A 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. Solar systems can also have more than one star. These are called binary star systems if there are two stars, or multi-star systems if there are three or more stars.
Our Solar System has eight planets which orbit the sun. In order of distance from the sun they are; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto, which until recently was considered to be the farthest planet, is now classified as a dwarf planet. Additional dwarf planets have been discovered farther from the Sun than Pluto. Some asteroids are also dwarf planets.