Planet Neptune

Neptune was the first planet discovered through mathematical prediction. Urbain Le Verrier and John Couch Adams predicted the position in 1846. Neptune is smaller than Uranus, but denser. Like Uranus, Neptune is also referred to as an Ice Giant, as well as Uranus’ twin. It too may have a very small rocky core.Neptune also exhibits more atmospheric activity than Uranus. Its Great Dark Spot is a storm similar to Jupiter’s Great Red Spot, and about the same size as Earth. Neptune also has atmospheric scooters that are white cloud groups. It was so named because it moved faster than the Great Dark Spot. Its atmosphere sustains the highest winds in the solar system, in excess of 1,200 miles per hour. Like the other Gas Giant planets, Neptune also exhibits aurora activity.

Neptune has five rings, which are composed of dark particles. The rings appear to be broken, more like arcs or ringlets. There are 14 known moons (as of August 2014).

Neptune at a Glance

Characteristics to Compare


  • Hydrogen (H ), Helium (H ), Methane (CH ), Ammonia (NH ), Water (H O)


  • Short rotation — 16.1 hours


  • Long revolution — 164.8 years


  • A partial, twisted series of 5 rings confirmed by the Voyager 2 spacecraft

Magnetic Field

  • Yes, tilted about 45 . Reason for tilt unknown

Neptune Satellite of Distinction — Triton (NOT to be confused with Saturn's moon of the same name); Retrograde (captured moon?), volcanism; polar caps.

Image of the planet Neptune, showing the Great Dark Spot and Scooters.
Neptune, showing the Great Dark Spot and ScootersPublic Domain | Image courtesy of NASA.

Image of Clouds in the upper atmosphere of Neptune.
Clouds in the upper atmosphere of NeptunePublic Domain | Image courtesy of NASA.

Image of Neptune’s moon Triton shows cratered surface with mounds and round pits.
Neptune’s moon TritonPublic Domain | Image courtesy of NASA.

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