UCL: Cassini reveals oxygen atmosphere of Saturn’s moon Rhea

[bystander]

Cassini reveals oxygen atmosphere of Saturn’s moon Rhea
University College London | 26 Nov 2010

Rhea Encounter 26 Nov 2005 [i](Credit: UCL/Science/AAAS)[/i]

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A fragile atmosphere infused with oxygen and carbon-dioxide has been discovered at Saturn's moon Rhea by the Cassini-Huygens mission - the first time a spacecraft has captured direct evidence of an oxygen atmosphere at a world other than Earth.

The NASA-led international mission made the discovery using combined data from Cassini’s instruments, which includes a sensor designed and built at UCL’s (University College London) Mullard Space Science Laboratory.

Published today in Science Express, results from the mission reveal that the atmosphere of Rhea, Saturn’s second largest moon at 1500 km wide, is extremely thin and is sustained by high energy particles bombarding its icy surface and kicking up atoms, molecules and ions into the atmosphere.

The density of oxygen is probably about 5 trillion times less dense than in Earth’s atmosphere. However, the formation of oxygen and carbon dioxide could possibly drive complex chemistry on the surfaces of many icy bodies in the universe.

"The new results suggest that active, complex chemistry involving oxygen may be quite common throughout the solar system and even our universe," said Dr Ben Teolis, a Cassini team scientist based at Southwest Research Institute in San Antonio and lead author. "Such chemistry could be a pre-requisite for life. All evidence from Cassini indicates Rhea is too cold and devoid of the liquid water necessary for life as we know it."

Cassini Finds Ethereal Atmosphere at Rhea
NASA JPL Cassini | 2010-399 | 26 Nov 2010

[url=http://www.nasa.gov/mission_pages/cassini/multimedia/pia12648.html]Well Lit Rhea[/url] [i](Credit: NASA/JPL/SSI)[/i]

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NASA's Cassini spacecraft has detected a very tenuous atmosphere known as an exosphere, infused with oxygen and carbon dioxide around Saturn's icy moon Rhea. This is the first time a spacecraft has directly captured molecules of an oxygen atmosphere – albeit a very thin one -- at a world other than Earth.

The oxygen appears to arise when Saturn's magnetic field rotates over Rhea. Energetic particles trapped in the planet's magnetic field pepper the moon’s water-ice surface. They cause chemical reactions that decompose the surface and release oxygen. The source of the carbon dioxide is less certain.

Oxygen at Rhea's surface is estimated to be about 5 trillion times less dense than what we have at Earth. But the new results show that surface decomposition could contribute abundant molecules of oxygen, leading to surface densities roughly 100 times greater than the exospheres of either Earth's moon or Mercury. The formation of oxygen and carbon dioxide could possibly drive complex chemistry on the surfaces of many icy bodies in the universe.

Cassini Finds an Oxygen–Carbon Dioxide Atmosphere at Saturn’s Icy Moon Rhea - BD Teolis et al

• Science Express (online 25 Nov 2010) DOI: 10.1126/science.1198366

Saturn Moon Rhea's Surprise: Oxygen-Rich Atmosphere
Space.com | Science News | 25 Nov 2010

Saturn Moon Has Oxygen Atmosphere
National Geographic | Daily News | 25 Nov 2010

Cassini finds oxygen-carbon dioxide atmosphere on Saturn's moon Rhea
PhysOrg | Space Exploration | 26 Nov 2010

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[color=#0000FF][b]Rheo sat: Rhea is usually depicted seated on a throne flanked by (electrical) lions.[/b][/color]

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<<Rhea was the Titaness daughter of Uranus, the sky, and Gaia, the earth, in Greek mythology. She was known as "the mother of gods." Plato connected her name with "ῥέω" (reo), "flow", "discharge." [Rheostat, n. ("ῥέω" + standing still.) A contrivance for adjusting or regulating the strength of electrical currents.] The second largest moon of the planet Saturn is named after her. In earlier traditions, she was strongly associated with Gaia and Cybele, the Great Goddess, and was later seen by the classical Greeks as the mother of the Olympian gods and goddesses. The Romans identified Rhea with the Goddess Ops. The original seat of her worship was in Crete.

Cronus, Rhea's Titan brother and husband, castrated their father, Uranus and he and Rhea took the throne as King and Queen of the gods. Cronus sired six children by Rhea: Hestia, Hades, Demeter, Poseidon, Hera and Zeus in that order, but swallowed them all as soon as they were born, since he had learned from Gaia and Uranus that he was destined to be overcome by his own child as he had overthrown his own father. However, Rhea sought Uranus and Gaia to devise a plan to save him, so that Cronus would get his retribution for his acts against Uranus and his own children. Rhea gave birth to Zeus in Crete, handing Cronus a stone wrapped in swaddling clothes, which he promptly swallowed. Then she hid Zeus in a cave on Mount Ida in Crete. The nymphs Ida & Adrastea were charged by Rhea with nurturing the infant Zeus in the Dictaean cave using milk from the goat Amalthea. The Curetes kept Cronus from hearing Zeus cry by beating their swords on their shields. Adrastea (Greek for "inescapable") gave the infant Zeus a beautiful globe (sphaira) to play with, and on some Cretan coins Zeus is represented sitting upon a globe. The ball, which Aphrodite promises to Eros, is described as if it were the Cosmos: "its zones are golden, and two circular joins curve around each of them; the seams are concealed, as a twisting dark blue pattern plays over them. If you throw it up with your hands, it sends a flaming furrow through the sky like a star."

