constellation Leo. Regulus and Algieba are part of the Sickle, an asterism that represents the Lion’s head and mane, while Denebola marks the Lion’s tail.
Regulus (Alpha Leonis) is the brightest component in a quadruple star system located approximately 79.3 light-years away. It is a hot blue subgiant star with 3.8 times the Sun’s mass and 316.2 times its luminosity.
Regulus is one of the fastest spinners visible to the unaided eye. With a projected rotational velocity of 318 km/s, it spins dangerously close to its breakup velocity. The star takes only 15.9 hours to complete a rotation. In comparison, the Sun takes about 25 days.
Regulus is an example of gravity darkening. The star has a flattened shape due to its high spin rate. Its poles are much brighter and hotter than the equator because they are closer to the star’s centre of mass.
Regulus can be used to find the fainter Alphard, the brightest star in Hydra (the Water Snake). Even though it is the largest of the 88 constellations, Hydra is not particularly conspicuous. Alphard is the only second-magnitude star in the constellation. It is a K-type bright giant or giant star located approximately 177 light-years away. The name Alphard comes from the Arabic word for “the individual,” referring to Alphard’s isolation. It is the only relatively bright star in this region of the sky.
Stars in the eastern sky tonight, image: Stellarium
Denebola is another fast spinner in Leo. It has a rotational velocity of 128 km/s and, like Regulus, it is flattened at the poles and has an equatorial bulge. Denebola is an A-type main sequence star located 35.9 light-years away.
Algieba is a more evolved star. It is an orange giant that forms a binary star system with a yellow giant. The two stars lie 130 light-years away. They take 510.3 years to complete an orbit around a common centre of mass. The primary component hosts a confirmed exoplanet, Gamma Leonis b, with a mass at least 8.78 times that of Jupiter.
Regulus can be found using the bright stars of the Big Dipper, which appear high in the northeastern sky. Megrez and Phecda, the inner stars of the Dipper’s bowl, point in the direction of the Lion’s heart. A line drawn from Megrez through Merak leads to Castor in the constellation Gemini (the Twins).
Six of the seven Big Dipper stars shine at second magnitude, making the asterism one of the most familiar patterns in the northern sky. Alkaid and Dubhe are over 100 light-years away, while the middle four stars are closer to us and belong to the same stellar family, the Ursa Major moving group.
These five stars – Alioth, Mizar, Megrez, Phecda and Merak – are of spectral type A and lie approximately 80 light-years away. Mizar, Phecda and Megrez are still on the main sequence, Merak is a subgiant, and Alioth, the brightest star in Ursa Major, is a giant.
In contrast, Dubhe is an orange giant and Alkaid is a hot blue main sequence star. Alkaid is the most massive of the seven stars, with a mass 6.1 times that of the Sun.
Stars in the western sky
The stars of Pegasus, Andromeda (the Princess), Pisces (the Fishes) and Cetus (the Whale) set in the west in the evening. Andromeda and Pegasus dominate the evening sky during the northern hemisphere autumn and set early in the winter.
Alpheratz connects the two constellations. The hot blue subgiant forms the Great Square of Pegasus with Scheat, Markab and the fainter Algenib in Pegasus. The asterism forms the main body of the celestial Winged Horse. However, Alpheratz does not belong to the constellation Pegasus but to the neighbouring Andromeda. It is part of a prominent chain of three bright stars that make the Princess constellation recognizable.
The three stars – Alpheratz, Mirach and Almach – appear equally bright. Mirach, the middle star, can be used to find the Andromeda Galaxy and the Triangulum Galaxy, the most distant deep sky objects visible to the unaided eye (in exceptionally good conditions).
Mirfak, the brightest star in Perseus, appears to extend the chain to the east. The supergiant is the central star in the Alpha Persei Cluster, an open cluster visible without binoculars. The famous variable star Algol forms a triangle with Mirfak and Almach.
Stars in the western sky tonight, image: Stellarium
Hamal, the brightest star in Aries (the Ram), appears almost directly west. The orange giant lies 65.8 light-years away. It forms a flat triangle with the fainter Sheratan and Mesarthim that makes Aries easy to identify on a clear night.
