Saturn's north pole, infrared Cassini satellite image. Saturn is a gaseous planet composed mainly of hydrogen and helium. This image was obtained in light absent conditions during winter. The red colour is due to thermal radiation emanating from deep within the atmosphere. Darker areas are where gas clouds block out the radiation. The bluish tinge at top is where sunlight is striking the planet. The pole is encircled by a hexagonal feature in its atmosphere. This feature was first observed by the Voyager spacecraft in 1980. It is thought that it may be caused by a planetary (atmospheric) wave. This image was obtained by the visual and infrared mapping spectrometer onboard the Cassini Orbiter, 30th October 2006.