Earth is the third planet from the Sun and the only planet to have an atmosphere containing free oxygen, oceans of water on its surface and life. In the solar system, Earth is the fifth largest of the planets. The Sun, the eight planets and their moons, smaller planetary objects such as dwarf planets, comets and meteoroids together make up our solar system. Earth is the only world in our solar system with liquid water on the surface. Just slightly more massive than nearby Venus, Earth is the biggest of the four planets closest to the Sun, all of which are made of rock and metal.