Vela – The Sails

Genitive: Velorum
Abbreviation: Vel
Size ranking: 32nd
Origin:Part of the original Greek constellation Argo Navis
 
One of the three sections into which the French astronomer Nicolas Louis de Lacaille divided the oversized Greek constellation of Argo Navis, the Argonauts’ ship, in his southern star catalogue of 1756. In that preliminary catalogue he gave it the French name Voilure du Navire, which was Latinized to Vela in his final catalogue, Coelum australe stelliferum of 1763.
 
Vela represents the ship’s sails; the other sections are Carina, the Keel, and Puppis, the Stern. Lacaille wrote: ‘I have called the sails [i.e. Vela] everything outside the vessel between the edges and the horizontal mast, or the spar on which the sail is reefed’.
vela

Traditionally the sail of Argo has been shown furled around a cross-spar on the main mast, as in the Uranometria of Johann Bayer (1603), and not open and billowing as imagined in some popular representations.
© Tartu Observatory Virtual Museum.
 
 
Not only did Lacaille dismantle Argo Navis, he also relabelled its stars, since he was dissatisfied with Bayer’s earlier arrangement. But he still used only one set of Greek letters for all three parts of Argo. As a result, Vela possesses no stars labelled Alpha or Beta, since these letters were allocated to the two brightest stars in Carina. For fainter stars in each constellation Lacaille turned to Roman letters, both lowercase and uppercase.
 
Vela’s brightest star is Gamma Velorum, a second-magnitude double star. Delta and Kappa Velorum, along with Epsilon and Iota Carinae in adjoining Carina, form a cruciform shape known as the False Cross; this is sometimes mistaken for the true Southern Cross, although it is larger and fainter than the real thing.

Chinese associations
Five stars in Vela formed the Chinese constellation Ji, representing a temple to Hou Ji, the god of cereals. Ji itself refers to millet, which was the main crop in ancient China. However, the exact stars involved are uncertain.
 
Even greater uncertainty surrounds other Chinese constellations in this far southern area of sky. One such is Tianshe, ‘celestial altar’. In Chinese fable, Tianshe represented an altar used to make offerings to the Earth god Julong. One version identifies its six stars as Gamma, b, Omicron, Delta, Kappa, and N Velorum. Sun and Kistemaker, though, depict it zig-zagging from Chi Carinae via Gamma Velorum and on into Puppis, while a third interpretation confines it to Puppis alone. Another problematic constellation is Qifu, a storehouse for musical instruments, consisting of 32 stars mostly in Centaurus but perhaps spilling over into Vela as well.
 
Two or three stars in northern Vela, including q and i, formed part of Dong’ou, which straddled the border with Antlia. This constellation was named after a place on the Chinese coast where barbarians were said to live.
 
One individual star in this region was known as Tianji, representing an assessor who decided whether animals were old enough to be sacrificed. This star has been identified either as Lambda Velorum or 12 Hydrae; the latter identification may be more probable as it would place it closer to the kitchen, Waichu, in Hydra where the animals were actually slaughtered.
 
 
© Ian Ridpath. All rights reserved
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Ursa Minor – The Little Bear

Genitive: Ursae Minoris
Abbreviation: UMi
Size ranking: 56th
Origin: One of the 48 Greek constellations listed by Ptolemy in the Almagest
Greek name:Ἄρκτος Μικρά (Arktos Mikra)
 
The Little Bear was said by the Greeks to have been first named by the astronomer Thales of Miletus, who lived from about 625 to 545 BC. The earliest reference to it seems to have been made by the poet Callimachus of the third century BC, who reported that Thales ‘measured out the little stars of the Wain [wagon] by which the Phoenicians sail’. The little bear was evidently unknown to Homer, two centuries before Thales, for he wrote only of the Great Bear, never mentioning its smaller counterpart.
 
It is not clear whether Thales actually invented the constellation or merely introduced it to the Greeks, for Thales was reputedly descended from a Phoenician family and, as Callimachus said, the Phoenicians navigated by reference to Ursa Minor rather than Ursa Major. Aratus points out that although the Little Bear is smaller and fainter than the Great Bear, it lies closer to the pole and hence provides a better guide to true north. We have the word of Eratosthenes that the Greeks also knew Ursa Minor as Φοινίκη (Phoenike), i.e. the Phoenician. In the sky the two bears stand back to back, facing in opposite directions, with the tail of Draco the dragon between them.
umin

Ursa Minor from the Atlas Coelestis of John Flamsteed (1729).
Polaris, the north pole star, lies at the tip of its unnaturally long tail.

