Solar SystemA solar system is a star and all of the objects that travel around it — planets, moons, asteroids, comets and meteoroids. Most stars host their own planets, so there are likely tens of billions of other solar systems in the Milky Way galaxy alone.
Simply put, planets in the solar system revolve around the sun and the solar system is held together by its own gravitational field. The solar system consists of nine planets, the sun, each planet's moons, comets, asteroids and meteors.
Galileo Galilei was the first to discover physical details about the individual bodies of the Solar System. He discovered that the Moon was cratered, that the Sun was marked with sunspots, and that Jupiter had four satellites in orbit around it.