Planets
Neptune
[May 03, 2007] Neptune is the eighth planet from the Sun and the fourth largest (by diameter). Neptune is smaller in diameter but larger in mass than Uranus. orbit: 4,504,000,000 km (30.06 AU) from Sun diameter: 49,532 km (equatorial) mass: 1.0247e26 kg Hardcopy The New Solar System Summarizes what we have learned from interplanetary explorations in the last 25 years. My primary reference for The Nine Planets. Encyclopedia of the Solar System A more scholarly introduction the planetary science for those who want to dig a little deeper. The Compact NASA Atlas of the Solar System This road map of the solar system contains lots of maps and data as well as photos. In Roman mythology Neptune (Greek: Poseidon) was the god of the Sea. After the discovery of Uranus, it was noticed that its orbit was not as it should be in accordance with Newton's laws. It was therefore predicted that another more distant planet must be perturbing Uranus' orbit. Neptune was first observed by Galle and d'Arrest on 1846 Sept 23 very near to the locations independently predicted by Adams and Le Verrier from calculations based on the observed positions of Jupiter, Saturn and Uranus. An international dispute arose between the English and French (though not, apparently between Adams and Le Verrier personally) over priority and the right to name the new planet; they are now jointly credited with Neptune's discovery. Subsequent observations have shown that the orbits calculated by Adams and Le Verrier diverge from Neptune's actual orbit fairly quickly.