 
Aratus called the constellation Κυνόσουρα (i.e. Kynosoura, or Cynosura in Latin transliteration), Greek for ‘dog’s tail’. This is the origin of the English word cynosure, meaning ‘guiding star’. Cynosura was still in use as an alternative name for Ursa Minor in Tycho Brahe’s star catalogue published in 1602.
 
According to Aratus the Little Bear represents one of the two nymphs who nursed the infant Zeus in the cave of Dicte on Crete. Apollodorus tells us that the nurses’ names were Adrasteia and Ida. Ursa Minor commemorates Ida while Adrasteia, the senior of the two, is Ursa Major.
 
In the Almagest it appears under the Greek name Ἄρκτος Μικρά (Arktos Mikra). Ptolemy catalogued seven stars as part of the Little Bear, four in the body and three in the tail; an eighth star (the modern-day 5 UMi) was also listed but was regarded as lying outside the constellation. These seven stars have a similar ladle shape to the Big Dipper of Ursa Major, and so are popularly termed the Little Dipper. At the end of the Little Bear’s tail (or the dipper’s handle) is the star Alpha Ursae Minoris, commonly known by the Latin name Polaris because it is currently the nearest bright star to the north celestial pole, although that has not always been the case. 
 
Polaris and the north celestial pole
In Ptolemy’s day (2nd century AD) there was no bright star near the north celestial pole. The star we know as Polaris was then some 11° away. Kochab (Beta Ursae Minoris) was closer, but only by a couple of degrees. Over the ensuing centuries, though, the effect of precession slowly moved the celestial pole towards Alpha Ursae Minoris.
 
According to the German star-name expert Paul Kunitzsch (private communication), the first known usage of the name ‘stella polaris’ applied to this star in print was in an edition of the Alfonsine Tables published in Venice in 1492. (The Alfonsine Tables were an updated version of Ptolemy’s Almagest prepared in Toledo, Spain, around 1260 on the order of King Alfonso the Wise. The first printed edition of the Tables was in 1483; earlier copies were in manuscript form only.) The name Stella Polaris also occurs on a globe of 1493 by Johannes Stöffler (1452–1531) and in books by Stöffler and Peter Apian (1495–1552) in the early 16th century. At that time, Polaris was still around three and a half degrees from the celestial pole, five times farther than it is at present, but was clearly becoming accepted as the pole star. Prior to that, the closest star of any note to the pole was 5th-magnitude Struve 1694 (aka HR 4893) in Camelopardalis.
 
Contrary to common belief, Polaris is not particularly bright. It is in fact of magnitude 2.0, just on the fringe of the top 50 brightest stars as seen by the naked eye. Currently it lies within a degree of the exact north celestial pole, close enough to make it an excellent guide star for navigators. Polaris will reach its closest to the north celestial pole around AD 2100, when the separation will be less than half a degree. After that, precession will just as inexorably move the celestial pole away from it again.
 
Other stars of Ursa Minor
The second star in the Little Bear’s tail, Delta Ursae Minoris, is called Yildun, a mis-spelling of the Turkish word yildiz meaning ‘star’. According to Paul Kunitzsch this was wrongly thought to be a Turkish name for the pole star in Renaissance times, and it has since been arbitrarily applied to the star nearest to the true pole star.
 
The 10th-century Arabic astronomer al-Sūfī noted in his Book of the Fixed Stars that an Arab tradition saw the arc of stars forming the handle of the Little Dipper as representing one side of the body of a fish, al-fa’s. The other side consisted of much fainter stars, including the present-day 4 and 5 Ursae Minoris and Struve 1694 (HR 4893) in Camelopardalis; as noted above, this latter star was the pole star of its time.
 
Two stars in the bowl of the Little Dipper, Beta and Gamma Ursae Minoris, are sometimes referred to as the Guards or Guardians of the Pole. Their names are Kochab and Pherkad, and they were seen by the Arabs as a pair of calves. Paul Kunitzsch has been unable to trace the origin of Kochab, but thinks that it may come from the Arabic word kaukabmeaning ‘star’. Pherkad is from al-farkadan, meaning ‘the two calves’.

