- MEAN RADIUS: 24622 km
- MASS: 17.2 (Earth=1)
- DENSITY: 1.66 (g/cm^3)
- GRAVITY: 1.19 (Earth=1)
- ORBIT PERIOD: 164.79 (Earth years)
- ROTATION PERIOD: .67 (Earth days)
- SEMIMAJOR AXIS OF ORBIT: 30.058 au
- ECCENTRICITY OF ORBIT: 0.009
The Roman god Neptune, whose Greek equivalent was Poseidon, was the god of the sea. His namesake planet is the eighth planet
from the Sun and the fourth largest (by diameter). It is smaller in diameter but larger in mass than Uranus.
Like its neighbor, Uranus, Neptune is believed to have a rocky core (about the mass of Earth), surrounded by a huge ocean of water mixed with rocky material. Its atmosphere is mostly hydrogen and helium with a small amount of methane.
Neptune is visible with binoculars (if you know exactly where to look) but a large telescope is required to see anything other than a very small dot. Through the telescope, it appears as a small greenish disk.
Like the other gas giants, Neptune has rings, four. It also has thirteen known satellites, seven with names and five, yet to be named.
Satellites
- Naiad
Distance (000km) 48 - Radius (km) 29 - Mass (kg) ? - Discovered By & Year Voyager 2 1989 - Thalassa
Distance (000km) 50 - Radius (km) 40 - Mass (kg) ? - Discovered By & Year Voyager 2 1989 - Despina
Distance (000km) 53 - Radius (km) 74 - Mass (kg) ? - Discovered By & Year Voyager 2 1989 - Galatea
Distance (000km) 62 - Radius (km) 79 - Mass (kg) ? - Discovered By & Year Voyager 2 1989 - Larissa
Distance (000km) 74 - Radius (km) 96 - Mass (kg) ? - Discovered By & Year Voyager 2 1989 - Proteus
Distance (000km) 118 - Radius (km) 209 - Mass (kg) ? - Discovered By & Year Voyager 2 1989 - Triton
Distance (000km) 355 - Radius (km) 1350 - Mass (kg) 2.14e22 - Discovered By & Year Lassell 1846 - Nereid
Distance (000km) 5509 - Radius (km) 170 - Mass (kg) ? - Discovered By & Year Kuiper 1949