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Outermost Planet of the Solar System

Proper NameNeptune
Orbital Period164.90 years
Distance from the SunSemi-Major Axis: 4,504,449,760 km (30.11 AU)
Perihelion: 4,461,855,683 km (29.83 AU)
Aphelion: 4,547,043,837 km (30.40 AU)
Rotation Period18 hours, 12 minutes
Diameter50,538 km
Mean Surface Temperature80 K (-193°C)
MoonsDespina, Galatea, Halimede, Hippocamp, Laomedeia, Larissa, Naiad, Nereid, Neso, Proteus, Psamathe, Sao, Thalassa, Triton; other small moons
Parent starThe Sun, yellow dwarf star
Other planets in this systemMercury, terrestrial planet
Venus, terrestrial planet
Earth, terrestrial planet
Mars, terrestrial planet
Jupiter, gas giant
Saturn, gas giant
Uranus, ice giant
Numerous dwarf planets, asteroids and other bodies
NotesThe outermost of the eight major planets of the Solar System, the ice giant Neptune pursues a distant orbit that carries it around the inner edge of the region known as the Kuiper Belt.

Use the scrollbar on the right of this window to explore the moons of Neptune, shown to scale. (Values shown are mean distances from Neptune, though note that some of the planet's outer satellites have highly eccentric orbits).

Blue Neptune is farthest major planet from the Sun. This gas giant follows its course on the outer fringes of the Solar System.


The cold, blue world of Neptune, outermost of the gas giants.

Size Comparison of Neptune

With a diameter of 49,500km, Neptune is the smallest of the Solar System\'s four giant planets. In comparison to our own Earth, though, it is gigantic.


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