Zeus forced Cronus to disgorge the other children in the reverse order in which they had been swallowed, the oldest becoming the last, and youngest: first the stone, which was set down at Pytho under the glens of Parnassus to be a sign to mortal men, then the rest. In some versions, Metis gave Cronus an emetic to force him to disgorge the babies, or Zeus cut Cronus' stomach open. Then Zeus released the brothers of Cronus, the Gigantes, the Hecatonkheires and the Cyclops, who gave him thunder and lightning, which had previously been hidden by Gaia. Zeus and his siblings, together with the Gigantes, Hecatonkheires, and Cyclopes, overthrew Cronus and the other Titans.

Similarly, in later myths, Zeus would swallow Metis (Μῆτις, "wisdom," "skill," or "craft") to prevent the birth of her child, Athena, but she was born unharmed, out of a wound made in his head by one of the other gods.

In historic times, the resemblances between Rhea and the Asiatic Great Mother, Phrygian Cybele, a manifestation of the Great Goddess, were so noticeable that the Greeks accounted for them by regarding the latter as their own Rhea, who had deserted her original home in Crete and fled to the mountain wilds of Asia Minor to escape the persecution of Cronus. In Homer, Rhea is the mother of the gods, though not a universal mother like Cybele, the Phrygian Great Mother, with whom she was later identified. In the Argonautica by Apollonius of Rhodes, the fusion of Rhea and Phrygian Cybele is complete. "Upon the Mother depend the winds, the ocean, the whole earth beneath the snowy seat of Olympus; whenever she leaves the mountains and climbs to the great vault of heaven, Zeus himself, the son of Cronus, makes way, and all the other immortal gods likewise make way for the dread goddess," the seer Mopsus tells Jason in Argonautica; Jason climbed to the sanctuary high on Mount Dindymon to offer sacrifice and libations to placate the goddess, so that the Argonauts might continue on their way. For her temenos they wrought an image of the goddess, a xoanon, from a vine-stump. There "they called upon the mother of Dindymon, mistress of all, the dweller in Phrygia, and with her Titias and Kyllenos who alone of the many Cretan Daktyls of Ida are called 'guiders of destiny' and 'those who sit beside the Idaean Mother'." They leapt and danced in their armour: "For this reason the Phrygians still worship Rhea with tambourines and drums".>>

[Ann]

Wow, what a picture, Art. Rhea looks like she is balancing a slightly egg-shaped Sun on her shoulder and holding a beggar's bowl in her hand. And that small lion with an almost human face, would that be her castrated and generally diminished husband Cronus?

Ann

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Wow, what a picture, Art. Rhea looks like she is balancing a slightly egg-shaped Sun on her shoulder and holding a beggar's bowl in her hand. And that small lion with an almost human face, would that be her castrated and generally diminished husband Cronus?

It was Cronus (i.e., Saturn), Rhea's Titan brother and husband, who castrated their father, Uranus.

Which X-planes why Saturn has that buzz saw set of rings
while Uranus is spinning all topsy-turvy.

Giorgio Vasari: The Mutilation of Uranus by Saturn (Cronus)

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<<While the Greeks considered Cronus a cruel and tempestuous force of chaos and disorder, believing the Olympian gods had brought an era of peace and order by seizing power from the crude and malicious Titans, the Romans took a more positive and innocuous view of the deity, by conflating their indigenous deity Saturn with Cronus. Consequently, while the Greeks considered Cronus merely an intermediary stage between Uranus and Zeus, he was a larger aspect of Roman religion. The Saturnalia [X-mas celebration] was a festival dedicated in his honor, and at least one temple to Saturn already existed in the archaic Roman Kingdom.

His association with the "Saturnian" Golden Age eventually caused him to become the god of "human time", i.e., calendars, seasons, and harvests — not to be confused with Chronos, the unrelated embodiment of time in general. As a result of Cronus' importance to the Romans, his Roman variant, Saturn, has had a large influence on Western culture. The seventh day of the Judaeo-Christian week is called in Latin Dies Saturni ("Day of Saturn"), which in turn was adapted and became the source of the English word Saturday. In astronomy, the planet Saturn is named after the Roman deity. It is the outermost of the Classical planets.>>

[Ann]

Right, I mixed them up, as I always do. I know the story of Uranus and Chronos, really. The goddess Venus was born out of the splash when Uranus's "male parts" fell into whatever sea they fell into. Hmmm. Imagine Venus, most feminine of all goddesses, being born out of... those.

And I guess that's why Uranus is so pale, too. Poor guy. No doubt his lack of a healthy cerulean face is due to his, well, incompleteness.

