The Flag of Neptune, designed by J. Alfary, represents the planet Neptune itself and its largest moon Triton.
- Blue represents Neptune's water, hydrogen, and ammonia-rich atmosphere and its status as an "ice giant" planet.
- The middle white band represents the ice storm bands that traverse the atmosphere and recognize that Neptune is one of the coldest worlds in the Solar System.
- The white astronomical symbol "Neptune's Trident" represents Neptune.
- The smaller white-blue sphere represents Neptune's largest moon Triton.
- Black represents the Great Dark Spot on Neptune and the vastness of space that separates and unifies the Solar System and the Universe.