Triton Facts

Triton is the largest moon of the planet Neptune, the seventh-largest moon in the solar system, and the 16th largest object in the solar. It is composed of frozen nitrogen.

Triton Profile

Interesting Triton Facts

  1. Triton was discovered by William Lassell in 1846.
  2. Triton has been named after the son of Poseidon.
  3. It is the largest moon of Neptune.
  4. Triton has a radius of 2,710 km.
  5. Triton is mostly composed of frozen Nitrogen.
  6. Triton has a reddish appearance.
  7. Triton has a relatively young surface.
  8. Triton revolves around Neptune in 5.87 days at the speed of 4.4 km per second.
  9. Triton reflects back 60 to 90% of the light that it receives from the sun.
  10.  It has a well differentiated internal structure.
  11. It has been visited by the space craft Voyager 2 by NASA.


The moon Triton was discovered by the British astronomer William Lassell in 1846. This discovery took place only 17 days after the discovery of its parent planet of Neptune. William Lassell was inspired to search for a Neptunian moon by John Herschel when he got the news of Neptune’s discovery. Lassell spotted the moon with the help of a telescope of his own making.

The name Triton comes from Greek mythology. It was the name of the Greek sea god and son of Poseidon. This name was suggested by Camille Flammarion in one of his books. However, it was accepted many decades later.


Triton has a radius of 2,710 km. This makes it the largest moon of the planet Neptune, the seventh-largest moon in the solar system, and the 16th largest object in the solar system overall. Its diameter is 5.5 % of that of Neptune.

Triton weighs 2.14 × 10^22 kg which makes it about 29.1% of Earth’s moon in weight.

This makes it the largest moon of a gaseous planet relative to the size of the parent, in terms of diameter. Triton comprises nearly 99.5% of the total mass of all the objects that revolve around Neptune including the rings. The moon is also a bit larger than the dwarf planets Eris and Pluto.


Triton has a reddish appearance, which may be a result of methane ice being exposed to the sun’s ultraviolet radiation over the years. Also, there are very few craters visible on its surface. This indicates that the surface is relatively young.

Surface and Composition

The surface of Triton is covered by a thin sheet of frozen nitrogen. The crust consists of nearly 55% of nitrogen with other ices such as frozen carbon dioxide.

The presence of traces of ammonia is also suggested as the lithosphere is known to contain ammonia, dihydrate. Only 40% of the surface of the moon has been observed.

However, scientists believe that the remaining remainder has similar surface compositions. As mentioned before, Triton’s surface is believed to be young, considering the fact that the surface has very few impact craters. 

The surface is highly reflective. Triton has an unusually large albedo. It reflects back about 60 to 95% of the sunlight that it receives.

Triton is also believed to be well differentiated into a crust, a mantle, and a solid core. The core is believed to be constructed of rock and metal while the mantle primarily consists of water.

The amount of rock contained in the interior of Triton is sufficient to support radioactive decay which maintains a subsurface ocean. This phenomenon exists in the case of several other objects in the solar system such as the moon Europa.

Magnetic Field

The moon Triton is believed to possess no or a weak magnetic field of its own.

Orbit and Rotation

Triton takes approximately 5.87 days to revolve around Neptune with an orbital speed of close to 4.4 km per second.

The moon Triton orbits around Neptune in a direction opposite to the rotation of its parent planet. This is known as a retrograde orbit. In this case, Triton is a unique astronomical body.

Most of the other moons that display this characteristic are irregular and much smaller in size as compared to Triton. Triton is tidally locked to Neptune. This means that it always has one face pointing towards the planet.


Triton is known to have a very thin atmosphere mostly composed of nitrogen with some traces of carbon monoxide and methane near its surface. It is believed to have been formed due to the evaporation of nitrogen from the surface.

A similar phenomenon is responsible for the formation of Pluto’s atmosphere. The atmospheric pressure on the surface of Triton is about 1.4 to 1m9 Pa. Till about an altitude of 8 kilometers a layer called the troposphere exists.

There is no stratosphere. However, Triton does have a thermosphere that stretches from an altitude of 8 km to 950 km.


Until the flyby conducted by the Voyager 2 spacecraft, Triton had only been observed through telescopes. Thus, most of the details about the moon were previously unknown. However, by the 19th century, most of the orbital properties of Triton had already been studied.

Gerard Kuiper tried to estimate the diameter of Triton in 1954 but failed to obtain accurate results. After the flyby of Voyager 2, the possible presence of liquid nitrogen seas and an atmosphere on Triton was suggested.

Various missions to Neptune and its moon system have been proposed but none of them have been approved so far. Triton has obviously also never been visited by human beings due to reasons of extreme temperature and pressure conditions.

However, scientists are making continuous efforts to explore the moons of different planets in more detail.

Potential for Life

No evidence of life has ever been found on Triton. This is due to the extreme temperature and pressure conditions. If any life does exist on the moon, it would be very different from that on the Earth. The possibility of finding life forms elsewhere in the universe can never be ruled out.

Pop Culture

People continue to be fascinated by the planets in the solar system as well as their moons. Triton has been mentioned in several elements of pop culture such as films, television shows, books, video games, etc, either individually, or collectively as a part of the Neptunian moon system.


  • 1846: Triton is discovered
  • 1989: Voyager 2 conducts a flyby of the moon


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