Interesting facts about Neptune...
Neptune’s moon Triton is the largest moon to orbit backwards around a planet
Neptune has 13 moons!
It takes 165 Earth years for Neptune to complete one orbit around the sun
The atmosphere is made of hydrogen methane and helium
Like Jupiter, Saturn and Uranus, Saturn is a gas giant. Although it is the smallest of the four.
Neptune’s cloud called the ‘scooter’ moves around Neptune every 16 hours.
After Pluto was declassified as a planet, Neptune became the farthest planet from the sun.
Neptune has a rocky core.
Neptune is so far away that it took the space probe Voyager 2, 12 years to reach it.
After the discovery of Uranus, it was noticed that its orbit was not as it should be in accordance with Newton's laws. It was therefore predicted that another more distant planet must be perturbing Uranus' orbit. Neptune was first observed by Galle and d'Arrest on 1846 Sept 23 very near to the locations independently predicted by Adams and Le Verrier from calculations based on the observed positions of Jupiter, Saturn and Uranus. An international dispute arose between the English and French (though not, apparently between Adams and Le Verrier personally) over priority and the right to name the new planet; they are now jointly credited with Neptune's discovery. Subsequent observations have shown that the orbits calculated by Adams and Le Verrier diverge from Neptune's actual orbit fairly quickly. Had the search for the planet taken place a few years earlier or later it would not have been found anywhere near the predicted location.
Because Pluto's orbit is so eccentric, it sometimes crosses the orbit of Neptune making Neptune the most distant planet from the Sun for a few years.
Neptune's composition is probably similar to Uranus': various "ices" and rock with about 15% hydrogen and a little helium. Like Uranus, but unlike Jupiter and Saturn, it may not have a distinct internal layering but rather to be more or less uniform in composition. But there is most likely a small core (about the mass of the Earth) of rocky material. Its atmosphere is mostly hydrogen and helium with a small amount of methane.
Neptune's blue color is the result of absorption of red light by methane in the atmosphere