Aurora

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The Gates of Dawn
Herbert James Draper
(1864–1920)
‘Far in the crimsoning east wakeful Dawn threw wide the shining doors of her rosefilled chambers’ wrote Ovid in the Metamorphoses, and that’s what we see her doing in the painting above by the English artist Herbert James Draper.
 
Aurora was the Roman goddess of the dawn (her Greek equivalent was Eos), but in astronomy her name is associated with the aurora borealis and australis, the northern and southern lights.
 
The first person to apply the name aurora to this phenomenon was Galileo Galilei in 1616. The additional distinction between ‘borealis’ meaning north and ‘australis’ meaning south came later when explorers such as Captain Cook first ventured far into the southern hemisphere in the 1770s and it was realized that there were southern aurorae as well as northern ones.
 
Hence the term aurora borealis actually means northern dawn, which is a good description of it as seen from latitudes such as England, where only the top of the activity can usually be seen low on the northern horizon like a false dawn.
 
In Greek mythology Eos was the sister of the Sun god Helios, for whose chariot she threw open the gates of heaven each morning, and also the sister of Selene, the Moon goddess. She was said to be mother of the stars, including the Morning Star (the popular name for planet Venus). The mythographers described her as ‘rosy-fingered’ and ‘saffron-robed’ in reference to the pink tinge of the dawn sky. She was for a time a lover of Orion.
 
We now know that aurorae are glows of the upper atmosphere around the poles caused by atomic particles from the Sun. But in Roman times aurorae were interpreted as omens of disaster, similar to or even worse than comets. Pliny the Elder, a Roman writer of the first century AD, described aurorae as ‘them which there is no presage of woe more calamitous to the human race, a flame in the sky, which seems to descend to the Earth on showers of blood’.
 
This description might at first seem puzzling, since aurorae are predominantly green in colour; but as seen from more southerly latitudes, such as the Mediterranean region, only the upper, red-coloured portions would be visible above the northern horizon. The red colour is particularly prominent in the strongest aurorae, and it is only those that will be seen as far south as the Mediterranean.
 
A blood-red aurora would inevitably raise fears of war and death, but it might also be mistaken for the glow of a fire. Such a mistake was reportedly made during the reign of Emperor Tiberius (AD 14—37) by Roman fire brigades who rushed to the port of Ostia, thinking it to be burning down. But it was in fact a red aurora. More recently, a major aurora in January 1938 had fire brigades dashing in search of imaginary fires throughout Europe as far south as Austria and Switzerland.
 
People of the far north have many legends about the aurorae. An attractive selection can be found on this page by Ingrid Sandahl of the Swedish Institute of Space Physics:
 
 
 
© Ian Ridpath. All rights reserved
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The Milky Way

The Milky Way is not, of course, a constellation, but a band of faint light crossing the sky, consisting of countless distant stars. Aratus wrote of the sky being ‘cleft all around by a broad band’ which he called Γάλα (Gala, the Greek for milk). Eratosthenes called it Κύκλος Γαλαξίας (Kýklos Galaxías), the circle of milk. Ptolemy in the Almagest spelled the name γαλακτίας (galaktías).
 
The Roman writer Manilius compared the Milky Way to the luminous wake of a ship. Ovid in his Metamorphoses described it as a road lined on either side by the houses of distinguished gods – ‘the Palatine district of high heaven’, he termed it. Along this road the gods supposedly travelled to the palace of Zeus.
 
Eratosthenes tells us that the Milky Way was the result of a trick played by Zeus on his wife Hera so that she would suckle his illegitimate son Heracles and hence make him immortal. Hermes laid the infant Heracles at Hera’s breast while she was asleep, but when she woke and realized who the baby was – perhaps by the strength with which he sucked – she pushed him away and her milk squirted across the sky to form the Milky Way.
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Tintoretto’s painting titled The Origin of the Milky Way illustrates the myth of the baby Heracles being placed at the breast of Hera, with her milk spilling out to form the Milky Way. However, unlike in the traditional version recounted by Eratosthenes, it seems that here it is not Hermes but Zeus himself who is placing the baby at Hera’s breast, for in the background we see his eagle carrying a thunderbolt, as well as the peacocks of Juno. (Photo © The National Gallery, London.)
 
