Neptune

Neptune is the eighth and outermost planet in the Earth's solar system. It is the fourth-largest planet by diameter and the third-largest by mass; Neptune is 17 times the mass of Earth and is slightly more massive than its near twin Uranus. The planet is named after the Roman god of the sea.

In the book Gonzo and the Great Race, Baby Gonzo makes a pit stop on Neptune for a pickle and ketchup sandwich, while en route to Pluto.