Andromeda Galaxy

Perched near the waist of the ill-fated princess Andromeda lies a majestic spiral galaxy. Visible to the naked eye under moonless, dark skies, the Andromeda Galaxy is one of the closest galaxies to our own Milky Way Galaxy (the Large Magellanic Cloudand Small Magellanic Cloud are among those of the Local Group that are even closer). It is home to an estimated 1 trillion stars and is substantially larger than the Milky Way.

The Andromeda Galaxy is one of the few galaxies that is approaching rather than receding from our galaxy, at about 100 kilometers per second. It is expected to eventually collide with the Milky Way in a few billion years, likely merging into one, larger elliptical galaxy.

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The Pegasus

[PEG-uh-suss]   Pegasus was the winged horse best known for his association with the Greek hero Bellerophon. The manner of the horse's birth was unusual, to say the least. Its mother was Medusa, the Gorgon, who in her youth was famed for her beauty, particularly her flowing hair. Many suitors approached her, but the one who took her virginity was Poseidon, who is both god of the sea and god of horses. Unfortunately, the seduction happened in the temple of Athene. Outraged by having her temple defiled, the goddess Athene changed Medusa into a snake-haired monster whose gaze could turn men to stone.

When Perseus decapitated Medusa, Pegasus and the warrior Chrysaor sprang from her body. The name Pegasus comes from the Greek word pegai, meaning 'springs' or 'waters'. Chrysaor's name means 'golden sword', in description of the blade he carried when he was born. Chrysaor played no further part in the story of Pegasus; he later became father of Geryon, the three-bodied monster whom Heracles slew.

Pegasus stretched his wings and flew away from the body of his mother, eventually arriving at Mount Helicon in Boeotia, home of the Muses. There, he struck the ground with his hoof and, to the delight of the Muses, from the rock gushed a spring of water which was named Hippocrene, 'horse's fountain'. The goddess Athene later came to see it.

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The Little Horse

The Little Horse

[eh-QUOO-lee-us]   This insignificant constellation, second-smallest in the sky, first appeared among the 48 constellations listed by the Greek astronomer Ptolemy in the second century AD. It was unknown to Aratus 400 years earlier. The actual inventor is unknown; it may have been Ptolemy himself, or one of his predecessors such as Hipparchus in the second century BC.

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The Ursa Major

[URR-suh MAY-jur]   Undoubtedly the most familiar star pattern in the entire sky is the seven stars that make up the shape popularly termed the Plough orBig Dipper, part of the 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. Ursa Major is the third-largest constellation.

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.

Callisto is usually said to have been the daughter of Lycaon, king of Arcadia in the central Peloponnese. She joined the retinue of Artemis, goddess of hunting. Dressed in the same way as Artemis, tying her hair with a white ribbon and pinning together her tunic with a brooch, 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.

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.

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The Sirius

From Orion, look south and to the east to find brilliant Sirius, as if one really needs directions to find the brightest star in the sky. Its name comes from the Greek word for “searing” or “scorching,” certainly appropriate for a star that shines at the bright end of the minus-first (−1.47) magnitude. Sirius is the luminary of the constellation Canis Major, the Greater Dog, which represents Orion’s larger hunting dog, and as such is commonly referred to as the “Dog Star.”

So great is its prominence that it has two “announcer stars” that from the mid-northern hemisphere rise before it, Procyon and Mirzam. Famed from times long past, the first glimpse of Sirius in dawn announced the rising of the Nile in ancient Egypt. (It no longer does because of precession, the 26,000-year wobble of the Earth’s axis.) Sirius is also part of a large asterism, the Winter Triangle, the other two stars of which areBetelgeuse in Orion and Procyon in the smaller dog, Canis Minor.

Because of its brilliance, Sirius is the champion of all twinklers, the effect caused by variable refraction in the Earth’s atmosphere. The star, a white class A (A1) hydrogen-fusing dwarf with a temperature of 9880 Kelvin, is bright in part because it is indeed rather luminous, 26 times more so than the Sun, but mostly because it is nearby, a mere 8.6 light years away, just double that of the closest star to the Earth (Alpha Centauri) and the fifth closest star system. Sirius is “metal rich,” its iron content perhaps double that of the Sun, most likely from some sort of elemental diffusion. With a radius of 1.75 solar (in agreement with the measured angular diameter) and a minimum equatorial rotation speed of 16 kilometers per second, Sirius rotates in under 5.5 days.

The star’s greatest claim to fame may be its dim eighth magnitude (8.44) companion, Sirius B, which is visually nearly 10,000 times fainter than the bright star, Sirius A. Sirius B, however, is actually the hotter of the two, a blue-white 24,800 kelvins. Though typically separated from each other by a few seconds of arc, Sirius B is terribly difficult to see in the glare of Sirius A. The only way the companion star can be both hot and dim is to be small, only 0.92 the size of Earth, the total luminosity (including its ultraviolet light) just 2.4 percent that of the Sun.