 
Manilius listed various explanations for the Milky Way that were current in his day, both scientific and mythological. One suggestion was that it is the seam where the two halves of the heavens are joined – or, conversely, where the two halves are coming apart like a split in the ceiling, letting in light from beyond. Alternatively, said Manilius, it might be a former path of the Sun, now covered in ash where the sky was scorched. Some thought that it could mark the route taken by Phaethon when he careered across the sky in the chariot of the Sun god, Helios, setting the sky on fire (see Eridanus). Yet again, noted Manilius, it could be a mass of faint stars, an idea attributed to the Greek philosopher Democritus of the fifth century BC, which we now know to be correct. Finally, on a quasi-religious note, Manilius suggested that the Milky Way could be the abode of the souls of heroes who had ascended to heaven.
 
To the Arabs of the Middle Ages the Milky Way was known as al-madjarra, from a word meaning a place where something is pulled or drawn along, such as a cart track. It seems that Arab scientists such as al-Bīrūnī (973–1048) understood the Milky Way’s true nature as a distant mass of stars.

Chinese associations
In Chinese astronomy, the Milky Way was Tianhe, the Celestial River, also translatable as River of Heaven. Nine stars in Cygnus, including Deneb, represented Tianjin, a ford across the river at a point where it appeared to be particularly shallow; the impression of shallowness comes about because a dark cloud of dust in the local spiral arm of our Galaxy called the Great Rift obscures part of the Milky Way in this region.
 
 
© Ian Ridpath. All rights reserved

Vulpecula – The Fox

Genitive: Vulpeculae
Abbreviation: Vul
Size ranking: 55th
Origin: The seven constellations of Johannes Hevelius
 
A constellation introduced in 1687 by the Polish astronomer Johannes Hevelius, who depicted it as a double figure of a fox, Vulpecula, carrying in its jaws a goose, Anser. Since then the goose has flown (or been eaten), leaving just the fox. Hevelius placed the fox near two other hunting animals, the eagle (the constellation Aquila) and the vulture (which was an alternative identification for Lyra). He explained that the fox was taking the goose to neighbouring Cerberus, another of his inventions – although this part of the tableau has been spoilt, as Cerberus is now obsolete.
 
Hevelius himself was somewhat inconsistent in his naming of this constellation. In his star catalogue he named the pair ‘Vulpecula cum Ansere’, the fox with goose, but showed them separately as ‘Anser’ and ‘Vulpecula’ on his Firmamentum Sobiescianum star atlas. Others preferred the slightly amended title fox and goose.
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The fox and the goose shown as ‘Vulpec. & Anser’ on the Atlas Coelestis of John Flamsteed (1729). The Fox and Goose is a traditional pub name in Britain. For the original depiction by Hevelius, see here.
 
 
Vulpecula contains no named stars and has no legends. Its brightest star, Alpha Vulpeculae of magnitude 4.4, is the only one honoured with a Greek letter, allocated by Francis Baily in his British Association Catalogue of 1845.
 
Vulpecula is notable for the Dumbbell Nebula, reputedly the most conspicuous of the class of so-called planetary nebulae. The Dumbbell Nebula consists of gas thrown off from a dying star; it takes its name from the double-lobed structure, like a bar-bell, as seen on long-exposure photographs.
 
On the border with Sagitta is an asterism known as Brocchi’s Cluster, or more popularly the Coathanger because of its distinctive bar-and-hook shape. It consists of ten stars of 5th magnitude and fainter and is just visible to the naked eye under good conditions; it was first mentioned by the Arab astronomer al-ūfī in his Book of the Fixed Stars, written in AD 964.
 
None of the stars of Vulpecula featured in the Chinese constellation system, although they did briefly form part of the now-obsolete river Tigris, invented earlier in the 17th century by the Dutch astronomer Petrus Plancius.
 
 
© Ian Ridpath. All rights reserved

Volans – The Flying Fish

Genitive: Volantis
Abbreviation: Vol
Size ranking: 76th
Origin: The 12 southern constellations of Keyser and de Houtman
 
One of the 12 new constellations introduced at the end of the 16th century by the Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman. Volans represents a real type of fish found in tropical waters that can leap out of the water and glide through the air on wings. Sometimes the fish landed on the decks of ships and were used for food. In the sky the flying fish is imagined being chased by the predatory Dorado, as happens in reality.
 
The constellation was first depicted in 1598 on a globe by the Dutchman Petrus Plancius under the name Vliegendenvis. Bayer in 1603 called it Piscis Volans, the Latin title by which it became generally known until the mid 19th century. In 1844 the English astronomer John Herschel proposed shortening itto just Volans. Francis Baily adopted this suggestion in his British Association Catalogue of 1845, and it has been known as Volans ever since.
 
