Atmosphere
Hydrogen, helium and methane, with white methane-ice clouds and giant storms like the Great Dark Spot.
Distance from Earth today
4324.4M km
In astronomical units
28.907 AU
Light travel time
4h 0m
Overview.
Neptune is the most distant planet from the Sun, a deep blue ice giant found by mathematics before it was seen.
Its supersonic winds blow at over 2,000 km/h, driving huge dark storms.
- Diameter
- 49,244 km
- Distance from Sun
- 4.5B km
- Year
- 165 Earth years
- Day
- 16h 6m
- Gravity
- 1.14 g
- Moons
- 16
The real Neptune
Through spacecraft eyes.
Voyager 2’s view of Neptune shows the Great Dark Spot and bright methane-ice clouds. Image processing enhances the planet’s blue color.
Image credit: NASA / JPL
Surface & interior
No solid surface; a thick slushy mantle of water, ammonia and methane surrounds an Earth-sized rocky core.
Moons & rings
16 known moons. Triton orbits backwards, has nitrogen geysers, and is probably a captured object from the Kuiper Belt.
Missions.
- Voyager 2 (1989, the only visit)
Wow facts.
- It has completed only one orbit since its discovery in 1846.
- Sunlight takes about 4 hours to reach it.
- Triton is slowly spiraling inward toward Neptune.
Yana asks
How did scientists find Neptune using only math?
Cover: artistic illustration. Spacecraft images and radar visualizations: credited NASA mission data.