JUPITER

Data from Wikipedia and NASA (C)

Jupiter is the fifth planet of the solar system in order of distance from the Sun, and is ther most massive. Its gravitational force plays a fundamental role in the determination of the orbits of other planets and smaller bodies (comets and asteroids) of the solar system; its mass is approximately 2.5 times the mass of all the other planets together. It is a gaseous giant: it does not possess a solid surface, but simply it is constituted of gas, that it becomes more and more dense towards the inside of the planet, until becoming liquid. Because of its nature and of the high speed of spin, its shape appears like a ellissoide, crushed to the poles.

History

Jupiter is famous since the antiquity, being visible to naked eye in the sky; the Roman gave the name of the God Jupiter. In 1610 Galileo Galilei discovered the four main satellites of the planet, called from then like galileian satellites, thanks to the telescope; they were the first celestial bodies to being characterizes in orbit around a planet from the Earth round. This element placed to favor of the copernicana theory. In the 1672 Rømer observing the satellites of Jupiter noticed that the times between the eclipses (in particular of Io) became short when the Earth was approached Jupiter and longer when the Earth went away. This strange effect was debt the speed of the light, determining some for the first time a precise value.

Observations from Earth

Jupiter is a planet particularly fascinating to observe with a telescope. It has visible atmospheric formations, like bands and zones, the first dark and second clear ones. With a deepened vision it is possible to see that they are not simply parallels between of they, but that they structures of vortices, like the Great Red Spot: a stable, great cyclone 2,5 times the Earth, than is moved longitudinally of approximately a meter to the second. Jupiter is an easy observable planet from Earth; it is very visible in the sky in the periods of osservability like a star of appearing magnitude -2,5, and it has an appearing diameter that it oscillates between the 44 and the 49 second ones of arc. Aiming the planet with binoculars of discreet dimensions it is already possible to discern the four galileian satellites, which have visible variations of position with passing of the hours. The vision with a telescope allows to observe numerous details of the jovian atmosphere. With the aid of instruments with diameter of 150 milimeter is possible to notice variations in the conformation of the bands with the vision of the waves; the atmosphere of the planet has other interesting details like the Great red spot and the WOS, true cyclones that cover the surface of the planet. Following a periodic study (leading that is a campaign of astronomical observation) is possible to find variation of the color and the brightness of the bands of Jupiter. Many of they stretch to disappear in order then to resume color after some years; also the Red Spot has extension color variations. The phenomena of the galileiani satellites are then spectacular, like the transits and the occultations. In their revolution around the planet, the satellites come periodically in fact hidden from the planetary disc or project their shadow. It is fascinating to observe the apparition or the disappearance of the satellites by the data contained in the ephemeres.

Orbital parameters

Jupiter orbit around the Sun to a medium distance of 778 412 020 km, correspondents to 5,20 astronomical units, with a perihelion of 740 762 600 km and an aphelion of 816 081 400 km; it completes one revolution in 11,8565 sidereal years, correspondent to 4332,667 days. The orbit of the planet is tilted of 1,305° regarding the ecliptic and 3,12° regarding its Equator, and is characterized from an orbital eccentricity equal to 0,04839. The mass of Jupiter is equal to 317,938 times that earthling; its volume is 1 408,377 times advanced; the equatorial radius corresponds to 11,209 earth radii; the medium density is 0,24 times that one of the Earth and the gravitational acceleration (to the top of clouds) is 2,34 times advanced.

