Neptune was discovered in 1846 by J.Galle. The diameter amounts to approx. 48'600 km, that corresponds e.g. to the diameter of Uranus. Neptune structure should be quiet similar to that one of Uranus: It’s got a mass of about 1,71 g/cm^3. Distance to the Sun varies between 4456 * 10^6 and eccentricity of the orbit amounts to approximately 0.0086. The orbit angle against the ecliptic is 1° 46‘. The revolution time around the sun amounts to 164,8 years. The rotation period is not exactly know, but the exterior cloud layer rotates with about 18h 24 min. Perhaps the centre of the planet rotates slightly more slowly.