With an average orbital speed of 5.43 km/s, it takes Neptune 164.8 Earth years (60,182 Earth days) to complete a single orbital period, which means no human being living on Neptune would ever reach his/her first birthday!

Unexpected changes in the orbit of Uranus led Alexis Bouvard to deduce that its orbit was subject to gravitational perturbation by an unknown planet, making Neptune the first planet discovered by mathematical prediction rather than empirical observation.

It has the strongest sustained winds of any planet in the Solar System, with recorded wind speeds as high as 2,100 km/h (1,300 mph).

Neptune has four seasons, just like Earth. But unlike Earth, each season on Neptune lasts more than 40 years!

Much like it's near-twin Uranus, Neptune is blue due to traces of methane in its atmosphere.

When Holst scored this work as a piece for piano duet, he used an organ to represent this planet -- the piano, he thought, could never portray anything as mysterious as Neptune. Beautiful harp and string melodies slide over each other, until Holst brings out the crowning glory: a mystical choir, which gives the music an other-worldly quality.

Neptune is 17 times the size of Earth but just 1/19th that of Jupiter.

The first suggestion came from Johann Galle, who proposed the name Janus. In England, Cambridge Observatory director James Challis put forward the name Oceanus. Objecting to others naming his discovery, Le Verrier quickly proposed the name Neptune, after briefly trying to name the planet Le Verrier, after himself.

Backwards-orbiting Triton is thought to have been a dwarf planet captured from the Kuiper belt by Neptune's immense gravitational pull. It was discovered just 17 days after the discovery of Neptune itself.

Neptune's moons are named for minor water deities in Greek mythology.