The faint stars of Cetus and Pisces occupy much of the western and southwestern sky. Even though they are among the largest constellations in the sky, Cetus and Pisces do not contain any exceptionally bright stars and do not stand out in the sky. Diphda, the only second-magnitude star in Cetus, has already set by 10 pm. Pisces only has two stars brighter than magnitude 4 and requires clear, dark skies to be made out.
Stars in the southern sky
The Winter Triangle dominates the southern sky in the evening. Formed by Sirius in Canis Major, Procyon in Canis Minor, and Betelgeuse in Orion, it is one of the brightest asterisms in the winter sky. The star pattern can be used to find several famous deep sky objects in the fainter constellation Monoceros (the Unicorn), including the Rosette Nebula with the Satellite Cluster and the Cone Nebula with the Christmas Tree Cluster.
Sirius and Procyon, the luminaries of the two dog constellations, are among our nearest neighbours. Sirius, the brightest star in Earth’s sky, is popularly known as the Dog Star. The star’s name comes from the Greek word for “scorching.” The name Procyon is also Greek in origin and means “before the dog.” It refers to the fact that Procyon rises before the brighter Sirius.
Betelgeuse is the brightest red supergiant in the sky and the second brightest star in Orion. With a mass of 14 – 19 solar masses, it is one of the brightest supernova candidates in the sky.
Betelgeuse was once considered to be the largest star known. Estimates of its size are in the range between 764 and 1,021 solar radii. The exact size of Betelgeuse is difficult to determine due to pulsations in the star’s atmosphere. The supergiant lies 548 light-years away and marks Orion’s shoulder.
Stars in the southern sky tonight, image: Stellarium
The brighter Rigel, one of the stars of the Winter Circle, is the seventh brightest star in the sky, while Betelgeuse is the 10th.
Rigel, a hot blue supergiant, appears in the Hunter’s leg. Like most other bright stars in Orion, it is a supernova candidate. It lies 848 light-years away and has a luminosity of 120,000 Suns.
The fainter Bellatrix, Saiph, the stars of Orion’s Belt, and the third magnitude Hatysa, which marks Orion’s Head, are all hot, luminous, massive O- and B-type stars that will live very short lives due to their high mass. Bellatrix is the only bright star in Orion that may not end its life as a supernova. With a mass 7.7 times that of the Sun, the star is on the threshold for a supernova candidate.
Rigel and Saiph can be used to find the fainter stars of the constellation Lepus (the Hare), which appear at Orion’s feet. The stars of Orion’s Belt point towards Aldebaran in Taurus in one direction and towards Sirius in the other.
Other than Sirius, the bright stars of Canis Major are also destined to go out as supernovae. The blue giant Adhara is the 22nd brightest star in the sky and the brightest second magnitude star. It forms a conspicuous triangle with the F-type supergiant Wezen and the B-type supergiant Aludra.
Mirzam, the bright star near Sirius, is a hot blue giant or bright giant that shone at magnitude -3.65 about 4.42 million years ago and was the brightest star in the sky. Similarly, Adhara had an apparent magnitude of -3.99 some 4.7 million years ago and outshone all other stars. Now the two stars shine at second magnitude and are easily visible even from light-polluted areas.
Equatorial latitudes
For observers near the equator, the stars of the Winter Circle appear high overhead in the evening. Sirius, Rigel, Procyon, and Betelgeuse are the brightest stars near the zenith around 10 pm. Sirius is the brightest star in the sky, and Rigel, Procyon and Betelgeuse are the seventh, eighth and 10th brightest stars, respectively.
Sirius, Procyon, and Rigel form the Winter Circle with Aldebaran, Pollux and Capella, and Betelgeuse is part of the Winter Triangle, along with Sirius and Procyon. No other region of the sky contains as many bright stars as the one appearing overhead in the evening at this time of the year.
Canopus, the second brightest star in the sky, appears high above the southern horizon, Achernar, the ninth brightest star, sits low in the southwest, and Regulus, the 21st brightest star, is the brightest point of light above the eastern horizon in the evening.