Its brightest stars are of only fourth magnitude, none are named, and there are no legends associated with it.
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Volans, under its original name Piscis Volans, shown leaping against the side of the ship Argo on Chart XX of the Uranographia of Johann Bode (1801).
 
 
 
© Ian Ridpath. All rights reserved

Virgo – The Virgin

Genitive: Virginis
Abbreviation: Vir
Size ranking: 2nd
Origin: One of the 48 Greek constellations listed by Ptolemy in the Almagest
Greek name:Παρθένος (Parthenos)
 
Virgo is the second-largest constellation in the sky, exceeded only by the much fainter Hydra. The Greeks called the constellation Παρθένος (Parthenos), which is the name Ptolemy gave in the Almagest. She is usually identified as Dike, goddess of justice, who was daughter of Zeus and Themis; but she is also known as Astraeia, daughter of Astraeus (father of the stars) and Eos (goddess of the dawn). Virgo is depicted with wings, reminiscent of an angel, holding an ear of wheat in her left hand (the star Spica).
 
Dike features as the impartial observer in a moral tale depicting mankind’s declining standards. It was a favourite tale of Greek and Roman mythologists, and its themes still sound familiar today.
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Virgo depicted in the Atlas Coelestis of John Flamsteed (1729). In her right hand
she carries a palm frond, while in her left hand she holds an ear of wheat marked
by the bright star Spica.

 
 
Dike was supposed to have lived on Earth in the Golden Age of mankind, when Cronus ruled Olympus. It was a time of peace and happiness, a season of perennial spring when food grew without cultivation and humans never grew old. Men lived like the gods, not knowing work, sorrow, crime, or war. Dike moved among them, dispensing wisdom and justice.
 
Then, when Zeus overthrew his father Cronus on Olympus, the Silver Age began, inferior to the age that had just passed. In the Silver Age, Zeus shortened springtime and introduced the yearly cycle of seasons. Humans in this age became quarrelsome and ceased to honour the gods. Dike longed for the idyllic days gone by. She assembled the human race and spoke sternly to them for forsaking the ideals of their ancestors. ‘Worse is to come’, she warned them. Then she spread her wings and took refuge in the mountains, turning her back on mankind. Finally came the Ages of Bronze and Iron, when humans descended into violence, theft, and war. Unable to endure the sins of humanity any longer, Dike abandoned the Earth and flew up to heaven, where she sits to this day next to the constellation of Libra, which some see as the scales of justice.
 
Other identifications
There are other goddesses who can claim identity with Virgo. One is Demeter, the corn goddess, who was daughter of Cronus and Rhea. By her brother Zeus she had a daughter, Persephone (also called Kore, meaning ‘maiden’). Persephone might have remained a virgin for ever had not her uncle, Hades, god of the Underworld, kidnapped her while she was out picking flowers one day at Henna in Sicily. Hades swept her aboard his chariot drawn by four black horses and galloped with her into his underground kingdom, where she became his reluctant queen.
 
Demeter, having scoured the Earth for her missing daughter without success, cursed the fields of Sicily so that the crops failed. In desperation she asked the Great Bear what he had seen, since he never sets, but since the abduction had taken place during the day he referred her to the Sun, who finally told her the truth.
 
Demeter angrily confronted Zeus, father of Persephone, and demanded that he order his brother Hades to return the girl. Zeus agreed to try; but already it was too late, because Persephone had eaten some pomegranate seeds while in the Underworld and, once having done that, she could never return permanently to the land of the living. A compromise was reached in which Persephone would spend half (some say one-third) of the year in the Underworld with her husband, and the rest of the year above ground with her mother. Clearly, this is an allegory on the changing seasons.
 
Eratosthenes offers the additional suggestion that Virgo might be Atargatis, the Syrian fertility goddess, who was sometimes depicted holding an ear of corn. But this seems to be a mistake because Atargatis is identified with the constellation Piscis Austrinus. Hyginus, more plausibly, equates Virgo with Erigone, the daughter of Icarius, who hanged herself after the death of her father. In this story, Icarius became the constellation Boötes, which adjoins Virgo to the north, and Icarius’s dog Maera became the star Procyon (see Boötes and Canis Minor).
 
Eratosthenes and Hyginus both name Tyche, the goddess of fortune, as another identification of Virgo; but Tyche was usually represented holding the horn of plenty (cornucopia) rather than an ear of grain. In the sky, the ear of corn is represented by the first-magnitude star Spica, a Latin name meaning ‘ear of grain’. The star’s name in Greek, Στάχυς (Stachys), has the same meaning. Spica lies 250 light years away.
 
