Exhibit Codex
Neptune
The outermost major planet, with a deep blue atmosphere and strong winds.
Open interactive exhibit ↗About this exhibit
Ice giant
Physical profile · seven measurements
- Mean radius
- 24,622 km
- Mass
- 102.4092 ×10²⁴ kg
- Bulk density
- 1.638 g/cm³
- Sidereal rotation
- 0.67125 Earth days
- Sidereal orbit
- 164.79132 Earth years
- Equatorial gravity
- 11.15 m/s²
- Escape speed
- 23.56 km/s
Present-day reference values, rounded from JPL Solar System Dynamics. These are not reconstructed ancient measurements. Gas-giant gravity refers to a reference atmospheric level, not solid ground. Sidereal rotation differs from the solar day.
Reference and coverage
Time scaling is shared with the interactive atlas. Surface interpretations and reconstructed history have different levels of certainty.
Planetary record
A distant atmosphere
Methane contributes to Neptune’s blue appearance. Its atmosphere contains fast winds and changing dark storm systems. The cloud animation is illustrative rather than a weather forecast.
Long seasons
Neptune needs about 165 Earth years to orbit the Sun. Its interior releases heat and contains a larger proportion of heavy compounds than the gas giants.
Triton
Its largest moon follows a retrograde orbit and is thought to be a captured Kuiper Belt object. This view focuses on Neptune itself.
Time in this exhibit
4.6 billion years ago · Cloud & disk
The young Sun is surrounded by a disk of gas and dust. Planet formation is underway.
4.54 billion years ago · Young planets
The terrestrial planets are growing through accretion and impacts. Their orbits and surfaces continue to evolve.
Present · Modern system
Eight planets orbit our Sun. This layout compresses distances and adjusts sizes to make every world accessible.
Exhibit guide
Structure
Neptune is an ice giant with a dense, hot interior beneath an atmosphere of hydrogen, helium and methane. It has no accessible solid surface at the visible cloud level.
Atmosphere
Fast winds and changing dark storms move through the atmosphere. Methane affects its color, but published pictures may use different color processing.
Methane contributes to Neptune’s blue appearance. Its atmosphere contains fast winds and changing dark storm systems. The cloud animation is illustrative rather than a weather forecast.
Orbit & rotation
An orbit takes about 165 Earth years. Rotation takes roughly sixteen hours; atmospheric features move at different rates.
Neptune needs about 165 Earth years to orbit the Sun. Its interior releases heat and contains a larger proportion of heavy compounds than the gas giants.
Rings & moons
Neptune has faint rings. Its largest moon, Triton, orbits in the opposite direction to the planet’s rotation, supporting a captured-origin interpretation.
Its largest moon follows a retrograde orbit and is thought to be a captured Kuiper Belt object. This view focuses on Neptune itself.
Exploration
Voyager 2 passed Neptune in 1989. Telescopic observations continue to track its weather, rings and moons.
Read the detailed records
Open the full exhibit Codex for individual structure records and time-specific information. The Credits page lists source creators, licenses and adaptations.