Triton Moon Facts

Triton is Neptune’s largest moon and was discovered in 1846 by William Lassell, a British astronomer, just 17 days after Alexis Bouvard, a French astronomer, discovered Neptune.

Triton Moon Profile

Discovered By:William Lassell October 10, 1846
Diameter:2,706.8 km
Mass:2.14 × 10^22 kg (29.1% Moon)
Orbit Distance:354,759 km
Orbit Period:5.9 days (retrograde)
Surface Temperature:-135 °C

Up until 1949, Triton was just referred to as a satellite of Neptune.

Once found, scientists have been studying it for many years because it seems to have some odd characteristics, including the fact that it’s the only moon in our solar system that has an orbit that is opposite of its parent planet’s rotation.

Moon Names

All of the moons of Neptune are named after mythological Greek or Roman characters that were associated with Neptune, Poseidon, or the oceans.

Spacecraft Missions

The two Voyager probes that were sent out in 1977 allowed them to flyby Neptune and its moons. Scientists found that Triton has a very strange surface with both cratered and smooth plains sitting next to each other.

The flyby also allowed scientists to see that Triton very likely has some form of ice volcanism as, according to NASA, Voyager 2 found “several geyser-like volcanic vents that were apparently spewing nitrogen gas laced with extremely fine, dark particles.”

They also believe that both Triton and Pluto might share a history that is similar as they are both almost the same size and have atmospheres that contain nitrogen and icy surfaces.

The New Horizon spacecraft flew by Triton in 2014, releasing some of the highest resolution maps ever seen.

The Voyager 2 mission continued to show unusual characteristics on Triton.

Triton fascinates scientists

The scientists found large portions of Triton’s surface that seemed to be melting, and it is believed that this is due to the tidal heating caused when the planet Neptune first captured Triton.

Triton fascinates scientists and although there aren’t any new space missions planned, computer models of the Neptune have given some additional insights.

Using the Voyager 2 information they believe that Neptune’s magnetosphere seems to be more pronounced on one side and they are curious as to how this affects Triton.

Facts about Triton

  • The European Southern Observatory’s Very Large Telescope has also discovered that Triton’s very thin atmosphere has a seasonal change.
  • Scientists have stepped up their game for the study of Triton by studying other celestial bodies in the solar system that could be interrelated with Triton.
  • Studying the surface of comets that contain nitrogen is helping them to compare where nitrogen came from on bodies such as Pluto and Triton.
  • The astrobiologists that have been spending a lot of time studying Triton seem to think that there is a good chance that Triton may have an ocean below its surface that contains a high percentage of ammonia.
  • Scientists are also guessing at the size of Triton’s rocky core. Without knowing the size they can’t figure out how much it heats the interior that would create under surface oceans.
  • Trying to decide how Triton became one of Neptune’s moons is something that scientists love to think about.
  • In 2006 scientists published a model that said that Triton might have been part of a binary system that orbited our own sun and that when it got close to Neptune, the planet snagged it and pulled it closer with its gravity, letting its sister body escape.
  • These scientists think that the survival of Triton is only due to Neptune capturing and saving it. In this model the writers believe that Triton then played an important function in creating Neptune’s system, including throwing some of the previous moons into Neptune or out of orbit.
  • One of the observations that validates some of this theory is that there has been chaos in the Neptune system which includes oddly stretched-out orbits of some of its moons.


  • In comparison of size, what distinction does Triton have as one of Neptune’s moons?
    it’s the largest
  • What 2 NASA probes did flybys that discovered a lot of information about Triton?
    Voyager 1 and Voyager 2
  • What is different about Triton’s rotation around Neptune than any other moon in our solar system?
    Triton rotates in the opposite direction of Neptune
  • What other celestial bodies are scientists studying to help them understand Triton?
  • What other celestial body might share the same history as Triton due to size, atmosphere and surface?
  • What question about Triton’s core hasn’t been answered that would affect information about the creation of water under its surface?