By Marilyn Morgan
Ancient Impressions of Jupiter
What was it like to live as a very early human, thousands of years ago? The world must have seemed mysterious and frightening, as well as wondrous and fantastic. The earliest people could not have failed to be aware of the boundary between night and day, and they must have gazed at the night sky with awe as humans still do. Curiosity about the world had to be secondary to survival, but as societies became more settled and more complex, and humans more interdependent, the desire for explanations became stronger. The blazing fireball that rose overhead each day would have been welcome for its light and warmth, and its daily disappearance would have caused considerable anxiety (would it come back again?). Nightfall, with its deep, velvet-black canopy sprinkled with brilliant lights, was no doubt even more mysterious. Imagine how our Moon might have appeared, sometimes as a bright disc, sometimes as a sliver, and sometimes not showing up at all. Who first realized that the Moon was not many different things, but one object that changed appearance on different nights? It would have taken a certain level of observational ability, a certain level of intelligence, and even courage, to look upward and notice the regular behavior of the brilliant, mysterious lights in the sky.
There were ancient observers who gradually gained an understanding of the differences between the many lights in the heavens that moved in groups across the sky canopy and the few bright lights that moved one way, then another, wandering about the sky. These odd wandering lights had a different appearance, too: they looked more solid, even disc-like, than the sparkling fixed lights. The earliest observers had no idea that they were looking at planets other worlds moving in orbits about the Sun. To humans observing from Earth, the brilliant discs seemed to wander through the fixed stars that moved majestically across the celestial field. Long before it was given the name we now call it, Jupiter was recognized as prominent among the wandering lights.
Curiosity requires explanations, and human imagination filled the void. There were those who told stories that convincingly explained the strange goings on in the heavens. In these old days, shamans, priests, and other revered persons assured their listeners that the objects we know as the Sun, the Moon, the stars, and the planets were beings who resembled earthly creatures. But these celestial figures, so it was said, had powers far beyond those of earthly beings; they in fact were divine, gods with amazing strength and oversized personalities. Such gods behaved extravagantly and grandly, engaged in monumental struggles, and made up their own rules. There were also astonishing beasts in the heavenly landscape, or beings who were part human and part animal.
People did not realize how far away the heavens really were. It seemed reasonable to them that the sky was a canopy whose edges touched the surface of Earth, and of course the heavenly creatures could go back and forth from Earth to the sky. All these elements added up to satisfying explanations of the world that humans could see and faraway places they could imagine as well. The Sun might be a chariot drawn by horses carrying a shining god across the sky every day. Or a storyteller would assert that a great monster ate up the Moon in stages and then began all over again, which is why the Moon changes shape throughout the month. The ancient Egyptians had an elaborate belief system in which the Pharaoh was identified with the Sun; it was thought that the Pharaohs spirit would ascend heavenward after he died and he would live on as a star.
Each group of people each culture made up their own stories, which are generally referred to as myths. Ancient myths explained natural happenings and also contained moral lessons. For example, the Greek story of Apollo and Phaeton demonstrates the dangers of taking on too much responsibility too early. In that story, the Sun king Apollos son Phaeton asks to drive the Suns chariot through the sky, but the boy cannot control the chariot because he is too young and inexperienced. The result is that Earth becomes parched with drought in some places and frozen in others. This episode very likely explained a season of drought or a period of unusually cold weather, but it also taught the members of that community about the problems of granting a child's wish too hastily. Even today, people read and study mythology for insights into social and psychological truths that apply to human behavior now as they did thousands of years ago.
Early Civilizations and Jupiter
Eventually, our ancestors decided that something so grand and beautiful as the sky and these strange wandering lights the planets, the stars, the Sun and Moon must mean something more. They believed that the lights of the planets moved in strange ways because they were alive or were moved by spiritual forces, and were trying to communicate with us here on Earth. A wise man or woman would attempt to interpret the heavens to tell the future, decide arguments between tribe members, or provide answers to questions that people in the tribe asked. They attempted to read what the gods were saying in the sky and then interpreted the message for their people.
