Uranus had a slight wobble (perturbation) that could only be caused by another planet near by. This planet was Neptune. It was then spotted with telescopes and confirmed.
History of it’s discovery
Neptune is not visible to the unaided eye and is the only planet in the Solar System found by mathematical prediction rather than by empirical observation. Unexpected changes in the orbit of Uranus led Alexis Bouvard to deduce that its orbit was subject to gravitational perturbation by an unknown planet. Neptune was subsequently observed with a telescope on 23 September 1846 by Johann Galle within a degree of the position predicted by Urbain Le Verrier.
Adapted from: Neptune. (2016, September 18). In Wikipedia, The Free Encyclopedia. Retrieved 07:35, September 23, 2016, from https://en.wikipedia.org/w/index.php?title=Neptune&oldid=740019815
- Distance from sun: between 4,452,940,833 and 4,553,946,490 km (why the variation?)
- Orbital period (it's year): 164.79 years
- Moons(Natural Satellites): 13
- Triton, largest moon (1846)
- Faint ring
- Type of planet: Gaseous giant (ice giants)
- Length of day: 16.11+-0.01 hr
- Average radius(equator): 24, 766+-15 km
- Mass: 102.41 x 1024 kg
- Gravity near cloud tops: 11.15 m/s2
- Temperature of cloud tops: 72+-2 K (extremely cold)
- Atmosphere: Thickness varies with depth to core, extreme wind speeds and planetary scale cyclonic storms.
- Pressure: varies according to depth to core.
- Atmospheric composition:
- traces of methane