Chinese associations
In ancient China, the polar region of the sky took on immense symbolism because of its literally pivotal position, mirroring the central authority of the Emperor on Earth. The area including the modern Ursa Minor plus parts of Camelopardalis, Draco, Cepheus, and Cassiopeia was known to the Chinese as Ziwei, the Purple Palace Enclosure or Central Palace. Surrounding it was a wall delineated by 15 stars, divided into western and eastern sections. The eastern wall started in present-day Draco and went through Cepheus into Cassiopeia, while the western section was in Draco, Ursa Major, and Camelopardalis.
 
Within this central enclosure lived the Emperor and his immediate family, depicted as an arc of five stars called Beiji, the North Pole Office. In sequence polewards they were: Taizi, the Crown Prince (Gamma Ursae Minoris); Di, the Emperor himself (Beta UMi), described as ‘the reddest and brightest star of the group’; Shuzi, son of a concubine (5 UMi); and Hougong, the Imperial Concubine or Empress (4 UMi). At the end of the chain, over the border in Camelopardalis, was Struve 1694; this was known as Tianshu, the Celestial Pivot, or Niuxing, Pivot Star, because it was closest to the celestial pole and hence acted as the pole star in those times despite being a mere 5th magnitude. Keeping with the domestic theme, six faint stars in southern Ursa Minor and Draco formed the Emperor’s bedroom, Tianchuang.
 
Although Chinese astronomers did not recognize the Little Dipper we know today, they did have a similar dipper shape called Gouchen (‘curved array’) formed by some of the same stars: Zeta, Epsilon, Delta, and Alpha Ursae Minoris, plus two other unlabelled stars in Cepheus. What Gouchen represents is unclear, though – it is variously described as the Empress, the residence of the Emperor, or even six generals.
 
Gouchen contains the present-day Polaris, but it was not known as that in ancient Chinese times. It is usually said that the Chinese called this star Tianhuang dadi, meaning ‘great emperor of heaven’ or ‘high god of heaven’, referring to the ultimate sky god – presumably the authority from which the terrestrial Emperor took his mandate to rule on Earth. However, Sun Xiaochun and Jacob Kistemaker suggest in their book The Chinese Sky During the Han that this name actually applied not directly to Polaris but to a much fainter star or even a blank area of sky near to it, since the ultimate deity should be mysterious and invisible.
 
 
© Ian Ridpath. All rights reserved

Ursa Major – The Greater Bear

Genitive: Ursae Majoris
Abbreviation: UMa
Size ranking: 3rd
Origin: One of the 48 Greek constellations listed by Ptolemy in the Almagest
Greek name:Ἄρκτος Μεγάλη (Arktos Megale)
 
Undoubtedly the most familiar star pattern in the entire sky is the seven stars that make up the shape popularly termed the Plough or Big Dipper, part of the third-largest constellation, Ursa Major, the Great Bear. The seven stars form the rump and tail of the bear, while the rest of the animal is comprised of fainter stars. Its Greek name in the Almagest was Ἄρκτος Μεγάλη (Arktos Megale); Ursa Major is the Latin equivalent.
 
Aratus called the constellation Ἑλίκη (Helike), meaning ‘twister’, apparently from its circling of the pole, and said that the ancient Greeks steered their ships by reference to it. In the Odyssey, for example, we read that Odysseus kept the great bear to his left as he sailed eastwards. The Phoenicians, on the other hand, used the Little Bear (Ursa Minor), which Aratus termed Κυνόσουρα (Kynosoura, or Cynosura in Latin transliteration). Aratus tells us that the bears were also called wagons or wains, and in one place he referred to the figure of Ursa Major as the ‘wagon-bear’ to underline its dual identity.
 
Homer in the Odyssey referred to ‘the Great Bear that men call the Wain, that circles opposite Orion, and never bathes in the sea’, the last phrase being a reference to its circumpolar (non-setting) nature. The adjacent constellation Boötes was imagined as either the herdsman of the bear or the wagon driver. Germanicus Caesar seems to have been the first to mention a third, now-common identity – he said that the bears were also called ploughs because, as he wrote, ‘the shape of a plough is the closest to the real shape formed by their stars’.
Ursamajor2.jpg

Ursa Major as depicted on Chart VI of the Uranographia of Johann Bode (1801).
The familiar shape popularly known as the Plough or Big Dipper is made up of
seven stars in the rump and tail of the bear.

