<human>:  Give me information about the planet Neptune
<bot>: Neptune is the eighth and farthest known planet from the Sun in the Solar System. It is the fourth-largest planet by diameter and the third-most-massive planet. It is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times the mass of Earth and slightly larger than Neptune. Neptune orbits the Sun once every 164.8 years at an average distance of 30.1 AU. It has eight known moons. The most notable of these is Triton, discovered by William Lassell in 1846. Triton is unusual because it is the only large moon in the Solar System with a retrograde orbit.