Moons · Moon of Neptune
Triton
4.5 billion km from the Sun · Light crosses it in 0.0090 seconds
- Across
- 2,707 km
- Vs Earth
- 0.21× Earth
- Mass
- 0.36% of Earth
About
Triton orbits Neptune backwards, which almost certainly means it did not form there: it is a captured object from the Kuiper Belt, seized by Neptune's gravity. Voyager 2 flew past in 1989 and found nitrogen geysers erupting from one of the coldest surfaces ever measured.
Orbits backwards, a sign it was a captured Kuiper Belt object.
At a glance
| Orbits | Neptune, backwards, every 5.9 days |
|---|---|
| Surface | −235 °C |
| Atmosphere | Thin nitrogen |
| Discovered | 1846, 17 days after Neptune |
Did you know
- Its retrograde orbit is slowly decaying; in a few billion years Neptune's tides will tear it into a ring.
- Geysers throw nitrogen gas and dust 8 km up, where winds smear them into dark streaks.
- Only about 40% of its surface was mapped by Voyager 2. No spacecraft has been back.
Real photo
- Triton from Voyager 2, 1989 — NASA/JPL/USGS · source