 
 
According to Hyginus the Romans referred to the Great Bear as Septentrio, meaning ‘seven plough oxen’, although he added the information that in ancient times only two of the stars were considered oxen, the other five forming a wagon. On a star map of 1524 the German astronomer Peter Apian (1495–1552) showed Ursa Major as a team of three horses pulling a four-wheeled cart, which he called Plaustrum, harking back to the Roman tradition. The word septentrional was commonly used in Latin as a synonym for ‘north’.
 
In mythology, the Great Bear is identified with two separate characters: Callisto, a paramour of Zeus; and Adrasteia, one of the ash-tree nymphs who nursed the infant Zeus. To complicate matters, there are several different versions of each story, particularly the one involving Callisto.
 
The story of Callisto
Callisto is usually said to have been the daughter of Lycaon, king of Arcadia in the central Peloponnese. (An alternative story says that she is not Lycaon’s daughter but the daughter of Lycaon’s son Ceteus. In this version, Ceteus is identified with the constellation Hercules, kneeling and holding up his hands in supplication to the gods at his daughter’s transformation into a bear.)
 
Callisto joined the retinue of Artemis, goddess of hunting. She dressed in the same way as Artemis, tying her hair with a white ribbon and pinning together her tunic with a brooch, and she soon became the favourite hunting partner of Artemis, to whom she swore a vow of chastity. One afternoon, as Callisto laid down her bow and rested in a shady forest grove, Zeus caught sight of her and was entranced. What happened next is described fully by Ovid in Book II of his Metamorphoses. Cunningly assuming the appearance of Artemis, Zeus entered the grove to be greeted warmly by the unsuspecting Callisto. He lay beside her and embraced her. Before the startled girl could react, Zeus revealed his true self and, despite Callisto’s struggles, had his way with her. Zeus returned to Olympus, leaving the shame-filled Callisto scarcely able to face Artemis and the other nymphs.
 
On a hot afternoon some months later, the hunting party came to a cool river and decided to bathe. Artemis stripped off and led them in, but Callisto hung back. As she reluctantly undressed, her advancing pregnancy was finally revealed. She had broken her vow of chastity! Artemis, scandalized, banished Callisto from her sight.
 
Callisto becomes a bear
Worse was to come when Callisto gave birth to a son, Arcas. Hera, the wife of Zeus, had not been slow to realize her husband’s infidelity and was now determined to take revenge on her rival. Hurling insults, Hera grabbed Callisto by her hair and pulled her to the ground. As Callisto lay spreadeagled, dark hairs began to sprout from her arms and legs, her hands and feet turned into claws and her beautiful mouth which Zeus had kissed turned into gaping jaws that uttered growls.
 
For 15 years Callisto roamed the woods in the shape of a bear, but still with a human mind. Once a huntress herself, she was now pursued by hunters. One day she came face to face with her son Arcas. Callisto recognized Arcas and tried to approach him, but he backed off in fear. He would have speared the bear, not knowing it was really his mother, had not Zeus intervened by sending a whirlwind that carried them up into heaven, where Zeus transformed Callisto into the constellation Ursa Major and Arcas into Boötes.
 
Hera was now even more enraged to find her rival glorified among the stars, so she consulted her foster parents Tethys and Oceanus, gods of the sea, and persuaded them never to let the bear bathe in the northern waters. Hence, as seen from mid-northern latitudes, the bear never sets below the horizon.
 
That this is the most familiar version of the myth is due to Ovid’s pre-eminence as a storyteller, but there are other versions, some older than Ovid. Eratosthenes, for instance, says that Callisto was changed into a bear not by Hera but by Artemis as a punishment for breaking her vow of chastity. Later, Callisto the bear and her son Arcas were captured in the woods by shepherds who took them as a gift to King Lycaon. Callisto and Arcas sought refuge in the temple of Zeus, unaware that Arcadian law laid down the death penalty for trespassers. (Yet another variant says that Arcas chased the bear into the temple while hunting – see Boötes.) To save them, Zeus snatched them up and placed them in the sky.
 
