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JUPITER (MYTHOLOGY) In Roman mythology, Jupiter was the king of the gods and the lord of life and death. He was also called Jove. Jupiter was the son of SATURN and Rhea, the husband of JUNO, and the father of MINERVA. The Romans identified him with the Greek god ZEUS, but he retained to some degree his own distinctive character. Unlike Zeus, for example, he never came to visit humankind on earth. Jupiter was usually represented in art sitting on an ivory throne and holding a sheaf of thunderbolts. The eagle and the ox were sacred to him. His most celebrated temple was on the CAPITOLINE HILL in Rome.
Jupiter By Jove you were born: gigantic; red-eyed; swaddled in furious hurricanes; missing glory by fractions. Undone. Double sun majestically juggling all 16 captives in magical pirouettes of vengeance- spinning faint rings around your bloated body like an immense caterpillar doomed in its cocoon of beauty- awaiting the metamorphosis that will never come. carlyle miller


Jupiter and Io

Jupiter: Callisto

Jupiter: Europa

Jupiter: Galliean Moons

Jupiter: Ganymede

Jupiter: Io

Jupiter: Moons

Jupiter: Redspot

JUPITER (PLANET) Jupiter, the fifth planet from the Sun, is by far the most massive planet. Its mass represents more than two-thirds of the total mass of all the planets, or 318 times the mass of the Earth. If Jupiter had been several times more massive, it would have been a star, because the pressure and temperature at its center would have been great enough to set off nuclear fusion. Because Jupiter's density (1.3 g/cubic cm, or 82 lb/cubic ft) is relatively low, it has the volume of 1,317 Earths. Jupiter is 1,000 times smaller than the Sun; however, Jupiter's fast axial rotation--once every 9 hr 55.5 min--causes it to be considerably flattened: the equatorial diameter is 142,800 km (88,700 mi), but the distance from the north to south pole is only 133,500 km (83,000 mi). Jupiter orbits the Sun in 11.9 years at a distance of 778.3 million km (483.6 million mi), or 5.2 times the Earth's distance from the Sun. ORIGIN, STRUCTURE, COMPOSITION, AND WEATHER Jupiter may have formed, like the Sun, by gravitational collapse of part of the primeval solar nebula. Alternatively, if the nebula was less massive, dust particles that condensed as the nebula cooled would have coalesced due to collisions. Once Jupiter's "embryo" (now its rocky core, with a mass several times that of Earth's) became large enough, its gravity pulled together a surrounding envelope of gas from the nebula. Like the Sun and the primeval nebula, Jupiter is primarily composed of hydrogen and helium. The temperature is sufficiently warm that there is no solid surface under the atmosphere, only a gradual transition from gas to liquid. About one-fourth of the way into the planet, the pressure and temperature are so high that the liquid becomes metallic, by which physicists mean that the molecules are stripped of their outer electrons. Jupiter's atmosphere also contains trace amounts of water, ammonia, methane, and other organic (carbon) compounds. Astronomers theorize that three layers of clouds exist, separated by about 30 km (19 mi) in altitude. The lowest are made of water ice or droplets, the next are crystals of a compound of ammonia and hydrogen sulfide, and the highest are ammonia ice. Of the observed clouds, the blue ones are warmest and therefore at the lowest altitude. Browns, whites, and reds lie increasingly higher, in that order. These shades are believed to be caused by chemical disequilibrium, which allows sulfur, phosphorus, and organic compounds to color the clouds. This disequilibrium may be due to impact by charged particles, rapid vertical motion through changing temperature levels, or lightning. The two VOYAGER spacecraft that flew past Jupiter in 1979 observed lightning as well as AURORAS on Jupiter's night side. The winds on Jupiter move in jets parallel to the equator. The speeds--some eastward, some westward, and varying with latitude, or distance from the equator--are tens to a hundred meters per second relative to the rotating interior. The latitudes of the zonal jets correlate well with positions of broad, alternately colored bands of orange brown and whitish clouds seen by Earth-based telescopes. The differences in cloud coloration may be due to gas rising in some bands and descending in others. Weather on Jupiter is still not well understood. Eddies and storms form and dissipate, some lasting only a few days, others much longer. Some get caught between regions of different east-west wind speeds and are sheared apart. Larger eddies, such as long-lived white spots and the Earth-sized GREAT RED SPOT, are able to survive by rolling like ball bearings between zones. MAGNETIC FIELD Rotation and currents within the metallic hydrogen interior of Jupiter generate a magnetic field, much as the molten iron core of the Earth does. Jupiter's field is 4,000 times stronger than the Earth's. It is roughly dipolar, like a bar magnet, with its axis offset by 10,000 km (6,200 mi) from the center of the planet and tipped 11 degrees from Jupiter's rotation axis. As the planet spins, the magnetic field wobbles up and down with the electrically charged particles trapped within it. The result is a radio emission whose periodicity reveals the bulk rotation period of the planet. The plasma, or gas of charged particles, is locked to the magnetic field so that it rotates with it as well. This magnetosphere extends at least 20 Jovian radii away from the planet, forming an extremely large, intense radiation region in which some particles are accelerated to speeds of tens of thousands of kilometers per second. The satellite Io and, to a lesser degree, the other satellites sweep up the energetic electrons, which move roughly perpendicular to their orbits. Electric currents probably generated in Io may be responsible for long-puzzling