Stars visible tonight in equatorial latitudes, image: Stellarium
Northern sky
Capella is the brightest star above the northern horizon. It is the brightest star in the constellation Auriga (the Charioteer) and the sixth brightest star in the sky. The giant star is part of a quadruple star system located 42.919 light-years away.
Capella and other bright stars in Auriga form the hexagon of Auriga with Elnath, the second brightest star in Taurus. Elnath marks the northern horn of the Bull and is the top star of Auriga’s hexagon in the evening, while Capella and the fainter Menkalinan appear closer to the horizon.
The supergiant Mirfak and the eclipsing binary system Algol appear northwest of Auriga’s hexagon. They are the brightest stars in the constellation Perseus.
Mirfak is the brightest star in the Alpha Persei Cluster, an open cluster visible to the unaided eye. The supergiant is part of the Segment of Perseus, a curving line of stars visible between Cassiopeia’s W and Auriga’s hexagon.
The brightest stars of Cassiopeia (the Queen) and Ursa Major (the Great Bear) are partly visible in the northwestern and northeastern sky. Schedar, the luminary of Cassiopeia, appears low in the northwest, while Dubhe and Merak, the outer stars of the Big Dipper’s bowl lie low above the northeastern horizon.
Stars in the northern sky tonight in equatorial latitudes, image: Stellarium
Eastern sky
The brightest star visible in the eastern sky is Regulus, the lucida of the zodiac constellation Leo. Shining at magnitude 1.40, Regulus is the 21st brightest star in the sky.
The hot blue subgiant is part of the Sickle of Leo, an asterism that looks like a backward question mark and represents the celestial Lion’s head and mane. Regulus itself marks the Lion’s heart. The orange giant Algieba is part of the Sickle, while Denebola marks the Lion’s tail and appears very low above the eastern horizon.
Alphard, the luminary of Hydra (the Water Snake), is the brightest star southwest of Regulus. The evolved K-type star is the only second magnitude star in Hydra, the largest constellation in the sky.
Stars in the eastern sky tonight in equatorial latitudes, image: Stellarium
Western sky
The stars of the faint constellations Cetus (the Sea Monster) and Pisces (the Fishes) occupy much of the western sky. Diphda, the brightest star in Cetus, appears low in the sky and sets just after 10 pm. The fainter Menkar is part of a circle of stars that outline the Sea Monster’s head. It appears high above the western horizon.
Ankaa, the brightest star in Phoenix, sets in the southwestern sky, and the bright stars of Andromeda (the Princess) and Aries (the Ram) are still visible in the northwestern sky in the evening.
Mirach and Almach in Andromeda form an almost straight line with Mirfak in Perseus. They also form a conspicuous triangle with Hamal, the brightest star in Aries.
Hamal forms a flat triangle with the fainter Sheratan and Mesarthim. Hamal and Sheratan point towards Alpherg, the brightest star in the faint constellation Pisces. The relatively faint stars of the constellation Triangulum form an elongated triangle visible between the stars of Aries and Andromeda on a clear night.
Stars in the western sky tonight in equatorial latitudes, image: Stellarium
Southern sky
Canopus is the brightest star in the southern sky in the evening. The white bright giant star is the second brightest star in the sky, after Sirius. It is one of the three bright stars in Carina (the Keel) selected for use in celestial navigation. The other two, Miaplacidus and Avior, shine at second magnitude. Miaplacidus is a white A-type giant and Avior is an orange giant.
Avior and the white supergiant Aspidiske form an asterism known as the False Cross with Alsephina and Markeb in the constellation Vela (the Sails). Miaplacidus is part of the Diamond Cross, an asterism also formed by Theta, Upsilon and Omega Carinae.
The stars of Carina, Vela and Puppis (the Stern) dominate the southeastern sky. Naos, the brightest star in Puppis, is one the most luminous stars visible to the unaided eye. The hot blue supergiant has a mass 56.1 times that of the Sun and shines with a luminosity of 813,000 Suns. It shines at second magnitude from a distance of 1,080 light-years.