The Greek mythographer Apollodorus says that Callisto was turned into a bear by Zeus to disguise her from his wife Hera. But Hera saw through the ruse and pointed out the bear to Artemis who shot her down, thinking that she was a wild animal. Zeus sorrowfully placed the image of the bear in the sky.
 
Other identifications
Aratus makes a completely different identification of Ursa Major. He says that the bear represents one of the nymphs who raised Zeus in the cave of Dicte on Crete. That cave, incidentally, is a real place where local people still proudly point out the supposed place of Zeus’s birth. Rhea, his mother, had smuggled Zeus to Crete to escape Cronus, his father. Cronus had swallowed all his previous children at birth for fear that one day they would overthrow him – as Zeus eventually did. Apollodorus names the nurses of Zeus as Adrasteia and Ida, although other sources give different names. Ida is represented by the neighbouring constellation of Ursa Minor, the Little Bear.
 
These nymphs looked after Zeus for a year, while armed Cretan warriors called the Curetes guarded the cave, clashing their spears against their shields to drown the baby’s cries from the ears of Cronus. Adrasteia laid the infant Zeus in a cradle of gold and made for him a golden ball that left a fiery trail like a meteor when thrown into the air. Zeus drank the milk of the she-goat Amaltheia with his foster-brother Pan. Zeus later placed Amaltheia in the sky as the star Capella, while Adrasteia became the Great Bear – although why Zeus turned her into a bear is not explained.
 
Why a bear?
An enduring puzzle concerning Ursa Major and its companion Ursa Minor is why they came to be regarded as bears when they do not look at all bear-like. Both of the celestial bears have long tails, which real bears do not, an anatomical oddity which the mythologists never explained. Thomas Hood, an English astronomical writer of the late 16th century, offered the tongue-in-cheek suggestion that the tails had become stretched when Zeus pulled the bears up into heaven. ‘Other reason know I none’, he added apologetically.
 
Peter Blomberg, a Swedish historian of astronomy, has proposed that the identification of these constellations as bears is due to a linguistic ambiguity. The early Greeks referred to the northern area of the sky as αρκτος (i.e. arktos), a word which can mean northern (as in Arctic) as well as bear. Blomberg believes that the word was originally used in the former sense, i.e. that the constellations were in the north, and that its alternative meaning, that of a bear, was adopted later. Is it possible, in that case, that two of our most familiar and best-loved constellations owe their identities to a simple misinterpretation?
Stars of Ursa Major
Two stars in the bowl of the Dipper, Dubhe and Merak (Alpha and Beta Ursae Majoris), are popularly termed the Pointers because a line drawn through them points to the north celestial pole. Dubhe’s name comes from the Arabic al-dubb, ‘the bear’, while Merak comes from the Arabic word al-maraqq meaning ‘the flank’ or ‘groin’. At the tip of the bear’s tail lies Eta Ursae Majoris, known as Alkaid, from the Arabic al-qa’id meaning ‘the leader’; an alternative name was Benetnasch, from the Arabic banat na’sh meaning ‘daughters of the bier’, for the Arabs regarded this figure not as a bear but as a bier or coffin. They saw the tail of the bear as a line of mourners (the ‘daughters’) leading the coffin.
 
Second in line along the tail is the wide double star Zeta Ursae Majoris. The two members of the double, visible separately with keen eyesight, are called Mizar and Alcor. They were depicted as a horse and its rider on the 1524 star chart of Peter Apian, apparently following a popular German tradition. The name Mizar is a corruption of the Arabic al-maraqq, the same origin as the name Merak. Its companion, Alcor, gets its name from a corruption of the Arabic al-jaun, meaning ‘the black horse or bull’. This is the same origin as the name Alioth which is applied to the next star along the tail, Epsilon Ursae Majoris.
 
The name the Arabs used for Alcor was al-suha, meaning the overlooked or neglected one. (Ptolemy certainly overlooked it, as he did not include it in the Almagest.) The 10th-century Arabic astronomer al-Sūfī noted that this star was used by people to test their eyesight. He quoted an Arabic saying: ‘I showed him al-suha and he showed me the Moon’, as a comparison between people with good and bad eyesight. Ophthalmologist George M. Bohigian has concluded that the ability to divide Mizar and Alcor is comparable to the standard Snellen test for 20/20 vision.
 
