Neptune · natural satellite

Triton

A large moon on a retrograde orbit

Triton travels around Neptune opposite the planet’s rotation. Voyager 2 observed a nitrogen-rich surface and active dark plumes during its 1989 flyby.

Mean diameter: 2,705.2 km
Mean orbital distance: 354,800 km from centre
Orbital period: 5.879 Earth days

Triton · NASA spacecraft imagery — NASA/JPL · Image source ↗

Compared with our Moon

Triton · 2,705.2 km

Moon · 3,474.8 km

One diameter scale. Circle shapes compare volume-equivalent diameters; irregular moons are not spheres.

Orbit & discovery

Surface gravity: 0.781 m/s²
Discovery: 1846
Discoverer / team: W. Lassell
Provisional designation: —
JPL satellite ID: 801
Orbital eccentricity: 0
Inclination: 157.3 degrees

Inclination reference: equatorial. Mean-element epoch: 2000-01-01.5 TDB · NEP098.

Diameters use volume-equivalent mean radii, including for irregular bodies. Mean orbital elements describe an orbit; they are not live positions. Missing physical measurements remain unavailable.

Physical measurements & uncertainties

Mean radius · km: 1352.60 ±2.40 [1]
GM · km³/s²: 1428.49546 ±0.61603 [NEP097]
Density · g/cm³: 2.0649 ±0.0110 [*]

Missions in the Neptune system · 1 records

1 launches · 0 linked events

These records cover the planetary system. A system mission did not necessarily visit this moon. Dedicated targets are marked separately; programme events include the journey and briefings. Launch outcomes do not establish arrival, landing success or present spacecraft operation.

Dedicated targets only

PLANETARY SYSTEM

Voyager 2

August 20, 1977 · UTC

Lockheed Martin · Titan IIIE

1 records from the complete 9,386‑record production catalogue.

Sources & measurements