Neptune is the outermost of the four gas Giants: Jupiter, Saturn Uranus, Neptune.
Because of its distance from the Sun, Neptune's atmosphere is a frigid -225 degrees Celsius (-373 degrees Farenheit).
The blue-green color of the planet is due to the presence of methane in the atmosphere. The atmosphere consists mostly of hydrogen, helium and methane.
Until the Voyager encounter in 1989, the rings surrounding Neptune were thought to be arcs. We now know that the rings completely circle the planet, but the thickness of each ring varies along its length.