Atmosphere

The jovian atmosphere, similarly to that one of Saturno, is made up for the maximum part of hydrogen and helium, the two same main elements that constitute the Sun and, in a generalized manner, the Universe. It is crossed from particularly violent winds, that they can catch up speed in the order of the 500-600 km/h. Jupiter rotates more quickly than all the other planets of Solar Sistema. Observing incedere of the spots on its surface, it is uncovered that the planet not rotates just as a solid body. However, to difference of the differentiates rotation of the Sun, that has a graduates variation of the speed from the Equator to the poles, the period of rotation of Jupiter has variations that remember those of the earth’s atmosphere. In wrap comprised between ±10° from the Equator, the period of rotation is of approximately 9h 50m. The atmosphere of Jupiter is constituted for 90% from hydrogen and 10% of helium, with several traces of methane and ammonia. The superior part of the atmosphere (thick 1000 kilometers) is moved from strongest winds that have a speed to the 400 and, occasionally, to the 500 hour kilometers. The clouds are forced from the high speed of rotation to form bands parallels to the Equator, interrupted from cyclonic perturbations. The greater one, call Great Red Spot, is an immense permanent vortex (with a diameter of 25-50000 kilometers, two times the Earth) that rotates together to the atmosphere. It came observed for the first time from the Italian astronomer Giovanni Cassini than 300 years ago. The spectroscopic analysis in the field in the infrared has allowed to characterize some components of the atmosphere of Jupiter who could denounce the presence of complex chemistries reactions still disowned in the low atmosphere. They are traces of carbon monoxide, fosfina, idruro of germanium and arsine. It thinks that these compounds, than normally could not exist in an atmosphere made up of hydrogen and helium, has origin approximately 400 km under the observable atmospheric level and are then pushes more up from strong convettivi motions. The planet is ideally divided in bands and zones; first they are dark cloudy structures, while the second ones are clear. They above all distinguish for the motions and the different temperatures: in the bands the temperatures more are elevated and the gases have a motion descendant towards the low layers of the atmosphere, while the zones introduce lower temperatures with an upward motion of the fluid. The visible atmosphere of Jupiter is moreover divided in equatorial, moderated zones and polar zone. With a telescope it is possible to notice visible structures dictated from the motion of the fluid, which of the extensions of the equatorial bands to arc shape, of the clear ovals (cyclones in motion) and the Great Red Spot.

Inner structure

Under the atmosphere the hydrogen, from gaseous, makes liquid, while to approximately 24000 kilometers of depth it is transformed in liquid metallic hydrogen; this much particular state is similar to that one caught up to the inside of the Sun, but to a temperature much inferior. One thinks that it is responsible of the enormous magnetic field of Jupiter. The subdivision between the various states is not precise, and the various phases of the hydrogen mixed one in the other gradually. The nucleus of the planet is small and full of rocks. The gravity on Jupiter, on its liquid surface, is much high one, the greater one in the solar system, excluded naturally the Sun. It has been estimated that that present is equal to 2,64 times on the Earth. The inside of Jupiter is dominated from a nucleus that has a diameter of 12 000 km, composed with much probability from silicati of iron subordinates to a temperature of 30 000°C, while in the transition zone the heat comes down to 11 000°C. Around the nucleus there is a metallic core of hydrogen and helium that because of the fast spin of the planet generates a great magnetic field that is 10 times advanced to that earthling, moreover it is subordinate to a pressure of 3 million atmospheres and in this mixture of proton to which they come tears electrons produces to running forts electrical workers. Over this it is a ocean of liquid molecular hydrogen, helium and other elements, and the obscurity is ripped from lightnings that come from the overhanging clouds which ramble above one water fog and ammonia.

Natural satellites

Jupiter is encircled from a series of thinnest rings composed from small particles full of rocks. Around the planet rotates 63 satellites, of which only 16 have a name. The more important, sayings also Galileiani or Medicei, were discoveries from Galileo Galilei and from this dedicates to Cosimo II de' Medici, and is:

Io: characterized from an intense volcanic activity, provoked from the small distance that separates it from Jupiter and its eccentric orbit. The satellite is in continuous mutation provoked from the emission of volcanic material.

Europe: it has a nucleos of rocks covered from a thick layer of ice, deprives of craters. It is the only body of Solar Sistema, beyond to the Earth, on which it is possible to find water in liquid shape, hidden under often the superficial ice layer. Because of the continuous movements of the crust ghiacciata on the surface of the satellite it is impossible to recover meteoritici craters, very visible on all the other jovian satellites.

Ganymed: the largest of the satellites, formed from ice and cliffs.

Callisto: composed from ice and cliff, has a surface intensely craterized.

