Moons are known to have different temperatures as compared to the main planets. In the case of Triton, this is known to be as cold as Pluto at 34.5 K (-235 C, -391 F). It is not possible for any human being to be able to withstand this type of temperature. The moon does not get enough light from the sun probably because of its distance.
It also has a thin atmosphere which is not able to absorb enough sunlight to make this work. There are different elements that can be found in the solar system that will also freeze upon reaching the surface of Triton such as carbon dioxide and methane. Some say that Triton has to be the coldest place in the solar system right now.