The Gamma Velorum system (popularly known as Regor) is the brightest point of light in Vela. It contains the nearest Wolf-Rayet star to the Sun. Suhail, the third brightest star in Vela (after Regor and Alsephina), is a variable orange supergiant located 545 light-years away. It is about 210 times larger than the Sun.
Achernar is the brightest star in the southwestern sky. The hot blue main sequence star has six times the Sun’s mass and is 3,493 times more luminous. Shining at magnitude 0.40 – 0.46, it is the ninth brightest star in the sky and the lucida of the constellation Eridanus (the River). It marks the southern end of the celestial River.
Stars in the southern sky tonight in equatorial latitudes, image: Stellarium
Southern hemisphere
For observers in the southern hemisphere, 14 of the 21 first magnitude stars appear above the horizon around 10 pm. The brightest star high overhead in the evening is Canopus, the second brightest star in the sky. The brighter Sirius, the Dog Star, appears high above the eastern horizon. Rigel, the seventh brightest star, lies high in the northeastern sky, and Achernar, the ninth brightest star, is high in the southwest.
Other first-magnitude stars visible around 10 pm are Aldebaran in the constellation Taurus (the Bull), Betelgeuse in Orion (the Hunter), Procyon in Canis Minor (the Lesser Dog), Capella in Auriga (the Charioteer), Pollux in Gemini (the Twins), Fomalhaut in Piscis Austrinus (the Southern Fish), Rigil Kentaurus and Hadar in Centaurus (the Centaur), and Acrux and Mimosa in Crux (the Southern Cross).
Stars visible tonight in the southern hemisphere, image: Stellarium
Northern sky
The brightest stars in the northern sky are Capella, Aldebaran and Rigel. Capella, the brightest star in the constellation Auriga, appears close to the horizon. It forms Auriga’s hexagon with Menkalinan, Almaaz, Mahasim, Hassaleh, and Elnath.
Elnath is the only one of these stars that does not fall within Auriga’s borders. It marks the northern horn of Taurus, the celestial Bull.
The giant Aldebaran, the brightest star in Taurus, is part of the Bull’s head and marks one of the Bull’s eyes. It lies in the same line of sight as the bright, large Hyades cluster. The V-shaped open cluster outlines the Bull’s head and can be used as a pointer to find the head of the fainter Cetus (the Sea Monster or the Whale).
Hamal, the brightest star in Aries, appears above the northwestern horizon around 10 pm. The orange giant shines at magnitude 2.0 from a distance of 65.8 light-years. It appears near the faint elongated triangle formed by the brightest stars in the northern constellation Triangulum.
The bright stars of Orion and Gemini dominate the northeastern sky. Pollux and Castor, the stars marking the heads of the celestial Twins, appear almost parallel to the horizon in the evening.
The seven brightest stars of Orion form a crooked hourglass pattern that makes the Hunter one of the most recognizable constellations in the sky. Betelgeuse, the constellation’s second brightest star, is the only red star in the group. The supergiant shines at magnitude 0.50 from a distance of 550 light-years and is, on average, the 10th brightest star in the sky.
Stars in the northern sky tonight in the southern hemisphere, image: Stellarium
Like almost all bright stars in Orion, Betelgeuse is a supernova candidate. Even though it is only about 8 million years old, it will live a very short life due to its high mass. The red star is already in the final stages of its life cycle.
The brighter Rigel is much more distant and intrinsically luminous. The hot blue supergiant lies 848 light-years away. With an apparent magnitude of 0.05 – 0.18, it is the seventh brightest star in the sky. With 21 times the Sun’s mass, it is another certain supernova candidate.
With the exception of Bellatrix, other bright stars of Orion will also meet their ends as fiery supernovae. Bellatrix may join them, or it may instead end its life as a massive white dwarf.
The supergiants Alnitak, Alnilam and Saiph and the giant Mintaka are all hot blue stars tens or hundreds of thousands times more luminous than the Sun. Alnitak, Alnilam and Mintaka form Orion’s Belt, one of the most familiar asterisms in the night sky.
