Triton (moon)
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Voyager 2 photomosaic of Triton
|
|
| Discovery | |
|---|---|
| Discovered by | William Lassell |
| Discovery date | October 10, 1846 |
| Designations | |
| Pronunciation | /ˈtraɪtən/ |
| Neptune I | |
| Adjectives | Tritonian |
| Orbital characteristics | |
| 354759 km | |
| Eccentricity | 0.000016 |
|
−5.876854 d (retrograde) |
|
|
Average orbital speed
|
4.39 km/s |
| Inclination | 129.812° (to the ecliptic) 156.885° (to Neptune's equator) 129.608° (to Neptune's orbit) |
| Satellite of | Neptune |
| Physical characteristics | |
|
Mean radius
|
1353.4±0.9 km (0.2122 Earths) |
| 23018000 km2 | |
| Volume | 10384000000 km3 |
| Mass | 2.14×1022 kg (0.00359 Earths) |
|
Mean density
|
2.061 g/cm3 |
| 0.779 m/s2 (0.0794 g) (0.48 Moons) | |
| 1.455 km/s | |
| synchronous | |
|
Sidereal rotation period
|
5 d, 21 h, 2 min, 53 s |
| 0 | |
| Albedo | 0.76 |
| Temperature | 38 K (−235.2 °C) |
| 13.47 | |
| −1.2 | |
| Atmosphere | |
|
Surface pressure
|
1.4–1.9 Pa (1/70000 the surface pressure on Earth) |
| Composition by volume | nitrogen; methane traces. |
Triton is the largest natural satellite of the planet Neptune. It was discovered on October 10, 1846, by English astronomer William Lassell. It is the only large moon in the Solar System with a retrograde orbit, an orbit in the opposite direction to its planet's rotation. At 2,700 kilometres (1,700 mi) in diameter, it is the seventh-largest moon in the Solar System. Because of its retrograde orbit and composition similar to Pluto's, Triton is thought to have been a dwarf planet captured from the Kuiper belt. Triton has a surface of mostly frozen nitrogen, a mostly water-ice crust, an icy mantle and a substantial core of rock and metal. The core makes up two-thirds of its total mass. Triton has a mean density of 2.061 g/cm3 and is composed of approximately 15–35% water ice.
Triton is one of the few moons in the Solar System known to be geologically active. As a consequence, its surface is relatively young with sparse impact craters, and a complex geological history revealed in intricate cryovolcanic and tectonic terrains. Part of its surface has geysers erupting sublimated nitrogen gas, contributing to a tenuous nitrogen atmosphere less than 1/70,000 the pressure of Earth's atmosphere at sea level.
Triton was discovered by British astronomer William Lassell on October 10, 1846, just 17 days after the discovery of Neptune.
A brewer by trade, Lassell began making mirrors for his amateur telescope in 1820. When John Herschel received news of Neptune's discovery, he wrote to Lassell suggesting he search for possible moons. Lassell did so and discovered Triton eight days later. Lassell also claimed to have discovered rings. Although Neptune was later confirmed to have rings, they are so faint and dark that it is doubtful that he actually saw them.
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