Once people started living in organized communities, the role of these wise men and women became an important profession. The first astronomers in the great civilizations of Sumeria in the Middle East, in Egypt, and in China were priests and soothsayers whose job it was to observe and predict celestial events and tell the king and his subjects what would happen. Humankind learned more and more about predicting natural occurrences when the rainy season would come, for example and how to live within this great scheme of things the best time for planting, and when one should store food for the winter. Many societies developed reasonably accurate calendars. Some early observers recorded solar and lunar eclipses and the appearance of comets. Practical concerns such as navigation, agriculture, and timekeeping were all tied in with observations of the heavens.
But people in these very early times did not imagine that Earth rotated in empty space and orbited the Sun. They naturally only trusted their senses, and so they believed Earth was immobile. The Sun must revolve around Earth, they thought, along with all the other celestial objects.
Since there were no telescopes back then, there were only a few things these official stargazers could observe about any of the planets: where the planet moved in the sky, how fast it moved, and its brightness. Astrologers attempted to tell the future and attribute meaning to what they saw in the sky. Other than the Sun and Moon, Jupiter and Venus are the two brightest objects in the sky, and so they were generally thought to bring good luck. Mars and Saturn were believed to bring bad luck or to be a sign of evil, probably because they are dimmer. Mars also appears red, the color of blood, and it was associated with war.
In many different cultures, the planet we know as Jupiter was named after the king of the local gods and often after the sky god of that region. The Romans called this god Jupiter; the Greeks called him Zeus, god of lightning and the sky; and the Germanic tribes called him Donar and later, Thor, both gods of thunder. When the seven-day calendar was invented, the days were named after the planets. Jupiter was considered to rule or in some way influence Thursday, German for Thors day. Jupiter's connection with Thursday is more obvious in the romance languages of French, Spanish, and Italian in those languages that day is called Jeudi, Jueves, and Giovedi.
The giant planet was crowned after such an important god not only because of its brightness, but perhaps also because it moved through one of the 12 constellations each year, thought to be a sign of its power. The ancient astronomer priests hit on a truth, however, since not only is Jupiter king of the sky in brightness, but we now know it is the king of our Solar System, for it is the largest planet. These first astronomers probably never dreamed that Jupiter was such a giant world; so large it could contain the mass of hundreds of Earths. Planet Jupiter's association with a god of lightning is also interesting, since we now know that lightning does exist on Jupiter.
In Greek and Roman mythology, the kingly god was notorious for having many lovers. Planet Jupiter also attracts a huge number of followers not only its moons, but numerous captured asteroids, called the Trojans, which orbit with the planet, and even a number of comets (the comet Shoemaker-Levy 9 9, which crashed into Jupiter in 1994, was not unusual in that it was orbiting Jupiter, but unusual in that we saw it hit the planet). Jupiter's moons are named for the many goddesses and mortals abducted by Jupiter/Zeus, an appropriate choice since the moons of Jupiter are indeed caught in its gravitational pull.
Some early civilizations were so influenced by the Sun, Moon, stars, and planets that they felt moved to pattern their entire society after the order they saw in the sky. In Sumeria, the city itself was laid out in the same order that the astronomers imagined the planets moved through the heavens, and each profession was assigned a ruling planet. The prime minister represented Jupiter, and this began Jupiter's association with justice and law. This idea spread to other cultures, as even the distant Scandinavians honored their version of Jupiter, Thor, when they convened their assembly beginning on Jupiter's day, Thursday. Thors hammer is still used today to bring order in courts, when the judge bangs the gavel.
As time went on, the priests who interpreted the sky became very powerful. And no wonder, since everyone believed that they read what the gods were saying in the sky whatever they told the people and their ruler was believed to be true since their gods sent the message. In some civilizations, the astronomer priests watched for signs in the heavens to tell them when to make sacrifices. Sometimes the king himself was sacrificed, and on a somewhat regular basis all on the word of the powerful sky-watching priests. For example, at one time, every king in Malabar in ancient India could only rule for the 12 years it took Jupiter to make its way through all the zodiac signs. Once Jupiter reached the sign of Cancer, the fatal time had come, according to the priests. They insisted that the king must commit a ritual, public suicide just as the planet, from our point of view on Earth, appeared to move backwards. In many early cultures, ceremonial murder of the king or other human beings was a common occurrence. Often such practices continued until a new young king, who may have been tutored abroad or simply cherished life above tradition, rejected such claims of divine commands from the astronomer priests and had them either dismissed or executed.
