Uranus, Neptune and Pluto

Episode number 24 of Series “Universe: the infinite frontier: an introductory astronomy telecourse”.
William Herschel dicovered the planet Uranus in the late 1700’s. In 1986, the satellite Voyager flew past and sent back pictures of this ice planet. Neptune and Uranus have similar composition, but Uranus, unlike other planets, has an unusual rotation and large tilt, where it may have been hit by a celestial object. Uranus has rings and around it floats the debris from the formation of the solar system. Neptune, although similar to Uranus, has a different atmosphere and a dark spot, similar to Jupiter, as well as thin ring arcs. Triton, one of Neptune’s moons, is the coldest place in the solar system. Pluto was the last planet to be discovered, and because Voyager did not pass by, scientists have had to use other methods such as spectroscopy to determine its composition. It is the smallest planet in our solar system and may be a remanant of planet formation when the solar system was first formed.