The precise number of satellites never will not be quantified exactly, because the iced fragments that compose its rings can technically be consider such, and today the International Astronomical Union does not have to place with precision a line of distinction between smaller satellites and great iced fragments. The first four jovian satellites to being discoveries were the galileian, or medicei, than Galileo Galilei saw for the first time in 1610, although some assume one previous discovery from part of Chinese astronomer Gan De, in the 362 a.C.. In the three centuries comprised between the discovery of Galileo and the beginning of the spaces Time came progressively characterizes nine other satellites, thanks to the observation from Earth. The mission Voyager 1, in 1979, allowed the discovery other three inner satellites, carrying the total to 16; in truth it had been observed a seventeenth satellite, Temisto, but its orbital parameters could not be gain and its discovery did not come made official. Until the 1999 one thought therefore that the system of Jupiter was composed alone 16 satellites. Since the last new biennium of the XX century observations from Earth, lead through more and more powerful instruments, has allowed to the progressive location of new 46 satellites (beyond to the reaffirmation of Temisto), with the dimensions comprised between 3 and 9 km; it draft of asteroids or cometary fragmented bodies. The number of known jovian satellites is therefore reached 63. It follows a prospect with the data of the 63 known satellites of Jupiter, ordered for period of revolution around to the planet.

Name		Diameter	Weight	Orbital radius	Orbital Period	Discovery	Team
Jupiter XVI	Metide	43 km	120×10¹⁵ kg	127 690 km	0,294780 days	1979	Amaltea
Jupiter XV	Adrastea	26×20×16 km	7,5×10¹⁵ kg	128 694 km	0,29826 days	1979	Amaltea
Jupiter V	Amaltea	262×146×134 km	2,1×10¹⁸ kg	181 170 km	0,498179 days	1892	Amaltea
Jupiter XIV	Tebe	110×90 km	1,5×10¹⁸ kg	221 700 km	0,6745 days	1979	Amaltea
Jupiter I	Io	3 643 km	89×10²¹ kg	421 700 km	1,769138 days	1610	Galileian satellites
Jupiter II	Europa	3 122 km	48×10²¹ kg	671 034 km	3,551181 days	1610	Galileian satellites
Jupiter III	Ganimede	5 262 km	150×10²¹ kg	1 070 412 km	7,154553 days	1610	Galileian satellites
Jupiter IV	Callisto	4 821 km	110×10²¹ kg	1 882 709 km	16,689018 days	1610	Galileian satellites
Jupiter XVIII	Temisto	8 km	0,69×10¹⁵ kg	7 391 645 km	129,8276 days	1975
Jupiter XIII	Leda	20 km	11×10¹⁵ kg	11 097 245 km	238,8242 days	1974	Imalia
Jupiter VI	Imalia	170 km	6,7×10¹⁸ kg	11 432 435 km	249,7263 days	1904	Imalia
Jupiter X	Lisitea	36 km	63×10¹⁵ kg	11 653 225 km	256,9954 days	1938	Imalia
Jupiter VII	Elara	86 km	870×10¹⁵ kg	11 683 115 km	257,9849 days	1905	Imalia
S/2000 J 11		4 km	90×10¹² kg	12 570 575 km	287,9310 days	2000	Imalia
Jupiter XLVI	Carpo	3 km	45×10¹² kg	17 144 875 km	1,2556 anni	2003
S/2003 J 12		1 km	1,5×10¹² kg	17 739 540 km	1,3215 anni	2000
Jupiter XXXIV	Euporia	2 km	15×10¹² kg	19 088 435 km	1,4751 anni	2001	Ananke?
S/2003 J 3		2 km	15×10¹² kg	19 621 780 km	1,5374 anni	2003	Ananke
S/2003 J 18		2 km	15×10¹² kg	19 812 575 km	1,5598 anni	2003	Ananke
Jupiter XLII	Telsinoe	2 km	15×10¹² kg	20 453 755 km	1,6362 anni	2003	Ananke