Ann

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I know the story of Uranus and Chronos, really. The goddess Venus was born out of the splash when Uranus's "male parts" fell into whatever sea they fell into. Hmmm. Imagine Venus, most feminine of all goddesses, being born out of... those.

And I guess that's why Uranus is so pale, too. Poor guy. No doubt his lack of a healthy cerulean face is due to his, well, incompleteness.

<<"Foam-arisen" Aphrodite was born of the sea foam near Paphos, Cyprus after Cronus severed Uranus' genitals and threw them behind him into the sea, while the Furies emerged from the drops of blood.>>

‘Mine is a long and a sad tale!’ said the Mouse, turning to Alice, and sighing.

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‘It is a long tail, certainly,’ said Alice, looking down with wonder at the Mouse’s tail; ‘but why do you call it sad?’ And she kept on puzzling about it while the Mouse was speaking, so that her idea of the tale was something like this:—

Code: Select all

     ‘Fury said to a
    mouse, That he
   met in the
  house,
 “Let us
  both go to
   law: I will
    prosecute
     you.—Come,
      I’ll take no
       denial; We
      must have a
     trial: For
    really this
     morning I’ve
      nothing
       to do.”
      Said the
     mouse to the
    cur, “Such
     a trial,
      dear Sir,
       With
        no jury
       or judge,
      would be
     wasting
    our
     breath.”
      “I’ll be
       judge, I’ll
        be jury,”
         Said
          cunning
           old Fury:
          “I’ll
           try the
            whole
             cause,
              and
             condemn
            you
           to
          death.”’

FW 331.35: For the joy of the dew on the flower of the fleets on the fields of the foam of the waves of the seas of the wild main from Borneholm has jest come to crown.

<<Aphrodite (Greek Ἀφροδίτη) is the Greek goddess of love, beauty, and sexuality. Her Roman equivalent is the goddess Venus. According to Hesiod's Theogony, she was born when Cronus cut off Uranus' genitals and threw them into the sea. According to this interpretation, the name is from aphros (ἀφρός) "foam" and deato "to shine", meaning "she who shines from the foam [ocean]", a byname of the dawn goddess (Eos). Mallory & Adams (1997) have also proposed an etymology based on the connection with the Indo-European dawn goddess, from *abhor- "very" and *dhei "to shine".

The Birth of Venus by Sandro Botticelli

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Hesiod's Theogony described that the genitals "were carried over the sea a long time, and white foam arose from the immortal flesh; with it a girl grew" to become Aphrodite. Aphrodite floated in on a scallop shell. When she arose, she was hailed as "Cyprian," and is referred to as such often, especially in the poetic works of Sappho. This myth of a fully mature Venus (the Roman name for Aphrodite), Venus Anadyomene ("Venus Rising From the Sea") was one of the iconic representations of Aphrodite, made famous in a much-admired painting by Apelles, now lost, but described in the Natural History of Pliny the Elder.

Thus Aphrodite is of an older generation than Zeus. Iliad (Book V) expresses another version of her origin, by which she was considered a daughter of Dione, who was the original oracular goddess ("Dione" being simply "the goddess, the feminine form of Δíος, "Dios," the genitive of Zeus) at Dodona. Aphrodite herself was sometimes referred to as "Dione." Once the worship of Zeus had usurped the oak-grove oracle at Dodona, some poets made him out to be the father of Aphrodite.

http://antwrp.gsfc.nasa.gov/apod/ap100420.html
http://antwrp.gsfc.nasa.gov/apod/ap070801.html
http://antwrp.gsfc.nasa.gov/apod/ap060905.html
http://antwrp.gsfc.nasa.gov/apod/ap051026.html

In Homer, Aphrodite, venturing into battle to protect her son, Aeneas, is wounded by Diomedes and returns to her mother, to sink down at her knee and be comforted. "Dione" seems to be an equivalent of Rhea, the Earth Mother, whom Homer has relocated to Olympus, and refers to a hypothesized original Proto-Indo-European pantheon, with the chief male god (Di-) represented by the sky and thunder, and the chief female god (feminine form of Di-) represented as the earth or fertile soil.

Aphrodite's chief center of worship remained at Paphos, on the south-western coast of Cyprus, where the goddess of desire had been worshipped from the early Iron Age as Ishtar and Ashtaroth. It was said that, as Kythereia, she first tentatively came ashore at Cythera, a stopping place for trade and culture between Crete and the Peloponesus. Thus perhaps we have hints of the track of Aphrodite's original cult from the Levant to mainland Greece.

The connection to Phoenician religion claimed by Herodotus I.105,131) has led to inconclusive attempts at deriving Greek Aphrodite from a Semitic Aštoret, via hypothetical Hittite transmission. Another Semitic etymology compares Assyrian barīrītu, the name of a female demon found in Middle Babylonian and Late Babylonian texts. The name probably means "she who (comes) at dusk," which would identify Aphrodite in her personification as the evening star, a significant parallel she shares with Mesopotamian Ishtar.>>