radio bursts received on Earth from the direction of Jupiter. The energetic particles striking Io probably help remove atoms and ions of sodium, sulfur, and other elements from the satellite and put them into the doughnut-shaped cloud of these materials surrounding Jupiter along Io's orbit. Some of this material may also be ejected by volcanism on Io combined with the electromagnetic interaction with the magnetosphere. High-energy particles from the Io plasma torus spiral in along magnetic-field lines to Jupiter's atmosphere, where they stimulate the auroral-light emissions seen by the Voyager spacecraft. SATELLITES AND RINGS Although Jupiter was not large enough to begin nuclear burning, the compression of its own gravity generated a tremendous amount of heat when the planet formed. Even now, 4.6 billion years later, Jupiter radiates nearly twice as much heat as it receives from the Sun. Early on, when satellites were forming around Jupiter, heat radiating from the planet was much greater. Hence the satellites that formed are rockier near Jupiter and icier farther away. This trend is evident among the four large, Moon-sized satellites discovered by Galileo in 1610 and called the Galilean moons. The regular, circular, equatorial orbits of these satellites suggest that they did indeed form from a cloud of small particles circling Jupiter. The satellites, named CALLISTO, GANYMEDE, EUROPA, and IO, are described in separate entries. In addition to the Galilean moons, Jupiter has several smaller satellites and rings. Amalthea, the largest satellite interior to Io's orbit, is irregularly shaped, about 265 km (165 mi) long and 150 km (93 mi) wide. Its surface is dark and red and continually bombarded by the energetic particles of Jupiter's magnetosphere. Voyager 1 photographed (1979) a narrow ring orbiting the planet about halfway from the surface out to Amalthea. A fainter ring was found to extend from the bright ring right down to the planet; unlike the bright ring, it also extends away from the equatorial plane to form a cloud of particles surrounding the planet. Jupiter's rings are very diffuse. The ring particles must generally be about as big as the wavelength of light, that is, only a few microns. Particles this size are susceptible to electromagnetic effects that make them spiral down toward Jupiter. There is probably a population of boulder-size objects orbiting Jupiter that is bombarded by interplanetary micrometeoroids or perhaps by volcanic ejecta from Io. Debris from these boulders would continually resupply the rings with small particles. The bright ring may contain particles of a wide range of sizes, with two satellites found by the Voyager spacecraft near the ring's outer edge being the largest. Voyager also found another tiny satellite between the orbits of Amalthea and Io. The eight outer satellites of Jupiter are small, dark, stony objects that closely resemble the Trojan asteroids. This evidence, combined with their highly eccentric and inclined orbits near the limit of Jupiter's gravitational sphere of influence, suggests that the outer satellites were captured from interplanetary orbits. No satisfactory explanation has been offered for their clustering at two distinct distances from Jupiter or for the retrograde (opposite Jupiter's rotation) motion of the outer four satellites. Bibliography: Beebe, R. F., "Queen of the Giant Storms," Sky & Telescope, October 1990; Beatty, J. Kelly, et al., eds., The New Solar System (1981); Burgess, Eric, By Jupiter, Odysseys to a Giant (1982); Hughes, David, Jupiter (1989); Morrison, David, ed., Satellites of Jupiter (1983); Olivarez, Jose, "Jupiter's Best Show in Twelve Years," Astronomy, November 1987; Washburn, Mark, Distant Encounters: The Exploration of Jupiter and Saturn (1983). SATELLITES OF JUPITER --------------------------------------------------------------- Average Dist- ance from Center of Year of Jupiter Name Discoverer Discovery Km --------------------------------------------------------------- Metis Stephen Synnott 1980 128,000 Adrastea G.E. Danielson, 1979 128,700 D. Jewitt Amalthea Edward Barnard 1892 181,300 Thebe Stephen Synnott 1980 221,900 Io Galileo, Simon Mayr 1610 421,600 Europa Galileo, Simon Mayr 1610 670,900 Ganymede Galileo, Simon Mayr 1610 1,070,000 Callisto Galileo, Simon Mayr 1610 1,880,000 Leda Charles Kowal 1974 11,110,000 Himalia Charles Perrine 1904 11,470,000 Lysithea Seth Nicholson 1938 11,710,000 Elara Charles Perrine 1905 11,740,000 Ananke Seth Nicholson 1951 20,700,000 Carme Seth Nicholson 1938 22,350,000 Pasiphae P. J. Mellote 1908 23,300,000 Sinope Seth Nicholson 1914 23,700,000 Name Average Distance Period of Diameter From Center of Revolution Km Jupiter (days) Km Mi --------------------------------------------------------------- 1979 J3 79,500 0.295 40 Adrastea 80,000 0.297 24 Amalthea 112,700 0.489 260X150 1979 J2 137,900 0.675 80 Io 262,000 1.769 3,632 Europa 416,900 3.551 3,126 Ganymede 665,000 7.155 5,276 Callisto 1,168,000 16.689 4,820 Leda 6,904,000 240 20 Himalia 7,127,000 250.6 170 Lysithea 7,277,000 260 30 Elara 7,295,000 260.1 80 Ananke 12,850,000 617 30 Carme 13,900,000 692 40 Pasiphae 14,500,000 735 50 Sinope 14,750,000 758 40 Name Diameter Orbital Orbital Mi Inclination Eccentricity (degrees) --------------------------------------------------------------- Metis 25 ? ? Adrastea 15 ? ? Amalthea 162x93 0.455 0.003 Thebe 50 1.25 ? Io 2,256 0.027 0.004 Europa 1,942 0.468 0.01 Ganymede 3,278 0.183 0.001 Callisto 2,995 0.253 0.01 Leda 12 27 0.146 Himalia 105 28 0.158 Lysithea 19 29 0.130 Elara 50 25 0.207 Ananke 19 147 0.169 Carme 25 164 0,207 Pasiphae 31 145 0.40 Sinope 25 153 0.275 --------------------------------------------------------------- SOURCE: Adapted from table in J. Kelly Beatty, et al., eds., The New Solar System (Sky Publishing Corp. and Cambridge Univ. Press, (1981), p. 220.
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