Neptune cannot be viewed with the naked eye in the sky.
Mean Distance from the Sun is (4.497 billion km/2.794 billion mi)
Neptune orbits the sun once every 165 years.
We have visited Neptune once with the Voyager 2 probe in 1989.
Neptune is the Roman god of the sea. Interesting fact about the naming of Neptune. Urbain J.J. Leverrier felt that since he discovered the planet, he had the right to name it after himself. However, his desire was trampled by people outside France. Since, all the other planets were named after Roman Gods, the international astronomy community came to a consensus that this planet should also be named after a Roman God. Thus, Neptune, being a blue planet was named after the Roman God of the sea.
Because of its distance from the Sun, Neptune's atmosphere is a frigid -225� C (-373� F).
Neptune will be closer to the Sun than Pluto for 220 years and then reverse positions for 20 years.
The largest storm on Neptune is known as the Great Dark Spot and would nearly cover the Earth if on our planet.
The Great Dark Spot has not appeared on recent Hubble Telescope images. It is unclear if this means the storm has died or is on the other side of the planet.
A Neptune day is equivalent to 16 hours on Earth.
Neptune is about four time the size of Earth.
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.
The atmosphere of Neptune is similar to Jupiter with massive wind movements.
Neptune has three rings similar to Jupiter and named Adams, Leverrier and Galle after the two individuals that predicted its existence and the one who actually found it.
Neptune has one larger moon, Triton, and 12 smaller moons that are not much bigger than asteroids.
Triton is nearly the size of our moon, but rotates in the opposite direction of the rotation of Neptune.
The moons are all named after Greek gods and such of the sea.
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.