SCIENTIFIC FACT SHEET · ICE GIANT
Neptune
Neptune is the Solar System's outermost planet. Despite its distance from the Sun, its atmosphere has some of the fastest winds ever measured on a planet.
A world of powerful winds
Values are rounded for readability. The figures and 3D representation are explained in the Method section.
Composition and interior
Neptune probably has a rocky core surrounded by a deep mixture of water, methane and ammonia, beneath outer layers dominated by hydrogen and helium.
Atmosphere and environment
Its atmosphere also contains methane and has the fastest winds measured on any planet, sometimes exceeding 2,000 km/h. Dark storms appear and disappear there.
Exploration
Voyager 2 flew past Neptune in 1989 and remains the only spacecraft to have visited it. Hubble and James Webb now observe its storms, rings and seasons.
A remarkable fact
Triton, its largest moon, orbits in the opposite direction to Neptune's rotation. This retrograde orbit suggests it was once a Kuiper Belt object that Neptune captured.
THE ESSENTIALS
Three things to remember about Neptune
- A year on Neptune lasts nearly 165 Earth years.
- Sunlight takes more than four hours to reach it.
- Triton is its largest moon.