Eastern sky
Alphard is the brightest star appearing directly east. The brightest star in Hydra appears high above the eastern horizon in an area devoid of bright stars. It is a K-type bright giant or giant star with 3 times the Sun’s mass and a radius of 50.5 solar radii. It lies approximately 177 light-years away.
Sirius and Procyon, the brightest stars in the dog constellations Canis Major and Canis Minor, appear higher in the eastern and northeastern sky.
Sirius, the brightest star in Earth’s sky, is the only bright star in the Great Dog constellation that will not go out as a supernova when it reaches the end of its life cycle. Its fainter neighbours Mirzam, Wezen, Adhara and Aludra are all massive, luminous stars that lie at greater distances and will have spectacular ends. Adhara, Mirzam and Aludra are hot, evolved B-type stars and Wezen is an F-type supergiant.
Sirius lies only 8.60 light-years away and is the seventh closest individual star to the solar system. It has a white dwarf companion, nicknamed the Pup, that is the nearest white dwarf to the Sun.
Sirius and Procyon are the third and fifth nearest stars visible to the unaided eye. Sirius is still on the main sequence and Procyon is coming to the end of its main sequence life cycle. The luminary of Canis Minor lies 11.46 light-years away. It is the eighth brightest star in the sky. Like Sirius, it has a white dwarf companion.
Stars in the eastern sky tonight in the southern hemisphere, image: Stellarium
The stars of Carina (the Keel), Vela (the Sails) and Puppis (the Stern) appear high in the eastern and southeastern sky.
Miaplacidus and Avior, the second and third brightest stars in Carina (after Canopus), form two diamond-shaped asterisms that are sometimes mistaken for the Southern Cross. Miaplacidus forms the Diamond Cross with Theta, Upsilon and Omega Carinae, while Avior is part of the False Cross, along with Aspidiske in Carina and Alsephina and Markeb in Vela.
Carina’s four brightest stars – Canopus, Miaplacidus, Avior and Aspidiske – are all evolved, massive stars located over a hundred light-years away. Canopus is an A-type bright giant with 8 times the Sun’s mass and 10,700 times its luminosity. It lies 310 light-years away. Miaplacidus is a white A-type giant 113.2 light-years away and Avior is an orange giant 610 light-years away. Aspidiske, the most distant of these stars, is a white supergiant of spectral type A9 Ib located 690 light-years away.
Naos, the brightest star in the neighbouring Puppis, is one of the nearest O-type stars to the Sun. Located 1,080 light-years away, the star has 56.1 times the Sun’s mass and 813,000 times its luminosity.
Naos in Puppis and Alsephina in Vela both have names that are derived from the Greek and Arabic words for “ship.” The names refer to Argo Navis (the Ship Argo), an obsolete constellation that represented the mythical ship on which Jason and the Argonauts sailed to Colchis to retrieve the Golden Fleece. Argo Navis consisted of what are now the constellations Carina (the Keel), Puppis (the Stern), and Vela (the Sails).
Alsephina is the only one of the four brightest stars in Vela that is still on the main sequence. It is an A-type star in an Algol-type eclipsing binary system. It lies 80.6 light-years away.
Regor, the brightest star in Vela, is part of a star system that contains two supernova candidates, the nearest Wolf-Rayet star to the Sun and a massive O-type supergiant. The system lies approximately 1,236 light-years away.
Suhail is a K-type supergiant located 545 light-years away and Markeb, one of the stars of the False Cross, is a hot blue giant located 570 light-years away.
Western sky
Fomalhaut and Diphda, the luminaries of the constellations Piscis Austrinus (the Southern Fish) and Cetus (the Sea Monster), are the brightest stars above the western horizon in the evening. They are the 18th and 51st brightest stars in the sky.
Fomalhaut marks the mouth of the Southern Fish, into which the celestial Water Bearer (Aquarius) is pouring water, and Diphda appears in the tail of the Sea Monster associated with the myth of Andromeda. Fomalhaut is a main sequence star in the solar neighbourhood, located about 25 light-years away, and Diphda is an orange giant 96.3 light-years away.
