Solar System
Neptune
Ice Giant · Farthest Planet

The farthest planet from the Sun, Neptune is a dynamic world generating its own internal heat. Despite receiving only 1/900th of Earth's sunlight, it drives the strongest winds in the Solar System — up to 2,100 km/h.

Planet Data ○ Reference
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Mean Radius
24,622 km
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Gravity
11.15 m/s²
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Density
1.64 g/cm³
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Avg Temperature
-201 °C
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Axial Tilt
28.3°
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Escape Velocity
23.50 km/s
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Orbital Period
60,182.0 days
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Rotation Period
16.11 h
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Known Moons
16
Overview via Wikipedia
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Atmosphere Composition
Hydrogen 80%
Helium 19%
Methane 1.5%
Hydrogen Deuteride 0.019%
Other traces <0.01%
Notable Features
Winds up to 2,100 km/h — fastest in the Solar System
Great Dark Spot — large storm system (now dissipated)
Triton — largest moon, orbits backwards, likely a captured KBO
Internal heat source — radiates 2.6× more heat than it receives
Space Missions
Mission Year Notes
Voyager 2 1989 Only spacecraft to visit Neptune — 5-hour flyby
Neptune Odyssey 2040s proposed Flagship orbiter and probe concept
Moons & Satellites
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NASA Images

Images courtesy of NASA Image & Video Library. All images are public domain.

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Neptune Science Quiz

10 questions from our Science quiz

Question 1 of 10
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Solar System
NASA Photo Gallery — Neptune View on NASA ↗

Images courtesy of NASA Image & Video Library. All images are public domain.