Triton
Triton
Moon of Neptune
Triton facts
- Orbits
- Neptune
- Distance from Neptune
- 354,759 km (14.4 Neptune-radii)
- Orbital period
- 5.9 days (retrograde)
- Diameter
- 2,707 km
- Mass
- 2.14 × 10²² kg
- Orbital inclination
- 156.87°
- Tidally locked
- Yes
- Discovered
- 1846, by William Lassell
Triton orbits Neptune
Watch Triton (highlighted) circle Neptune. Press play; the moons run at their real relative speeds.
Relative sizes and spacing are compressed; orbits shown coplanar. Click a moon for its page.
Paused
About Triton
Triton is Neptune's largest moon and the only large moon that orbits backward (retrograde), which strongly suggests it is a captured Kuiper Belt object. It is one of the coldest places in the Solar System, yet Voyager 2 saw active nitrogen geysers erupting from its icy surface.
- Named after a sea god, son of Poseidon in Greek myth
- Discovered: 1846, by William Lassell
Triton: frequently asked questions
- What is Triton?
- Triton is Neptune's largest moon and the only large moon that orbits backward (retrograde), which strongly suggests it is a captured Kuiper Belt object.
- What planet does Triton orbit?
- Triton orbits Neptune at an average distance of about 354,759 km, completing one lap every 5.9 days.
- How big is Triton?
- Triton has a diameter of about 2,707 km and a mass of roughly 2.14 × 10²² kg.
- Why is Triton famous?
- Triton's claim to fame: the only large moon in the Solar System with a retrograde orbit, revolving backward relative to Neptune's spin.
- Why does Triton orbit backward?
- Triton orbits Neptune retrograde, opposite to the planet's spin. That is strong evidence it did not form alongside Neptune but was captured later, likely from the Kuiper Belt.
See Triton in motion
Back to Neptune, or open the full Solar System orrery →
Data from NASA/JPL and NSSDCA. Source.