The results of Jupiter's research below are obtained both from ground-based astronomy and from the very successful missions of the American Pioner-10 (1973) and Pioneer-11 (1974), "Voyager-1 and -2 (1979), Ulysses (1992), Cassini (2000), New Horizons (2007) and, to a large extent, Galileo (1995-2003), which was the first artificial satellite of Jupiter and for the first time dropped into the atmosphere of this
Saturn was nearly as completely explored: Pioneer eleven (1979), traveler one (1980) and traveler two (1971) came about close to him, and in 2004 his orbiter was Cassini, that ought to operate till a minimum of 2008. the remainder of the enormous planets haven't nonetheless been explored in such detail, as just one fly-by expedition has been carried out: traveler two has become nearer to Uranus (1986) and Neptune (1989). of these expeditions were organized by National Aeronautics and Space Administration, and solely the ECU house Agency (ESA) and also the Italian house Agency (ISA) took half within the preparation of Cassini.
Main planet
Jupiter leads the family of large planets, together with Saturn, Uranus, and Neptune. This cluster occupies the outer a part of our planet system, that conjointly homes the orbit of Pluto. however by its terrible nature, Pluto is nearer to major large planetary satellites. However, considering that Pluto moves round the Sun on its own and has its own satellites, in 2006, the International Astronomical Union (IAU) approved it as a paradigm for a replacement category of scheme objects referred to as "dwarf planets. Therefore, currently, the entire family of classic planets is clearly divided into 2 groups: planets of the planet kind ar set within the inner a part of our planet system, and large planets, ranging from Jupiter, along with their satellites occupy the outer a part of the system.
The group of giant planets is characterized by a low average density: from 0.70 g/cm³ of Neptune. This is significantly less than the average density of the Earth (5.52 g/cm³) and other planets of the Earth's group. Nevertheless, the size of giants is so large that they account for 99.5% of the total mass of the planetary system, or 445 masses of the Earth. Jupiter has the largest mass: 318 masses of the Earth, or 1/1047 masses of the Sun. Practically all kinetic energy of rotation of planets (both daily and orbital), and also all moment of an impulse of planetary system falls on planets-giants. Moreover, the orbital momentum of the Jupiter alone significantly exceeds the entire moment of the Sun's own momentum, so that almost the entire moment of rotation of the solar system is contained in the giant planets. (However, the kinetic energy of rotation is still concentrated in the Sun).
The low average density of the biggest of the giants indicates a little molecular mass of the most elements, which might be solely light-weight element and He. it's these gases that structure the atmospheres of Jupiter and Saturn. Probably, these same parts principally fill their bowels. the upper average density of Uranus and Neptune implies that additionally to element and He, they conjointly contain heavier parts.
Relationship to the sun
Despite their huge size, the giant planets get relatively little heat from the Sun. The reason is their remoteness from the Sun and rather high albedo (about 0.5). Even Jupiter absorbs only 2.2 times more solar energy than the Earth; the other giants are ten times less. Therefore, all giant planets have a flow of internal heat comparable to the flow of absorbed solar energy (and some even exceed it).
The composition, structure, low average density and rapid rotation of Jupiter are typical for other giants. But the peculiarity of Jupiter is its low inclination of the equator to the orbit, only 3˚. Together with the low eccentricity of the orbit, this results in almost no change of season.
Jupiter is a convenient object of astronomical observations. Its confrontations are repeated every 399 days. The size of Jupiter is great: from 11.2 times the diameter of the Earth, 1320 times the volume and 318 times the mass. Gravity at the planet's equator is 2.36 times greater than that of the Earth. At poles, it is even more on 16 %. Thanks to the huge mass of Jupiter, the values of the first and second space velocities at an altitude of 1000 km from the upper boundary of the clouds are 42 and 59 km/s, respectively. The period of satellite circulation in such a circular orbit will be only 3 hours, despite the very long distance from the center of the planet (72 400 km). However, since a satellite could not travel closer to the planet, this was the minimum orbital period around Jupiter, whereas around the Earth it was possible to travel in just 1.5 hours. The huge significance of the second space velocity makes it extremely difficult to create a descent to Jupiter.
With a huge equatorial radius (71,400 km), Jupiter turns around the axis in just 9 hours and 55.5 minutes. The equatorial points move at a speed of 12.6 km/s. Centrifugal force visibly deforms Jupiter: its polar diameter is 7% smaller than the equatorial one. Back in the 17th century it became known that Jupiter does not rotate like a solid body: its equatorial zone makes a revolution faster than other zones. That's why two coordinate systems were previously used to identify the details on Jupiter's disk: "System I" with a daily period of 9 h 50 min 30.003 s is used for the equatorial zone up to ±(10-15)˚, and at higher latitudes "System II" with a daily period of 9 h 55 min 40.632 s is used. Of course. These are only the average rotation periods of these areas; within each of them, the angular velocity varies slightly along the latitude and is quite intricate. Recently "system III" is considered to be preferable, connected with rotation of a magnetic field of a planet, having the period of 9 h 55 min 30 sec.
What is there?
All visible surfaces of Jupiter and details on that the periods of rotation square measure outlined square measure dense enough clouds. They type varied stripes of amber, white, red and blue-black shades. The stripes covering the earth, as parallels, type systems of dark belts and light-weight zones, comparatively symmetrically set to the north and south of the equator. though the belts and zones square measure permanent formations on Jupiter, their look is kind of variable. the final hue of Jupiter additionally changes. The patterned structure of bad weather covers the equatorial a part of the earth and reaches latitudes of ±40˚. North and south of the clouds type a field with brown and blue-black spots, apparently circular in character, up to 1,000 klick in diameter.