Jupiter XXXIII	Euante	3 km	45×10¹² kg	20 464 855 km	1,6375 anni	2001	Ananke
Jupiter XLV	Elice	4 km	90×10¹² kg	20 540 265 km	1,6465 anni	2003	Ananke?
Jupiter XXXV	Ortosia	2 km	15×10¹² kg	20 567 970 km	1,6499 anni	2001	Ananke?
Jupiter XXIV	Giocasta	5 km	190×10¹² kg	20 722 565 km	1,6685 anni	2000	Ananke
S/2003 J 16		2 km	15×10¹² kg	20 743 780 km	1,6711 anni	2003	Ananke
Jupiter XII	Ananke	28 km	30×10¹⁵ kg	20 815 225 km	1,6797 anni	1951	Ananke
Jupiter XXVII	Prassidice	7 km	430×10¹² kg	20 823 950 km	1,6808 anni	2000	Ananke
Jupiter XXII	Arpalice	4 km	120×10¹² kg	21 063 815 km	1,7099 anni	2000	Ananke
Jupiter XXX	Ermippe	4 km	90×10¹² kg	21 182 085 km	1,7243 anni	2001	Ananke?
Jupiter XXIX	Tione	4 km	90×10¹² kg	21 405 570 km	1,7517 anni	2001	Ananke
Jupiter XL	Mneme	2 km	15×10¹² kg	21 427 110 km	1,7543 anni	2003	Ananke
S/2003 J 17		2 km	15×10¹² kg	22 134 305 km	1,8419 anni	2003	Carme
Jupiter XXXI	Aitne	3 km	45×10¹² kg	22 285 160 km	1,8608 anni	2001	Carme
Jupiter XXXVII	Cale	2 km	15×10¹² kg	22 409 210 km	1,8763 anni	2001	Carme
Jupiter XX	Taigete	5 km	160×10¹² kg	22 438 650 km	1,8800 anni	2000	Carme
S/2003 J 19		2 km	15×10¹² kg	22 709 060 km	1,9141 anni	2003	Carme
Jupiter XXI	Caldene	4 km	75×10¹² kg	22 713 445 km	1,9147 anni	2000	Carme
S/2003 J 15		2 km	15×10¹² kg	22 721 000 km	1,9156 anni	2003	Ananke?
S/2003 J 10		2 km	15×10¹² kg	22 730 815 km	1,9168 anni	2003	Carme?
S/2003 J 23		2 km	15×10¹² kg	22 739 655 km	1,9180 anni	2003	Pasifae
Jupiter XXV	Erinome	3 km	45×10¹² kg	22 986 265 km	1,9493 anni	2000	Carme
Jupiter XLI	Aede	4 km	90×10¹² kg	23 044 175 km	1,9566 anni	2003	Pasifae
Jupiter XLIV	Callicore	2 km	15×10¹² kg	23 111 825 km	1,9652 anni	2003	Carme?
Jupiter XXIII	Calice	5 km	190×10¹² kg	23 180 775 km	1,9740 anni	2000	Carme
Jupiter XXXII	Euridome	3 km	45×10¹² kg	23 230 860 km	1,9804 anni	2001	Pasifae?
Core		2 km	15×10¹² kg	23 238 595 km	1,9814 anni	2003	Pasifae
Jupiter XXXVIII	Pasitea	2 km	15×10¹² kg	23 307 320 km	1,9902 anni	2001	Carme
Jupiter XLVIII	Cillene	2 km	15×10¹² kg	23 396 270 km	2,0016 anni	2003	Pasifae
Jupiter XLVII	Eucelade	4 km	90×10¹² kg	23 483 695 km	2,0129 anni	2003	Carme
S/2003 J 4		2 km	15×10¹² kg	23 570 790 km	2,0241 anni	2003	Pasifae
Jupiter XXXIX	Egemone	3 km	45×10¹² kg	23 702 510 km	2,0411 anni	2003	Pasifae
Jupiter XLIII	Arche	3 km	45×10¹² kg	23 717 050 km	2,0429 anni	2002	Carme
Jupiter XI	Carme	46 km	0,13×10¹⁸ kg	23 734 465 km	2,0452 anni	1938	Carme
Jupiter XXVI	Isonoe	4 km	75×10¹² kg	23 832 630 km	2,0579 anni	2000	Carme
S/2003 J 9		1 km	1,5×10¹² kg	23 857 810 km	2,0612 anni	2003	Carme
S/2003 J 5		4 km	90×10¹² kg	23 973 925 km	2,0762 anni	2003	Carme
Jupiter VIII	Pasife	60 km	300×10¹⁵ kg	24 094 770 km	2,0919 anni	1908	Pasifae
Jupiter IX	Sinope	38 km	75×10¹⁵ kg	24 214 390 km	2,1075 anni	1908	Pasifae
Jupiter XXXVI	Sponde	2 km	15×10¹² kg	24 252 625 km	2,1125 anni	2001	Pasifae
Jupiter XXVIII	Autonoe	4 km	90×10¹² kg	24 264 445 km	2,1141 anni	2001	Pasifae
Jupiter XVII	Calliroe	9 km	870×10¹² kg	24 356 030 km	2,1261 anni	1999	Pasifae
Jupiter XIX	Megaclite	5 km	210×10¹² kg	24 687 240 km	2,1696 anni	2000	Pasifae
S/2003 J 2		2 km	15×10¹² kg	30 290 845 km	2,9487 anni	2003

Although the distinction is not defined rigorously, the satellites of Jupiter can be classify to you as it follows.

