Arizona's College and Career Ready Education Standards. All planets in our solar system rotate and they all revolve around the Sun. Inner planets: Mercury, Venus, Earth. Outer planets: Jupiter, Saturn, Uranus, Neptune. Comets are made of ice and rock. They have four parts: a nucleus which is the solid portion of the comet and is made of dust and ice, a coma which is a cloud of dust and evaporated gases, an ion tail and a dust tail. Read More...