Solar system - a planetary system consisting of the Sun and the associated gravity of celestial bodies . These bodies are the eight planets , 166 known moons of the planets, five well-known (and probably a few dozen [1 ] ) dwarf planets and billions ( and maybe even trillions ) [2 ] small solar system bodies , which include asteroids , comets , meteoroids and interplanetary dust .
Explored regions of the solar system contain , counting from the Sun : the four terrestrial planets (Mercury , Venus, Earth, Mars ) , the asteroid belt composed of small rocky bodies , four outer gas giants (Jupiter , Saturn , Uranus , Neptune ) and the second band is objects rock and ice , the so-called Kuiper belt . Behind the Kuiper belt is the scattered disc , much further heliopause and finally hypothetical Oort cloud . Also found at least [1 ] five dwarf planets : Ceres (the largest object in the asteroid belt ) , Pluto (up to 24 August 2006, considered the ninth planet Agreement ) [3 ] , Haumea , Makemake ( the second largest object in the Kuiper belt ) and Eris ( the largest known object in the scattered disc ) .
Six of the eight planets and three dwarf planets have natural satellites , called moons . Each of the outer planets is surrounded by a ring composed of cosmic dust . All the planets except Earth and Uranus (which takes its name from the Greek deity Uranosowi ) , named after the gods of Roman mythology .
It is estimated that the formation and evolution of the solar system began 4.6 billion years ago, when as a result of gravitational collapse of unstable parts of the molecular cloud , the process of the formation of the Sun and other stars . The system is still subject to evolution and chaotic change and will not exist forever in its present form . For about 2 - 5 billion years , it is possible Andromeda Galaxy collision with the Milky Way , and in about 5 billion years the Sun will increase many times their diameter , becoming a red giant , which will lead to the destruction of the terrestrial planets , including Earth. Then the sun off its outer layers as a planetary nebula and evolve into a white dwarf , the temperature and brightness will gradually decline until complete "death" of the star. It is believed that the Sun then turns into a black dwarf , but this theory can neither confirm nor refute , because the universe is too young to be created objects of this type .