Delta Ursae Majoris is named Megrez, from the Arabic word maghriz meaning ‘root of the tail’. Gamma Ursae Majoris is called Phecda, from the Arabic word fakhidh meaning ‘the thigh’.
 
In addition to the famous seven stars of the Plough or Dipper there are three pairs of stars that mark the feet of the bear. The Arabs imagined these as forming the hoof prints of a leaping gazelle; according to an Arabic folk tale, the gazelle jumped when it heard the lion hit its tail on the ground. The pair Nu and Xi Ursae Majoris (marking the bear’s right hind paw according to Ptolemy) are called Alula Borealis and Alula Australis. The word Alula comes from an Arabic phrase meaning ‘first leap’; the distinctions ‘northern’ (Borealis) and ‘southern’ (Australis) are added in Latin. The second leap is represented by Lambda and Mu Ursae Majoris, known as Tania Borealis and Tania Australis; these stars were described by Ptolemy as being in the bear’s left hind paw. The third leap (and the bear’s front left paw) is represented by Iota and Kappa Ursae Majoris; Iota has the name Talitha, from the Arabic meaning ‘third’, but Kappa is unnamed.
 
Ptolemy listed 27 stars as members of the constellation, plus another eight that he regarded as lying outside it (i.e. they were unformed). Two of these unformed stars were later incorporated by Johannes Hevelius into Canes Venatici, where they are now known as Alpha and Beta CVn. The others became part of another Hevelius invention, Lynx.
 

Chinese associations
Chinese astronomers knew the shape of the Plough as Beidou, the Northern Dipper (they had a Southern Dipper as well, in Sagittarius). It was also seen as the chariot of the Emperor, controlling the sky as it revolves around the pole. Beidou is one of the few Chinese constellations that is readily recognizable to western eyes. Each of the seven stars had its own name: Alpha (Dubhe) was Tianshu, ‘celestial pivot’ (not to be confused with the Tianshu in Camelopardalis which was the pole star of its time); Beta (Merak) was Tianxuan, ‘celestial rotating jade’; Gamma (Phecda) was Tianji, ‘celestial shining pearl’; Delta (Megrez) was Tianquan, ‘celestial balance’; Epsilon (Alioth) was Yuheng, ‘jade sighting-tube’; Zeta (Mizar) was Kaiyang, ‘opener of heat’ (i.e. a regulator of the seasons); and Eta (Alkaid) was Yaoguang, ‘twinkling brilliance’ (also translated as ‘glittering light’). An eighth star, Fu, was regarded as the Emperor’s assistant or the prime minister; authorities differ as to whether this is Alcor, the companion to Mizar, or another faint star nearby.
 
A ring of six faint stars near Merak including 36 and 44 UMa was known as Tianlao, a prison for noblemen (the prison for commoners was in Corona Borealis), although some maps place this group south of Psi UMa. Tianli, the judge responsible for imprisoning the noblemen, was represented by four faint stars including 66 UMa within the bowl of the Dipper.
 
Six stars in the forelegs and head of the bear formed an arc called Wenchang, the administrative centre, representing six officers or departments of the celestial government. Sources differ as to exactly which six stars were involved, but Upsilon, Phi, Theta, and 15 UMa were among them.
 
There are various other faint Chinese constellations in this area which are difficult to identify with any certainty. To the north of Wenchang was Sanshi (formerly known as Sangong), a trio of stars representing three tutors. Neijie, ‘inner steps’, was a group of six stars representing steps between Wenchang and the polar region of the sky. The Chinese referred to the area around the celestial pole as the Purple Palace or Central Palace. The star 24 Ursae Majoris formed part of one of the walls enclosing this circumpolar region; the complete wall extended from Draco to Camelopardalis (for more on the Central Palace, see Ursa Minor).
 
South of the bowl of the Dipper were two named single stars. One was called Taiyangshou, ‘guard of the Sun’, usually identified as Chi Ursae Majoris, while Psi Ursae Majoris was Taizun, representing royal relatives or ancestors. In southern Ursa Major, the three pairs of stars that the Arabs visualized as the tracks of a leaping gazelle were known in China as Santai, ‘three steps’, either leading to the administrative centre Wenchang, or steps that allowed the Emperor to travel between Earth and sky – literally, three steps to Heaven.
 
