Neptune is the eighth and farthest known planet from the Sun in the Solar System. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet.

Distance from Sun: 2.793 billion mi

Orbital period: 165 years

Radius: 15,299 mi

Mass: 1.024 × 10^26 kg (17.15 M⊕)

Moons: Triton, Nereid, Proteus, Thalassa, Despina, Galatea, Neso, MORE

Did you know: Its atmosphere mainly comprises of helium and hydrogen.