The complexity of the mechanisms of formation and evolution of planets is such that the same initial condition does not necessarily lead to identical results. Just as it is impossible to predict where the stone would roll a branched groove or on which side of the island for a make a raft, nature offers a wide range of different ways to develop initially a little different planetary bodies. A well-known example is the planet Venus quite unlike the Earth (although it only managed to find these days). As for other planetary systems, the diversity is evident even in their very structure. In the twentieth century, the starting point in quest for other planetary systems was considered a well-studied structure of the solar system. The four terrestrial planets: Mercury, Venus, Earth to the Moon and Mars are close to the central star, the Sun. They all have a higher average density and have atmospheres. Earth-like planets located in the central part of the solar system. Much further, from 5 to 30 units, much greater distances separate giant planets. They are arranged quite differently than the earth and have a gas-liquid nature. This group is headed by Jupiter, whose mass is 318 times the mass of the Earth and is one-thousandth (or more precisely, 1 / 1047) of the Sun. All giants have rings of different densities and a large number of moons: Saturn of more than 60. Between Mars and Jupiter are the orbits of hundreds of thousands of small planets with small, mostly about a hundred miles. Another group of solar system - comets - a typical size of small asteroids is very elongated orbits. Moreover, unlike the planets whose orbits are located approximately in one plane, close to the Earth's orbital plane (the ecliptic), comets can come from anywhere. All the planets and satellites rotate around its polar axis and the rotation one way or another is synchronized with circulation. Velocities of orbital motion of the planets are very different. The quest for other planetary systems in the twentieth century relied on the representations set forth about the solar system. In search of extra solar planets (extra planets, as they are called) several aspects: the new fundamental knowledge about the origin of the world in which we live and new ideas about the evolution of our own planet, the nature of which is not frozen in its development and is not as straightforward and stable, as it once seemed. This is the quest of the worlds with the very mysterious circumstances in which there was once (in the only known amino-acid form nucleic) and evolved life on our planet.
|
|