The two orbit each other with a 50.1 year period at an average distance of 19.8 Astronomical Units, aboutUranus’s distance from the Sun, a large orbital eccentricity carrying them from 31.5 AU apart to 8.1 AU and back again. They were closest in 1994 and will be again in 2044, while they will be farthest apart in 2019. From the orbit (and spectroscopic data), we find that Sirius A and B have respective masses of 2.12 and 1.03 times that of the Sun.

Sirius B is the chief member of a trio of classic white dwarfs, the others Procyon B and 40 Eridani B. Its high mass and tiny radius lead to an amazing average density of 1.7 metric tons per cubic centimeter, roughly a sugar cube. White dwarfs are the end products of ordinary stars like the Sun, tiny remnants that were once nuclear-fusing cores that have run out of fuel. Most are balls of carbon and oxygen whose fates are merely to cool forever. To have evolved first, Sirius B must once have been more massive and luminous than Sirius A. That its mass is now lower is proof that stars lose considerable mass as they die. Given the mass of the white dwarf and the 250 million year age of the system, Sirius B may once have been a hot class B3–B5 star that could have contained as much as 5 to 7 solar masses, the star perhaps losing over 80 percent of itself back into interstellar space through earlier winds.

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The Phoenix

[FEE-nix]   A constellation representing the mythical bird that supposedly was reborn from its own ashes. It is the largest of the 12 constellations invented at the end of the 16th century by the Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman.

The phoenix supposedly resembled a large eagle with scarlet, blue, purple, and gold plumage. Ovid in his Metamorphoses tells us that the phoenix lived for 500 years, eating the gum of incense and the sap of balsam. The death and rebirth of the phoenix has been seen as symbolizing the daily rising and setting of the Sun.

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The Fornax

[FOR-naks]   An obscure constellation introduced by the Frenchman Nicolas Louis de Lacaille after his trip to the Cape of Good Hope to observe the southern stars in 1751–52. It lies tucked into a bend in the riverEridanus.

Lacaille originally called it le Fourneau on his 1756 planisphere and depicted it as a chemist's furnace used for distillation. The name was Latinized to Fornax Chimiae on the 1763 edition of his planisphere. Bode, on his atlas, showed a far more elaborate set-up which he called Apparatus Chemicus. In 1845 the English astronomer Francis Baily shortened its name to Fornax in his British Association Catalogue, following a suggestion by John Herschel, and it has been known as that ever since.

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The Lyra

[LYE-ruh]   A compact but prominent constellation, marked by the fifth-brightest star in the sky, Vega. Mythologically, Lyra was the lyre of the great musician Orpheus, whose venture into the Underworld is one of the most famous of Greek stories. It was the first lyre ever made, having been invented by Hermes, the son of Zeus and Maia (one of the Pleiades). Hermes fashioned the lyre from the shell of a tortoise that he found browsing outside his cave on Mount Cyllene in Arcadia. Hermes cleaned out the shell, pierced its rim and tied across it seven strings of cow gut, the same as the number of the Pleiades. He also invented the plectrum with which to play the instrument.

The lyre got Hermes out of trouble after a youthful exploit in which he stole some of Apollo's cattle. Apollo angrily came to demand their return, but when he heard the beautiful music of the lyre he let Hermes keep the cattle and took the lyre in exchange. Eratosthenes says that Apollo later gave the lyre to Orpheus to accompany his songs.

Orpheus was the greatest musician of his age, able to charm rocks and streams with the magic of his songs. He was even reputed to have attracted rows of oak trees down to the coast of Thrace with the music of his lyre. Orpheus joined the expedition of Jason and the Argonauts in search of the golden fleece. When the Argonauts heard the tempting song of the Sirens, sea nymphs who had lured generations of sailors to destruction, Orpheus sang a counter melody that drowned the Sirens' voices.

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The Cygnus

[SIG-nus]   A popular name for Cygnus is the Northern Cross, and indeed its shape is far larger and more distinctive than the famous Southern Cross. In its cruciform shape the Greeks visualized the long neck, outstretched wings and stubby tail of a swan flying along the Milky Way, in which it is embedded. The mythographers tell us that the swan is Zeus in disguise, on his way to one of his innumerable love affairs, but his exact quarry is a subject of some disagreement.

One version of the tale says that Zeus seduced Queen Leda of Sparta in the form of a swan by the banks of the river Eurotas; with this story in mind, Germanicus Caesar refers to the swan as the 'winged adulterer'. Leda was the wife of King Tyndareus of Sparta, which considerably complicated the outcome because she also slept with her husband later the same night.

According to one interpretation, she gave birth to a single egg from which hatched the twins Castor andPolydeuces as well as Helen (later to become famous as Helen of Troy). The shell of this egg was said to have been put on display at a temple in Sparta, hanging by ribbons from the ceiling.