Other early cultures ideas about the heavens were usually less bloody, although they still differed widely, and literature that survives today reflects this. The Jewish people, for example, were content to believe that God created the heavens the Torah doesn't name or categorize the lights in the sky or explain at much length how they move and why. The Greeks, on the other hand, eventually created an entire philosophy of how the heavens were assembled. Aristotle, who lived in the third century BCE, proposed that Earth was the center of the Universe and above it the Moon, Sun, and planets orbited Earth, held in place by crystal spheres. Higher than all were the fixed stars, which also revolved around Earth, all embedded in the outermost sphere. [illustration of Aristotles spheres] Aristotle also claimed that while Earth was corruptible and imperfect, the heavenly objects were perfect and not made of the four elements of the world (believed to be fire, water, air, and earth) but rather of an entirely different element called quintessence or ether, which was also perfect. Aristotle's views were commonly accepted in Europe until the 16th century.
Observation of the sky and the planets was an absolute necessity for these early civilizations, so that they could track important information about the seasons and maintain an accurate calendar. But many misconceptions and superstitions also came along with that knowledge. Those intelligent and learned first astronomers knew there had to be some purpose to a bright, beautiful, wandering heavenly object like Jupiter, and they tried their best to piece out the truth. But many thousands of years had to go by before we would find out that Jupiter was much more than just a bright light above us.
The Mythology of Jupiter and Its Moons
The custom of giving the names of the gods and heroes of antiquity to newly observed celestial objects originated in the 17th century. After the sensational discovery of Jupiter's four large moons by Galileo Galilei in 1610, the German astronomer Simon Marius proposed, in 1614, that the moons be named after Io, Europa, Ganymede, and Callisto all mythological figures associated with the god Jupiter. (It was actually the astronomer Johannes Kepler who had suggested these names to Marius in 1613). Most of the other moons names were decided in just the last few decades.
New moons of Jupiter are now being discovered on a fairly regular basis. Astronomers found 23 tiny natural satellites orbiting the giant planet in 2003. Newly discovered moons are given temporary descriptive names, such as S/2000 J2. When accepted by the astronomical community, the satellite will receive its official name.
Here are the ancient stories behind the names given to Jupiter and 16 of its moons:
Jupiter is the Roman name for the god Zeus of Greek mythology. [painting of Zeus with scepter in the form of lightning] Greek mythology is older and has many more stories than Roman mythology, so most of the stories about Jupiter's moons mention Zeus instead. Jupiter/Zeus was the king of the sky and Earth and all the Olympian gods. He was also known as the god of justice. He was named king of the gods in the special meeting that followed his overthrow of the god Cronus (Saturn in Roman mythology) and the Titans. Zeuss wife was the goddess Hera, who was very jealous of the attention that Zeus paid to other goddesses and women. In the Roman version, Jupiter's wife was named Juno. Early in the planning stages of the Galileo mission, there was a proposal to name the spacecraft Juno, since the spacecraft in effect would be watching over Jupiter as well as keeping an eye on its moons (named after Jupiter's lovers), just as Jupiter's mythological goddess-wife did.
The Four Galilean Moons:
Io was a beautiful priestess of the Greek goddess Hera. When Zeus fell in love with Io, he transformed himself into the shape of a dark cloud to hide himself from his jealous wife. However, Hera looking down on Earth noticed the small cloud and suspected that it was one of the tricks of her husband. She decided to check the true nature of this cloud. When Hera approached, Zeus transformed Io into a white cow to avoid his wifes anger. But Hera guessed his trick and asked to have the cow as a gift. Zeus could not refuse such a little gift without giving himself away. So Hera tied up the poor cow and sent her faithful servant Argus to watch over Io. Argus had a hundred eyes and only a few were ever closed at any time. To free Io, Zeus sent his son Hermes to sing and tell boring stories to make Argus sleep with all his eyes. Hermes told so many stories that finally Argus closed his hundred eyes. Then Hermes killed Argus and released Io. When Hera discovered what had happened, she was so furious that she sent a vicious gadfly to sting the cow forever. To honor the memory of her faithful servant, Hera put the hundred eyes of Argus on the tail of the peacock, her favorite bird, where the eyes could no longer see but would beautifully decorate the tail. Meanwhile, Io was still a prisoner in the shape of a cow and could not escape the malicious gadfly. Finally, after Jupiter/Zeus vowed not to pursue Io, Juno/Hera released her. Io settled in Egypt, becoming the first queen of Egypt. Europa
Europa was a beautiful princess. Her father was Agenor, the Phoenician king of the city of Tyre. Zeus fell in love with Europa after seeing her gathering flowers by the sea. Zeus changed his form into that of a magnificent white bull and appeared at the seashore where Europa was playing with her maidens. The great bull walked over to where Europa stood and knelt at her feet. The appearance and movements of the bull were so gentle that Europa spread flowers about its neck and dared to climb on its back. Suddenly the bull rushed into the sea with Europa still on its back. Only then did Zeus reveal his true identity and took Europa to the Mediterranean island of Crete. There Zeus cast off the shape of the white bull and made Europa his bride and the first queen of Crete. Zeus later reproduced the shape of the magic white bull in the stars, in the constellation Taurus.
