Key facts
- Mean diameter
- 49,244 km
- Mass
- 1.02 × 10^26 kg (17.1 Earths)
- Surface gravity
- 11 m/s² (1.12 g)
- Escape velocity
- 23.5 km/s
- Mean temperature
- -200 °C
- Rotation period
- 16.1 hours
- Orbital period
- 59,800 days
- Mean distance from the Sun
- 4,515 million km
- Sunlight travel time
- 4 h 11 min
- Axial tilt
- 28.3°
- Confirmed moons
- 16
Atmosphere
Hydrogen, helium and methane, with supersonic winds exceeding 2,000 km/h.
Composition and structure
Ice giant with a water–ammonia–methane mantle and rocky core.
Discovery and exploration
Located in 1846 by Johann Galle using positions predicted by Urbain Le Verrier from irregularities in Uranus's orbit. Voyager 2 flew past in 1989.
Major moons
- Triton — Neptune's largest moon, orbiting backwards with active nitrogen geysers.