♆Neptune
The deep-blue planet at the edge of the Solar System. A world of supersonic winds, "predicted" by calculation before it was ever seen.
- Distance from Sun
- 30.1 AU (about 4.5 billion km)
- Diameter
- 49,244 km (3.9× Earth)
- Orbital period
- 165 years
- Rotation period
- 16.1 hours
- Moons
- 16+ (Triton, ...)
Science
The scienceNeptune is the eighth and most distant planet from the Sun, glowing a deep, rich blue created by methane in its atmosphere. It lies so far from the Sun that a single orbit takes a full 165 years; discovered in 1846, it only completed its first orbit in 2011. Despite its calm appearance, it is a fiercely violent world, blasted by the fastest winds in the Solar System (about 600 m/s, faster than the speed of sound). Neptune was not stumbled upon by telescope but found at the exact spot mathematicians predicted after noticing that Uranus's orbit was slightly off, reasoning that "another planet must lie beyond it," a triumph of theory.
Name & Myth
The story behind the nameAppearing deep blue like the ocean depths, Neptune was given in the West the name of Neptunus, god of the sea (the Greek Poseidon). Its largest moon was named after Triton, Poseidon's son; Triton is an unusual moon that orbits opposite to the planet's rotation and is thought to have been captured later. In East Asia it was rendered "Hae-wang-seong," meaning "King of the Sea," to pair it with Uranus, the King of the Sky.