The Nine Planets is somewhat misleading. In addition to the planets and their satellites the solar system contains a large number of smaller but interesting objects.
T here are thousands of known asteroids and comets and undoubtedly many more unknown ones.
Most asteroids orbit between Mars and Jupiter . Most comets have highly elliptical orbits which spend most of their time in the outer reaches of the solar system with only brief passages close to the Sun. T he distinction between comets and asteroids is somewhat controversial . The main distinction seems to be that comets have more volatiles and more elliptical orbits. Very small rocks orbiting the Sun are sometimes called meteoroids to distinguish them from the larger asteroids.