Solar System: Composition and Features
The Sun enters the Solar System, 9 large planets together with their 34 satellites, more than 100 thousand small planets (asteroids), about 10 to the 11th degree of comets, and also countless small, so-called meteor bodies (from 100 meters across to negligible dust particles ) The central position in the solar system is occupied by the sun. Its mass is approximately 750 times greater than the mass of all other bodies included in the system. The gravitational attraction of the sun is the main force that determines the movement of all the bodies of the solar system that revolve around it. The average distance from the Sun to the planet farthest from it is Pluto 39.5 AU, i.e. 6 billion kilometers, which is very small compared with the distances to the nearest stars. Only some comets are 100 thousand AU away from the Sun. and are exposed to the attraction of stars. Moving in the galaxy, the solar system from time to time flies through interstellar dust clouds. Due to the extreme discharged matter of these clouds, the immersion of the solar system in the cloud can occur only with a small absorption and scattering of sunlight. Manifestations of this effect in the past history of the Earth have not yet been established. All large planets – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto – revolve around the sun in the same direction (in the direction of its rotation of the Sun itself), in almost circular orbits, slightly inclined to each other (and to solar equator). The plane of the Earth’s orbit – the ecliptic is taken as the main plane when counting the inclinations of the orbits of the planets and other bodies orbiting the Sun. Distances from planets to the Sun form a regular sequence – the gaps between adjacent orbits increase with distance from the Sun. These patterns of planetary motion, combined with their division into two groups according to their physical properties, indicate that the solar system is not a random collection of cosmic bodies, but arose in a single process. Due to the almost circular shape of planetary orbits and the large gaps between them, the possibility of close rapprochement between the planets, in which they could significantly change their motion as a result of mutual attraction, is excluded. This ensures the continued existence of the planetary system. The planets also rotate around their axis, and almost all planets except Venus and Uranus, rotate in the same direction as their revolution around the Sun. Extremely slow rotation of Venus occurs in the opposite direction, and Uranus rotates as if lying on its side. Most satellites revolve around their planets in the same direction in which the axial rotation of the planet occurs. The orbits of such satellites are usually circular and lie near the plane of the equator of the planet, forming a reduced likeness of the planetary system. Such, for example, are the system of satellites of Uranus and the system of Galilean satellites of Jupiter. Satellites located far from the planet possess reverse motions. In addition to individual satellites of noticeable size, Saturn, Jupiter and Uranus have many small satellites, as if merging into solid rings. These satellites move in orbits so close to the planet that its tidal force does not allow them to unite into a single body. The vast majority of the orbits of the currently known minor planets are located between the orbits of Mars and Jupiter. All small planets revolve around the Sun in the same direction as large planets, but their orbits are, as a rule, elongated and inclined to the plane of the ecliptic. Comets move mainly in orbits close to parabolic. Some comets have elongated orbits of relatively small sizes – tens and hundreds of au In these comets, called periodic, direct movements predominate, i.e. movement in the direction of planetary rotation. Being a rotating system of bodies, the solar system has a moment of momentum (MCD). The main part of it is associated with the orbital motion of the planets around the Sun, with massive Jupiter and Saturn giving about 90%. The axial rotation of the Sun comprises only 2% of the total MCD of the entire Solar system, although the mass of the Sun itself is more than 99.8% of the total mass. This distribution of MCD between the Sun and the planets is due to the slow rotation of the Sun and the huge size of the planetary system – its diameter is several thousand times larger than the diameter of the Sun. MCDs of the planet were acquired in the process of their formation: he passed on to them from the substance from which they were formed. Planets are divided into two groups that differ in mass, chemical composition (this is manifested in differences in their density), rotation speed and the number of satellites. The four planets closest to the Sun, the planets of the Earth group, are small, composed of dense rocky matter and metals. The giant planets – Jupiter, Saturn, Uranus and Neptune – are much more massive, they consist mainly of light substances and therefore, despite the enormous pressure in their bowels, have a low density. For Jupiter and Saturn, the main fraction of their mass is hydrogen and helium.