Saturn with its rings at their widest angle to Earth, optical HST image. Saturn, like Earth, has a large axial tilt (it rotates on a different plane to the one in which it travels around the Sun). With Earth, this effect causes the seasons. With Saturn, it is useful as it allows Saturn's polar regions to be studied from Earth. Its south pole is seen here. Saturn orbits the Sun once every 29.5 years, making opportunities such as this rare. It orbits around 1500 million kilometres from the Sun. Its rings, composed mainly of water ice and rock, span nearly 300,000 kilometres. Photographed on 7th March 2003.