Solar system

  Solar system.
Around the Sun, nine large planets move in the following order, starting from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. All of these planets orbit in one direction, which is called direct. The orbits of giant planets are ellipses are very close to circles, and the planes of their orbits are tilted to the ecliptic plane at small angles. Masses of all the planets put together, make up only 0.0013 (3) solar masses. In addition to these large planets, mostly between Mars and Jupiter, is moving a large number of smaller bodies, called minor planets or asteroids. The number of known small planets as a result of new discoveries continually increasing and to date there are more than 1600.Planet of the solar system in size sharply divided into two groups. The first group is relatively small planet closest to the Sun: Mercury, Venus, Earth, Mars. This group is often called a group of Earth. The second group includes the largest planet of the solar system: Jupiter, Saturn, Uranus and Neptune. This group is a group of Jupiter. Both groups are separated by a belt minor planets or asteroids. Alone is studied, a small planet Pluto. Considering the other physical characteristics of planets, we see that many of them world sharply divided on the same two groups. For example, the average density of planets in the solar system first group is 4,5 g/cm3 and an average density of 1.21 g/cm3 Jupiter. Judging from the density, we can say that the planets of the Earth are solids. The density of Jovian planets, close to the density of the Sun, does not allow this conclusion.The solar system, planets, solar systemThere's a pretty simple explanation for the strong differences between the four giant planets and the four terrestrial planets. (The outermost planet Pluto is an exception to this scheme, it seems, is more similar to one of the satellites of distant planets).Hydrogen-rich planets are relatively little altered the original substance from which the solar system formed, and the solid terrestrial planets have lost much of the light gases, which form the basis of this substance. Instead, the primary atmosphere captured from the gas-dust cloud from which the solar system formed, they have a secondary atmosphere that arose after the formation of planets in the solar system.Comparing the periods of rotation around an axis, and here we notice a big difference between the two groups. Terrestrial planets make revolution around the axis for the period, more than a day, ie, they rotate slowly. The planet Jupiter, the same group revolve around the axis is much faster in their average rotation period is less than half a day. Jupiter is the tremendous commit turnover just 9h 50m, it is clear that its linear velocity at the equator will be much greater than the corresponding rate of rotation of the Earth (28 times). In this regard, the planet of Jupiter are of great compression, reaching Saturn's 0,1, and terrestrial planets are almost perfect spheres. The number of planetary satellites in both groups are also very different. All of the first group has only three satellites, the group also Jupiter has more than 30 satellites, and this number is updated with new discoveries.When the sun 4.6 billion years ago started thermonuclear reactions, temperatures of the planets, especially interior noticeably increased. Two crucial factors that determine the future face of the planet - the size of protoplanets and its distance from the Sun. Small size of the planet is unable to keep the hydrogen and helium, the lightest gases. During the formation of the solar system, plays a decisive role whether the planet to keep the hydrogen and helium. Another determining factor was the distance from the Sun, from which was also dependent on whether the hydrogen and helium to overcome the force of gravity of the planet. The fact that the closer the planet to the Sun, the higher it is heated, and the more difficult to retain light gases on the surface. The results of the combined effect of these factors had a significant influence on the formation of planets in the solar system and divide them into two main groups.