Neptune
The eigth planet, Neptune, was discoveted in 1846 by astronomer Johann Gottfried Galle. We have already told you the story of its discovery in last. It is so far awaythat, seen from Neptune, the Sun must appear just as a bright point. Neptune's atmosphere has methane hut no detectable ammonia. Its cloud temperature is about -237°C. Neptune is orbited by Triton, one of the biggest satellites in the Solar System.It orbits Neptune in a clockwise drrection, i.e. opposite to the planet's own rotation. It has an atmosphere of nitrogen and methane. It may even have an ocean of liquid nitrogen. 'lhton is acmmpanied by a smaller satellite, Nereid. In 1989, Voyager 2- passed within 35,000 km of Neptune and within 40,000 km of Triton resulting in a significant increase in our knowIedge about Neptune and its satellites.