Inner satellites

The group of Amaltea and those galileian satellites are made up of homogenous satellites between they for physical and orbital parameters.

External satellites

The numerous remaining bodies, generally OF contained dimensions, can be group to you in three families, that carry the name of the main satellite and share relatively similar parameters or orbital characteristics. The satellites of the group of Carme have orbits characterized from a major semiaxle of 23 404 000 km, an equal orbital inclination to 165,2±0,3° and an eccentricity comprised between 0,238 and 0,272. Only S/2003 J 10 hasn’t partially these parameters, because of the elevated eccentricity of its orbit. The satellites of the group of Ananke orbit to a medium distance from Jupiter to 21 276 000 km, with equal inclinations to 149,0±0,5° and eccentricity comprised between 0,216 and 0,244; however only the eight main members (S/2003 J 16, Mneme, Euante, Ortosia, Arpalice, Prassidice, Tione, Telsinoe, Ananke and Giocasta) respect all the parameters, while remaining partially the eight bodies are various. The group of Pasife groups the remaining satellites; it is centered on a major semiaxle of 23 624 000 km, the orbital inclinations are in the order of the 151,4±6,9° and the eccentricities are comprised between 0,156 and 0,432. It could be a matter of an ancient group of satellites in phase of progressive disintegration, or of a simple grouping of bodies lacking in a common origin.

Exploration of Jupiter

Many spatial missions have carried probes in vicinity of Jupiter. Pioneer 10 has made a flyby of Jupiter in the month of December of 1973, then Pioneer 11 exactly a year later. They have been the first probes to fly over the gaseous planet, photographing for he first time the surface. Voyager 1 has carried out a flyby in March of the 1979 continuation from Voyager 2 in the July of the same year. The Voyager missions have improved enormously the understanding of the galileiani moons and to the discovery of rings of Jupiter. Also they have resumed the first near images of the atmosphere of the planet. In the February of 1992, the solar probe Ulysses has carried out a fly-by around Jupiter to one distance of 450 000 km (6,3 jovian radii. The flyby it was necessary in order to catch up the polar orbit around the Sun, and is taken advantage of in order to lead studies on the magnetosfera of Jupiter. Since the probe did not have television cameras, has not been any image. In February 2004 the probe was approached Jupiter newly, even if this time the distance was much greater one, approximately 240 million kilometers. Reached on Jupiter in 1995, the Galileo probe has executed measures and photographies around the planet until to 2003 with the crash in atmosphere. In 2000 the probe Cassini, in travel towards Saturn, it flies over Jupiter, transmitting to earth some of the higher definition images of the planet. Thanks to the performances of the radiometric modality of the radar, happen for the first time the measure in Ku band of the radiations of sincrotrone around the planet. The probe New Horizons has have a assist gravitational flying over Jupiter on 28 February 2007 in order to obtain the speed necessary in order to catch up the farthest Pluto in 2015. The New Horizons has been the first small probe launched directly towards Jupiter after the Ulysses. The instruments of the probe have begun to resume images and to collect data of the jovian system September 2006. It has transmitted to earth spectacular images of the jovian system, in particular of the galileiani satellites, sending data that they have allowed to obtain with greater precision the orbital parameters of some satellites. NASA is planning a mission for the study of Jupiter from a polar orbit. The launch of the Juno mission is programmed for 2011. Because of the possibility of a liquid ocean on one of the moons of Jupiter, Europe, has been a great interest to study the iced moon. A mission proposed from NASA was dedicated to their study. The launch of mission JIMO (Jupiter Icy Moons Orbiter) was attended for 2012. However, the mission has been considered too much ambitious and its financing has been cancelled.