6. Neptune - the Mysterious Giant

Neptune, the outermost of the giant planets, has been known for well over a century, but our knowledge of it is still meagre. With its gaseous surface, its quick rotation and its large satellite, Triton, it is of tremendous interest. Patrick Moore and Dr Garry Hunt discuss what is known about Neptune and what future researches may tell us when Voyager 2 passes this ' outermost giant' in 1989.