Ganymede, the son of King Tros, was a beautiful Trojan boy who was so handsome that Zeus himself desired him for a companion. Disguised as an eagle, Zeus flew down to Earth and carried him off to Mount Olympus. There Ganymede was made Zeus's cupbearer, bringing him and the other gods and goddesses the ambrosia drink that gave them eternal youth. King Tros was compensated for this loss with a golden vine, two fine horses, and the assurance that his son had become immortal and therefore exempt from the miseries of old age. Zeus set Ganymedes image among the stars as Aquarius, the water-carrier.
Callisto was a river goddess. Her great grandfather was the river god Inachus, and her father was Lycaon. Callisto avoided the companionship of the young boys and gods who wanted to be with her, for she wanted to be like her patron Artemis, the goddess of the hunt. Callisto was the favorite companion of Artemis. She accompanied the goddess on the hunt, helping her and looking after her needs.
According to the Roman poet Ovid, one day as Callisto was returning from the hunt, she lay down to rest in a thick grove of trees. Zeus saw how beautiful she was and that she was alone, and decided she was a conquest worth the danger of his wifes wrath. Knowing that Callisto was a follower of Artemis, Zeus tricked her by appearing to her as the goddess. Callisto was delighted to see her mistress and was receptive to her kisses and embraces. Zeus gave away his disguise and ravaged Callisto, who tried to resist, but Zeus was stronger. From their encounter, Callisto bore a son, Arcas.
Hera learned of her husbands liaison with Callisto and saw the birth of Arcas as a further insult. She turned Callisto into a bear in order to strip her of the beauty that Zeus had so appreciated. When Arcas was 15 years old, he was out hunting and met the bear that was his mother. She recognized him and began to approach him, but he didn't know her and prepared to throw his javelin. Zeus saw what was happening and turned them into two neighboring constellations. Callisto was transformed into the constellation Ursa Major (Great Bear) and Arcas into Ursa Minor (Little Bear). Hera was angry that her rival and rivals son should be displayed in the night sky for all to see, so she made the sea god Poseidon agree that he would never let the two touch his waters.
The Inner Moons
Between the large Galilean moons and giant Jupiter are four small moons: Metis, Adrastea, Amalthea, and Thebe. Voyager discovered all in 1979 except for Amalthea, which was discovered in 1892. Nearly all of the stories behind their mythological names are on the theme of Jupiter's early life.
Zeus visited Metis, a Titaness, when he was very young and she gave him counsel on how to overthrow his father Cronos. Her name means knowledge and she is described by Hesiod as she who knows most of gods and mortal men. Later when Zeus became king of the gods, he seduced Metis. Some stories even say she was Zeus's first wife, before Hera. But a prophecy said that she was fated to bear a son who would overthrow Zeus. When she became pregnant, Zeus followed the advice of his grandparents, Uranus and Gaia, and swallowed her whole in order to avoid the fate of being overthrown. Later, Athena was born out of the head of Zeus. She is presumably the child whom Metis would have borne. As the closest moon to Jupiter, Metis is aptly named, since it seems most in danger of being swallowed by the huge planet.
