Uranus
Uranus (Fig.) appears as a green disc with vague markings, even through the largest telescopes. Its colour is produced by the large amounts of methane and ammonia clouds in its outer atmosphere. The temperature of the ammonia clouds is about -217°C. Uranus is made up of gases such as hydrogen, helium and methane juslike,Jupiter and Saturn. Uranus is unique in the Solar System because its axis of rotation is tilted at an angle of 980 to the perpendicular and lies almost in the plane ofits orbit around the Sun, with one pole sometimes pointing directly towards the Sun. Iwould seem that the planet has toppled over its side, rolling along the orbit like a wheel. Thus, the Sun shines directly on its poles. Uranus has fifteen satellites. In 1977 nine faint rings of rocky debris were also discovered around Uranus.