The solar system comprises the Sun and all the objects that orbit around it. These objects include planets, dwarf planets, moons, asteroids, comets, and other small bodies. The most well-known components of the solar system are the eight planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune) and their respective moons. These objects all revolve around the Sun, which is at the center of the solar system. Therefore, the correct option is "the sun and its nine planets."