World 08 · ice giant
Neptune
A dark blue frontier driven by supersonic winds.
Neptune is the most distant major planet, an ice giant with a dynamic atmosphere and exceptionally fast winds.
Distance-led editorial diagram. The small solar signal and deep field communicate remoteness, not a photographed sky.
- Order from Sun
- 8
- World type
- Ice giant
Personal comparison
Put the numbers against your own body
Gravity, day length and sunlight delay become more understandable when related to an Earth reference.
Your Earth reference
The delay is more tangible than the gravity
A scale comparison is possible at the one-bar reference level, but the defining human-scale fact is time: sunlight and radio signals cross an enormous distance.
Use a value from 0 to 1,000 kilograms.
Neptune scale equivalent
—kg
This is an Earth-style scale equivalent. Your mass does not change, and a giant-planet value refers to a defined atmospheric level rather than a place to stand.
Mean radius
24,622km
49,528 km equatorial diameter
Solar day
16h 06m
Prograde rotation
Temperature reference
-200°C
Atmospheric reference level, not a surface
Far light
Distance becomes part of every experience
Neptune is not simply Uranus in darker blue. Its remoteness, atmospheric activity and long orbital period create a different rhythm and a stronger sense of depth.
Distance
Sunlight arrives after hours, not minutes
At Neptune's average orbital distance, sunlight takes several hours to arrive. Communication and observation inherit that delay even before mission operations add their own constraints.
The Sun would remain intensely bright to the eye but occupy a much smaller apparent disk than it does from Earth.
Atmosphere
A cold world with vigorous motion
Neptune's atmosphere is hydrogen- and helium-rich with methane, yet it supports highly dynamic weather and exceptionally fast winds.
The reference temperature is tied to an atmospheric pressure level, not a solid surface and not a current storm measurement.
Reference signals
The conditions that define this world
A hydrogen-helium atmosphere with methane and highly active weather.
Moon
Triton moves against the usual direction
Triton is Neptune's largest featured moon and follows a retrograde orbit, making the moon system as distinctive as the atmosphere.
Rings
Faint rings with concentrated arcs
Neptune's ring system is subtle and includes prominent arcs rather than Saturn-like bright continuous bands.
Year
One orbit exceeds a human lifetime
Neptune requires roughly 165 Earth years to circle the Sun, separating daily atmospheric motion from an extraordinarily long seasonal clock.
- Axial tilt
- 28.3°
- Recognized moons
- 16 · 2026-07-17
- Rings
- Neptune has a faint ring system with prominent arcs.
- Atmosphere
- hydrogen · helium · methane
Exploration record
How we learned to read this planet
Mission summaries are tied to dated official records and are not presented as live telemetry.
- 01
Completed flyby
Voyager 2
Voyager 2 is the only spacecraft to have visited Neptune, revealing moons, rings and the Great Dark Spot during the 1989 encounter.
Scientific limits
What these values do—and do not—describe
Reference values keep their definition, source and date context. Editorial diagrams are separated from measured planetary data.
Sources and provenance
- NASA Jet Propulsion LaboratoryPlanetary Physical Parameters ReferenceAccessed Jul 17, 2026
- NASA Jet Propulsion LaboratoryApproximate Positions of the Planets ReferenceAccessed Jul 17, 2026
- NASA SciencePlanet Sizes and Locations in Our Solar System ReferenceAccessed Jul 17, 2026
- NASA ScienceTemperatures Across Our Solar System ReferenceAccessed Jul 17, 2026
- NASA ScienceNeptune: Facts ReferenceAccessed Jul 17, 2026
- NASA Jet Propulsion LaboratoryPlanetary Satellite Discovery Circumstances Latest availableAccessed Jul 17, 2026
- NASA ScienceVoyager 2 HistoricalAccessed Jul 18, 2026
NASA mission media
Neptune, through a mission archive
Every preview comes from the reviewed NASA media list for that world. A failed request can only fall back to media curated for Neptune.
PIA01492
This picture of Neptune was produced from the last whole planet images taken through the green and orange filters on NASA's Voyager 2 narrow angle camera. The images were taken at…
Voyager 2NASA media details
Neptune Rings
In Neptune outermost ring, 39,000 miles out, material mysteriously clumps into three arcs. Voyager 2 acquired this image as it encountered Neptune in August of 1989.
NASA/JPLNASA media details
Triton Video
NASA Voyager 2 spacecraft flew by Triton, a moon of Neptune, on August 25, 1989. This frame from a video using Voyager data recreates that exciting encounter.
NASA/JPL-Caltech/Lunar & Planetary InstituteNASA media details