Neptune

Neptune (or Sol VIII) is the eighth planet from Sol, in the Sol system. The Earth Starfleet Neptune-class starships were named after this planet. (ENT: "Singularity")

At warp 4.5, it would take six minutes to go to Neptune and back from Earth. While inspecting Enterprise NX-01 for the first time, Captain Archer noted this to Commander Tucker – an impressive feat for its day. (ENT: "Broken Bow")

Neptune was seen on a map depicting the Sol system watched by Nomad. (TOS: "The Changeling")

According to Arex, the cosmic cloud encountered by the USS Enterprise in 2269 was twice the diameters of Jupiter, Saturn and Neptune in size. (TAS: "One of Our Planets Is Missing")

A product known as "Neptune Bath Salts", based on the name of the Roman God, was manufactured on the fourth planet of the 892 system in 2268. (TOS: "Bread and Circuses")

Background

In 1975, the Mego toy company produced a reptilian action figure doll called a "Neptunian," although such a creature never appeared at any time during the Star Trek franchise.