Jupiter, the fifth largest in the distance from the Sun and the largest planet in the Solar System, is 5.2 times farther from the Sun than the Earth, and spends almost 12 years in orbit. The equatorial diameter of Jupiter is 142,600 km (11 times the diameter of the Earth). The rotation period of Jupiter is the shortest of all the planets – 9h 50 min 30s at the equator and 9h 55min 40s in the middle latitudes. Thus, Jupiter, like the sun, does not rotate like a solid – the rotation speed is not the same at different latitudes. Due to the fast rotation, this planet has a strong compression at the poles. The mass of Jupiter is equal to 318 Earth masses. The average density is 1.33 g / cm3, which is close to the density of the Sun. The axis of rotation of Jupiter is almost perpendicular to the plane of its orbit (inclination 87 °). Even in a small telescope, the polar compression of Jupiter and the bands on its surface parallel to the equator of the planet are visible. The visible surface of Jupiter is the upper level of the clouds surrounding the planet. Due to this, all the details on the surface of Jupiter are constantly changing their appearance. Of the stable details, the Great Red Spot has been known for over 300 years. This is a huge oval formation, measuring about 35,000 km in longitude and 14,000 in latitude between the southern tropical and southern temperate bands. Its color is reddish, but subject to change.
Spectral studies of Jupiter showed that its atmosphere consists of molecular hydrogen and its compounds: methane and ammonia. Ethane, acetylene, phosphene and water vapor are also present in small amounts. The clouds of Jupiter are composed of crystals and droplets of ammonia. In December 1973, with the help of the American spacecraft Pioneer 10, it was possible to detect the presence of helium in the atmosphere of Jupiter and measure its content. We can assume that the atmosphere of Jupiter is 74% hydrogen and 26% helium. Methane accounts for no more than 0.1% of the composition of the planet’s atmosphere (by weight). The atmospheric layer has a thickness of about 1000 km. Below the purely gas layer in the atmosphere lies a layer of clouds, which we see through a telescope. The layer of liquid molecular hydrogen has a thickness of 24,000 km. At this depth, the pressure reaches 300 GPa and the temperature is 11,000 K; here, hydrogen passes into a liquid metallic state, i.e. becomes like liquid metal. The layer of liquid metallic hydrogen has a thickness of about 42,000 km. Inside it is a small iron-silicate solid core with a radius of 4,000 km. The temperature at the boundary of the nucleus reaches 30,000 K. In 1956, Jupiter radio emission was detected at a wavelength of 3 cm, corresponding to thermal radiation with a temperature of 145 K. According to measurements in the infrared range, the temperature of the outermost clouds of Jupiter is 130 K. Flights of American spacecraft Pioneer -10 “and” Pioneer-11 “made it possible to clarify the structure of the magnetosphere of Jupiter, and a change in the temperature of the cloud layer basically confirmed the result known from ground-based observations: the amount of heat that Jupiter emits is more than two times thermal energy that the planet receives from the sun. It is possible that heat coming from the bowels of the planet is released in the process of slow compression of a giant planet (1 mm per year).
The planet’s magnetic field turned out to be complex and consists of two fields: a dipole (like the Earth’s field), which extends up to 1.5 million km from Jupiter, and a non-dipole, occupying the rest of the magnetosphere. The magnetic field near the surface is 20 times greater than on Earth. In addition to thermal and decimetric radio emission, Jupiter is a source of radio bursts (sharp amplifications of radiation power) at waves from 4 to 85 m long, lasting from fractions of a second to several minutes or even hours. However, long-term disturbances are not separate bursts, but a series of bursts – peculiar noise storms and thunderstorms. According to modern hypotheses, these bursts are explained by plasma oscillations in the planet’s ionosphere.
Jupiter has 13 satellites. The first 4 satellites were discovered by Galileo (Io, Europe, Ganymede, Callisto). They, as well as the inner, closest satellite of Amalthea, move almost in the plane of the equator of the planet. Io and Europe are almost comparable to the Moon, and Ganymede and Callisto are even larger than Mercury, although they are much inferior in mass to it. Compared to other satellites, the Galilean ones were studied in more detail. External satellites revolve around the planet in strongly elongated orbits with large angles of inclination to the equator (up to 30 °). These are small bodies – from 10 to 120 km, apparently of irregular shape. The outermost 4 moons of Jupiter revolve around the planet in the opposite direction. According to data obtained from the American Voyager spacecraft, Jupiter is surrounded in the equatorial region by a ring system. The ring is located at a distance of 50,000 km from the surface of the planet, its width is about 1,000 km. The existence of the Jupiter ring was predicted in 1960 by the astronomer S.K. Vsekhsvyatsky based on observations. In 1975, an object was discovered, which, apparently, is the 14th satellite of Jupiter. Its orbit is unknown.