How long is one year on Neptune in Earth years?
The average distance between Neptune and the Sun is 4.55 billion km (about 30.1 times the average distance from the Earth to the Sun, or 30.1 AU) and it completes an orbit every 164.79 years. On July 12, 2011, Neptune will have completed the first full orbit since its discovery in 1846,[86][4] although it will not appear at its exact discovery position in our sky due to the Earth being in a different location in its 365.25 day orbit. The elliptical orbit of Neptune is inclined 1.77° compared to the Earth. Because of an eccentricity of 0.011, the distance from Neptune and the Sun varies by 101 million km between perihelion and aphelion, or the nearest and most distant points of the planet along the orbital path respectively.[2] The axial tilt of Neptune is 28.32°,[87] which is similar to the tilt of Earth and Mars. As a result this planet experiences similar seasonal changes. However, the long orbital period of Neptune means that the seasons last for forty Earth years.[72] Its sidereal
