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Neptune - Rotating Model
Credit: Almond/NASA

Neptune is a blue Gas Giant like Uranus and is the furthest planet from the Sun, at around 30 times further away than the Earth is. The gravitational pull on the surface of the planet is one of the strongest in the Solar System, with only Jupiter having a stronger pull.

Neptune was first 'discovered' through observations of the orbit of Uranus, which looked like it was being pulled by another planet, therefore it was found through a mathematical formula (by Alexis Bouvard), rather than an observation!

Like Uranus, it contains a higher proportion of "ices" such as water, ammonia and methane, and it is the methane that gives Neptune its blue colour. The white streaks you see are high level cloud layers that indicate active weather systems in the planet's atmosphere. Neptune's winds are the fastest known on any planet, with speeds approaching 2000 km per hour.

Triton, taken by Voyager 2
Credit: NASA

Neptune has at least a dozen small moons and one large one called Triton.

Voyager 2 is the only spacecraft to visit Neptune back in 1989, it took some images of the moons as it flew past including the mosaic of Triton to the left.

Planet Data Sheet show »« hide
Facts and FiguresMercuryVenus EarthMarsJupiter SaturnUranusNeptune
Orbital Distance (AU)10.380.72 1.01.525.2 9.4519.230.06
Radius (KM)2,4406,052 6,3783,39771,492 60,26825,55924,746
Mass (Earth Masses)20.0550.82 1.00.11318 95.214.517.1
Year Length
(Earth Days)
88225 365.2568711.9
Day Length
(Earth Days)
176117 0.430.750.67
Surface Gravity (g)30.380.91 1.00.382.34 0.930.921.12
Surface Temperature-200 to
400 °C
460 °C -80 to
50 °C
-150 to
20 °C
-110 °C -140 °C-190 °C-200 °C
Number of moons00 1263 602713
Notes: 1 1 AU (or Astronomical Unit) = 149,600,000 KM and is the mean distance from the Earth to the Sun
2 1 Earth Mass = 5,980,000,000,000,000,000,000,000 KG : 3 1 g = 9.8 m/s2