Adrastea figured in Zeus's early life, too, although Zeus had a daughter also named Adrastea (see Ananke's myth below). When Zeus was just a baby, his mother Rhea had to hide him from his father Cronus. That was because Cronus was told one of his offspring would overthrow him, so he swallowed up his children as soon as they were born. Rhea allowed Cronus to swallow a stone hidden in cloth that he thought was his latest newborn. Then she carried the baby Zeus to Mother Earth, who took him to Crete and hid him in the cave of Dicte on the Aegean Hill, although other stories say it was on Mount Ida. There the Goat-nymph Amalthea and the Ash-nymph Adrastea and her sister Io, both daughters of Melisseus, nursed him.
Amalthea was the Goat-nymph who nursed the infant Zeus with her goats milk on the Aegean Hill (or Mount Ida), where he was being hidden from Cronos, his father. His food was honey, and he shared the goats milk with Pan, his foster brother. Zeus was grateful for Am althea's kindness and set her image in the sky as Capricorn. Zeus also borrowed one of her horns and gave it to the sisters Adrastea and Io. It became the famous Cornucopia, or horn of plenty, which is always filled with whatever food or drink the owner may desire.
Thebe was a nymph and the daughter of the river god Asopus. She and her twin sister Aegina were both carried off and seduced by Zeus. Later she married Zethus, who rebuilt Cadmea. The name of that city was later changed to Thebes in her honor.
The Outer Moons
These four moons lie far out past Callisto and are much smaller than the large Galilean moons. Their orbits are close to one another, so they are considered to be a group that may be fragments of a destroyed moon or asteroid. Astronomers agreed that the names for this group of moons should all end in the letter a. Here are their stories:
Leda was the daughter of Thespia who married Tyndareus and became queen of Sparta. Zeus desired her and approached her disguised as a swan. After this encounter beside the river Eurotas, Leda laid an egg from which were hatched Helen (the famous Helen of Troy), Castor, Polydeuces (or Pollux), and Clytaemnestra. Some stories had only Helen and Polydeuces as the children of Zeus, with the other two offspring being fathered by Ledas husband Tyndareus.
Himalia was a nymph who bore three sons of Zeus. Very little is known about Himalias myth, just as little is actually known about this moon of Jupiter.
Lysithea was a daughter of Oceanus and one of Zeuss lovers. Not much more is known about the story of Lysithea or the moon Lysithea.
Elara and Zeus were the parents of Tityus the giant. Very little is known about the Elara myth or the moon Elara. What is told is that her son Tityus was caught trying to violate Apollos mother, Leto, at the sacred grove of Delphi, and for this Apollo and Artemis killed him. In Hades, Tityus was stretched out on nine acres of ground while two vultures ate his liver.
The Far Outer Moons
The last four of Jupiter's moons are quite small and are far from giant Jupiter. Curiously, all orbit in reverse direction (retrograde). These moons may also be fragments of a destroyed moon or asteroid, and by design all their names end in the letter 'e.' Here are their stories.
Ananke and Zeus were the parents of Adrastea, the distributor of rewards and punishments (not the same Adrastea that the inner moon is named after). Very little is known about Ananke, either myth or moon.
Carme was a nymph and attendant of Artemis. Carme and Zeus were the parents of Britomartis, a Cretan goddess. Little is known about Carmes myth or the moon named after her. Carmes daughter Britomartis was beloved of King Minos of Crete and was known to have invented hunting nets. Britomartis was also a companion of Artemis like her mother, and held the hunting goddesss hounds on a leash.
Pasiphae was a daughter of Helios and the nymph Crete (also called Perseis), and sister of Aeetes and Circe. She was married to King Minos of Crete and was the mother of Ariadne, Androgeus, Phaedra, and the Minotaur. When her husband neglected to sacrifice a beautiful white bull to Poseidon, that god made Pasiphae fall in love with the bull. She mated with it by disguising herself inside a hollow wooden cow made by the craftsman Daedalus. From this unnatural encounter she gave birth to the Minotaur, which had a bulls head and a mans body. Some stories claim it was Zeus who Minos offended instead of Poseidon. Pasiphaes husband Minos had many lovers just like Zeus, and she was a jealous wife very much like Hera.
Sinope was the river god Asopuss daughter. Zeus fell in love with her and promised her whatever gift she wished. Sinope craftily chose virginity, and made her home in Paphlagonia, where she spent the remainder of her life in happy solitude.
Last Updated: 16 February 2011