Neptune is the eighth planet from the Sun and the smallest of the gas giants. Neptune was the first planet found by mathematical prediction after unexpected changes in the orbit of Uranus were observed. Neptune is named after the Roman god of the sea.
- Circumference at Equator:155,600 km
- Diameter: 49,493 km
- Mass: 102,410,000,000,000,000 billion kg (17.15x Earth)
- Average Distance from Sun: 4,498,396,441 km (30.10 AU)
- Known Satellites: 13
- Notable Satellites: Tritan
- Length of Orbit: 60,190.03 Earth days (164.79 Earth years)
Facts about Neptune
- Neptune has only been passed by one spacecraft, Voyager 2 which flew by on the 25th of August 1989.
- Although smaller in diameter than Uranus, Neptune has a greater mass.