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The Pegasus

[PEG-uh-suss]   Pegasus was the winged horse best known for his association with the Greek hero Bellerophon. The manner of the horse's birth was unusual, to say the least. Its mother was Medusa, the Gorgon, who in her youth was famed for her beauty, particularly her flowing hair. Many suitors approached her, but the one who took her virginity was Poseidon, who is both god of the sea and god of horses. Unfortunately, the seduction happened in the temple of Athene. Outraged by having her temple defiled, the goddess Athene changed Medusa into a snake-haired monster whose gaze could turn men to stone.

When Perseus decapitated Medusa, Pegasus and the warrior Chrysaor sprang from her body. The name Pegasus comes from the Greek word pegai, meaning 'springs' or 'waters'. Chrysaor's name means 'golden sword', in description of the blade he carried when he was born. Chrysaor played no further part in the story of Pegasus; he later became father of Geryon, the three-bodied monster whom Heracles slew.

Pegasus stretched his wings and flew away from the body of his mother, eventually arriving at Mount Helicon in Boeotia, home of the Muses. There, he struck the ground with his hoof and, to the delight of the Muses, from the rock gushed a spring of water which was named Hippocrene, 'horse's fountain'. The goddess Athene later came to see it.

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The Cepheus

[SEE-fee-us]   Cepheus was the mythological king of Ethiopia. He was deemed worthy of a place in the sky because he was fourth in descent from the nymph Io, one of the loves of Zeus – and having Zeus as a relative was always an advantage when it came to being commemorated among the constellations. The kingdom of Cepheus was not the Ethiopia we know today, but stretched from the south-eastern shore of the Mediterranean southwards to the Red Sea, an area that contains parts of the modern Israel, Jordan and Egypt. Ptolemy described him as wearing the tiara-like head-dress of a Persian king.

Cepheus was married to Cassiopeia, an unbearably vain woman whose boastfulness caused Poseidon to send a sea monster, Cetus, to ravage the shores of Cepheus's kingdom. Cepheus was instructed by the Oracle of Ammon to chain his daughterAndromeda to a rock in sacrifice to the monster. She was saved by the hero Perseus, who killed the monster and claimed Andromeda for his bride.

King Cepheus laid on a sumptuous banquet at his palace to celebrate the wedding. But Andromeda had already been promised to Phineus, brother of Cepheus. While the celebrations were in progress, Phineus and his followers burst in, demanding that Andromeda be handed over, which Cepheus refused to do. The dreadful battle that ensued is described in gory detail by Ovid in Book V of his Metamorphoses. Cepheus retired from the scene, muttering that he had done his best, and left Perseus to defend himself. Perseus cut down many of his attackers, turning the remainder to stone by showing them the Gorgon's head.

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The Capricornus

[CAP-rih-CORN-us]   Capricornus is an unlikely looking creature, with the head and forelegs of a goat and the tail of a fish. The constellation evidently originated with the Sumerians and Babylonians, who had a fondness for amphibious creatures; the ancient Sumerians called it SUHUR-MASH-HA, the goat-fish. But to the Greeks, who named it Aegoceros (goat-horned), the constellation was identified with Pan, god of the countryside, who had the horns and legs of a goat.

Pan, a playful creature of uncertain parentage, spent much of his time chasing females or sleeping it off with a siesta. He could frighten people with his loud shout, which is the origin of the word 'panic'. One of his offspring was Crotus, identified with the constellation Sagittarius. Pan's attempted seduction of the nymph Syrinx failed when she turned herself into a handful of reeds. As he clutched the reeds the wind blew through them, creating an enchanting sound. Pan selected reeds of different lengths and stuck them together with wax to form the famous pipes of Pan, also called the syrinx.

Pan came to the rescue of the gods on two separate occasions. During the battle of the gods and the Titans, Pan blew a conch shell to help put the enemy to flight. According to Eratosthenes his connection with the conch shell accounts for his fishy nature in the sky, although Hyginus says somewhat absurdly that it is because he hurled shellfish at the enemy. On a later occasion, Pan shouted a warning to the gods that the monster Typhon was approaching, sent by Mother Earth (Gaia) against the gods. At Pan's suggestion the gods disguised themselves as animals to elude the monster. Pan himself took refuge in a river, turning the lower part of his body into a fish.

Zeus grappled with Typhon, but the monster pulled out the sinews from Zeus's hands and feet, leaving the god crippled. Hermes and Pan replaced the sinews, allowing Zeus to resume his pursuit of Typhon. Zeus cut down the monster with thunderbolts and finally buried him under Mount Etna in Sicily, which still belches fire from the monster's breath. In gratitude for these services, Zeus placed the image of Pan in the sky as the constellation Capricornus.

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