How long is Neptune period of rotation and revolution?
Neptune is the eighth and last planet in our solar system. It is named for the Roman god of the sea. It is the 4th largest planet by diameter and third by mass, 17 times more massive than Earth. It was descovered on September 23rd, 1846 and was the first planet to be found by mathematical prediction rather than observation. Neptune is largely made of hydrogen and helium, with bits of methane and ammonia in the atmosphere. Neptune has 13 moons, and a fragmented ring system comprised largely of frozen chunks of methane.
