The Solar System
formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system’s mass is in the Sun The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly, including the eight planets and five dwarf planets.
Six of the planets, at least four of the dwarf planets, and many of the smaller bodies are orbited by natural satellites, usually termed “moons” after the Moon. Each of the outer planets is encircled by planetary rings of dust and other small objects.The solar wind, a stream of charged particles flowing outwards from the Sun, creates a bubble-like region in the interstellar medium known as the heliosphere. The heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of the interstellar medium; it extends out to the edge of the scattered disc.