 
© Ian Ridpath. All rights reserved

Tucana – The Toucan

Genitive: Tucanae
Abbreviation: Tuc
Size ranking: 48th
Origin: The 12 southern constellations of Keyser and de Houtman
 
One of the 12 southern constellations devised by the Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman at the end of the 16th century. It represents the South American bird with a huge bill.
 
The Dutchman Petrus Plancius gave it the name Toucan when he first depicted it on a globe in 1598, and Johann Bayer followed suit on his atlas of 1603. But de Houtman, in his catalogue of 1603, called it Den Indiaenschen Exster, op Indies Lang ghenaemt (‘the Indian magpie, named Lang in the Indies’, the word ‘lang’ referring to the bird’s long beak). De Houtman was apparently describing not a toucan but the hornbill, a similarly endowed bird that is native to the East Indies and Malaysia. This suggests that the original inventor of Tucana was in fact Keyser, who had visited South America before his voyage to the East Indies and could have seen the bird there. In some depictions which used de Houtman’s catalogue as a source, such as Willem Janszoon Blaeu’s globe of 1603, the bird was shown as a hornbill rather than a toucan, complete with casque above its bill, but the original identification as a toucan won out.
 
Tucana’s brightest star, Alpha Tucanae, marking the tip of the bird’s beak, is of only third magnitude, but the constellation is distinguished by two features of particular interest: firstly, the globular star cluster 47 Tucanae, rated the second-best such object in the entire sky, so bright that it was labelled in the same way as a star; and the Small Magellanic Cloud, the smaller and fainter of the two companion galaxies of our Milky Way. These features were originally part of Hydrus but were transferred to Tucana when the French astronomer Nicolas Louis de Lacaille reorganized this part of the southern heavens in the 1750s.

Incidentally, 47 Tucanae is not a Flamsteed number; it comes from its listing in Johann Bode’s catalogue called Allgemeine Beschreibung und Nachweisung der Gestirne, published in 1801 to accompany his Uranographia star atlas. It was first recorded as a star by Keyser and de Houtman. Bayer showed it on his southern star chart of 1603 within one of the coils of Hydrus, beneath the claw of the toucan, but its nebulous nature was first noted by Lacaille a century and a half later.
 
None of the stars of Tucana is named, and there are no legends associated with it.
tucana.JPG

Tucana, holding in its beak a branch with a berry, as seen on Chart XX of the Uranographia star atlas of Johann Bode (1801). Behind its tail lies Nubecula Minor, the Small Magellanic Cloud (just visible at the lower right edge of the image), which is within the constellation’s modern borders.
 
 
© Ian Ridpath. All rights reserved

Triangulum Australe – The Southern Triangle

Genitive: Trianguli Australis
Abbreviation: TrA
Size ranking: 83rd
Origin: The 12 southern constellations of Keyser and de Houtman
 
One of the 12 constellations introduced at the end of the 16th century by the Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman, and the smallest of them according to modern boundaries. A southern triangle had previously been shown in a completely different position, south of Argo Navis, on a globe of 1589 by the Dutchman Petrus Plancius, along with a southern cross, but they were not the constellations we know today. The modern Triangulum Australe was first depicted in 1598 on a globe by Petrus Plancius and first appeared in print in 1603 on the Uranometria atlas of Johann Bayer.
 
The three main stars of Triangulum Australe are brighter than those of their northern counterpart, although the constellation is smaller. Navigators have named its brightest star Atria, a contraction of its scientific name Alpha Trianguli Australis.
tra

Triangulum Australe, with the alternative name Libella, the level, on Chart XX of Johann Bode’s Uranographia (1801). Bode followed Lacaille in showing a plumb bob attached to the triangle, thereby representing it as a surveyor’s level. Along with the compasses (Circinus) and a set square (Norma) it formed a group of surveying instruments in this part of the sky.
 
 
On his 1756 planisphere of the southern stars Lacaille referred to it as ‘le Triangle Austral ou le Niveau’ (‘niveau’ meaning level) and he even showed it with an attached plumb bob, indicating that he regarded it as representing a surveyor’s level. ‘Niveau’ was later Latinized to ‘libella’, as on Bode’s atlas shown here. Through some misreading, the historian R. H. Allen transferred the appellation ‘level’ to the nearby constellation Norma and termed that constellation the Level and Square (instead of the Rule and Square), thereby confusing generations of astronomers.
 
 
 
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