Achernar, the ninth brightest star in the sky, appears high in the southwestern sky. Its name comes from an Arabic phrase meaning “the end of the River” and refers to the star’s position at the southernmost end of the constellation Eridanus (the River). Achernar is a fast-spinning hot blue main sequence star with a mass 6 times that of the Sun and a luminosity of 3,493 Suns.
Stars in the western sky tonight in the southern hemisphere, image: Stellarium
Southern sky
Four first-magnitude stars appear low in the southern evening sky. Rigil Kentaurus and Hadar, the brightest stars in the constellation Centaurus, are the third and 11th brightest stars in the sky. The two stars point in the direction of the giant star Gacrux at the top of the Southern Cross.
Rigil Kentaurus is the brightest component of Alpha Centauri, the nearest star system to the Sun. Its close neighbour Toliman also shines at first magnitude, while the red dwarf Proxima Centauri, the nearest individual star to the solar system, is invisible to the unaided eye. The system lies 4.344 light-years away.
Like Proxima, Rigil Kentaurus and Toliman are still on the main sequence. Rigil Kentaurus is a Sun-like G-type star slightly larger and more massive than the Sun, while Toliman is an orange dwarf slightly smaller and less luminous than the Sun.
In contrast, Hadar is a hot, luminous B-type giant located 390 light-years away. It forms a triple star system with another blue giant and a blue main sequence star. The two brighter components of the Beta Centauri system are both supernova candidates with masses of more than 10 times that of the Sun.
The second-magnitude Epsilon and Gamma Centauri are also visible above the southern and southeastern horizon. Gamma Centauri appears along the imaginary line extended through the Southern Cross, while Epsilon lies closer to Alpha and Beta Centauri.
Epsilon is a hot blue giant about 430 light-years away, and Gamma is a blue-white subgiant 130 light-years away. Epsilon Centauri will end its life as a supernova, and Gamma Centauri will meet its end as a white dwarf.
Stars in the southern sky tonight in the southern hemisphere, image: Stellarium
The triangle that gives the constellation Triangulum Australe (the Southern Triangle) its name appears directly south in the evening. It is formed by the orange giant (or bright giant) Atria with the fainter main sequence stars Beta and Gamma Trianguli Australis.
Acrux and Mimosa, the brightest stars of the constellation Crux, are the 13th and 20th brightest stars in the sky. They form the Southern Cross, the most familiar asterism in the southern hemisphere, with the fainter Gacrux, Imai and Ginan.
Like Hadar and Epsilon Centauri, Acrux and Mimosa are hot, evolved B-type stars that will meet their ends as fiery supernovae. These stars are members of the same family, the Scorpius-Centaurus association. They formed together in the same molecular cloud and are now moving together through space.
Acrux is part of a multiple star system whose brightest components have masses 17.80 and 15.52 times that of the Sun and are both supernova candidates. The Alpha Crucis system lies 320 light-years away.
Mimosa (or Becrux) has 16 times the Sun’s mass and is 34,000 times more luminous. It forms a star system with another hot blue star with 10 times the Sun’s mass and a pre-main sequence star. The components of Beta Crucis lie approximately 280 light-years away.
Gacrux, a red giant located 88.6 light-years away, is not a member of the same family. Shining at magnitude 1.64, it is the third brightest star in Crux and the 25th brightest star in the sky. With a mass of 1.5 solar masses, it will have a much longer life than its brighter neighbours.
The stars of the Southern Birds constellations Phoenix, Pavo (the Peacock), Grus (the Crane) and Tucana (the Toucan) occupy much of the southwestern sky.
The orange giant Ankaa, the luminary of Phoenix, appears high in the sky, near the bright Canopus. Alnair and Tiaki, the brightest stars in Grus, appear perpendicular to the horizon, while Peacock in Pavo lies lower in the sky in the evening. The third-magnitude orange giant Alpha Tucanae appears east of Alnair and north of Peacock.
Alnair and Peacock are both hot, blue B-type main sequence stars, while Tiaki is a red giant. All three stars are larger, more massive and more luminous than the Sun. Alnair lies 101 light-years away, and Tiaki and Peacock lie 177 and 179 light-years away.