Stars of Virgo
Beta Virginis is called Zavijava, from an Arabic name meaning ‘the angle’; in the Almagest, Ptolemy located this star on the top of Virgo’s left wing. Gamma Virginis, also in the left wing, is called Porrima, after a Roman goddess. According to Ovid in his Fasti, Porrima and her sister Postverta were the sisters or companions of the prophetess Carmenta. Porrima sang of events in the past, while Postverta sang of what was to come.
 
Epsilon Virginis, on Virgo’s right wing, is named Vindemiatrix, from the Latin meaning ‘grape-gatherer’ or ‘vintager’, because its first visible rising before the Sun in August marked the beginning of each year’s vintage. Ovid in his Fasti tells us that this star commemorates a boy named Ampelus (the Greek word for ‘vine’) who was loved by Dionysus, god of wine. While picking grapes from a vine that trailed up an elm tree, Ampelus fell from a branch and was killed; Dionysus placed him among the stars. This star’s original Greek name, Προτρυγητήρ (Protrygeter), also means ‘grape gatherer’, the same as in Latin. Its importance as a calendar star is demonstrated by the fact that it was one of the few stars named by Aratus and, at third magnitude, was far fainter than the others.
 
Virgo, incidentally, contains the autumnal equinox, the point at which the Sun crosses the celestial equator heading south; this occurs on September 22 or 23 each year. In ancient times the autumnal equinox lay in Libra, and hence it is still sometimes referred to as ‘the first point of Libra’. However, because of the effect of precession, the autumnal equinox crossed the modern constellation boundary from Libra into Virgo around 730 BC. It continues to move, and will eventually reach Leo in AD 2439.

Chinese associations
In Chinese astronomy, northern Virgo was part of an area called Taiwei, a court or palace of the Emperor, where the Privy Council met in camera for administrative and legal discussions. This court, also known as the Supreme Palace Enclosure, included parts of Coma Berenices and LeoTaiwei was not in itself a constellation but an area of sky in which events or characters with a common theme were depicted. Being an enclosure it was bounded by walls on the east and west, each marked out by a chain of five stars. The left (eastern) wall started with Eta Virginis and continued northwards via Gamma (Porrima), Delta, and Epsilon Virginis (Vindemiatrix) to Alpha Comae Berenices. The other wall started at Beta Virginis (Zavijava) and ran into Leo, ending at Delta Leonis. Within Taiwei, in the area we now consider the ‘bowl’ of Virgo, various faint stars were seen as representing groups of officials and dignitaries such as Sangong (three stars representing seats for three excellencies), Jiuqing (seats for nine ministers, although it consisted of only three stars) and Yezhe, a court usher, represented by a single star, probably 16 Virginis.
 
Spica and Zeta Virginis formed Jiao, the horn of the Blue Dragon. Jiao, ‘horn’, was also the first of the 28 Chinese lunar mansions. Since the ecliptic passed between the two stars of Jiao the pair were seen as a gateway for the Sun, Moon, and planets (there are many such gateways in the Chinese sky). Confusingly, two stars to the south of Spica, 53 and 69 Virginis, were also described as a gate, Tianmen, even though they were aligned nearly parallel to the ecliptic and so the Sun could not pass between them.
 
Two other stars at right angles to the line between Spica and Zeta Virginis, identities uncertain but close to the ecliptic, formed Pingdao, a flat, straight road for the Sun, Moon, and planets. To the right of these a single star, possibly Theta Virginis, was known as Jinxian, representing people of outstanding achievement being recommended for honours or awards. North of Zeta Virginis, two stars (probably Tau and either 78 or Sigma Virginis) were Tiantian, the heavenly fields, in which the Emperor instituted ploughing every spring before the year’s crops were sown.
 
The stars Lambda, Kappa, Iota, and Phi Virginis formed Kang, the neck of the Blue Dragon, and also the name given to the second lunar mansion. Kang was also visualized in another way more relevant to Chinese society, as a government department administering various home affairs. Near Kang was the similarly named Kangchi, representing a lake with sailing boats. According to Sun and Kistemaker, Kangchi originally consisted of 110, 109, and Mu Virginis, plus three other stars in Libra. Over time, though, it was moved north, first to six stars straddling the border between Virgo and Boötes and finally ending up as four faint stars in Boötes alone.
 
 
© Ian Ridpath. All rights reserved