Triton is the largest moon of the planet Neptune, discovered on October 10, 1846, by English astronomer William Lassell. It is the only large moon in the Solar System with a retrograde orbit, which is 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 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 grams per cubic centimetre (0.0745 lb/cu in) 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 a complex geological history revealed in intricate and mysterious cryovolcanic and tectonic terrains. Part of its crust is dotted with geysers thought to erupt nitrogen. Triton has a tenuous nitrogen atmosphere less than 1/70,000 the pressure of Earth’s atmosphere at sea level.
Triton was proposed as the final colony during the expansion phase of the USH, it has also been the most difficult. Early adopters of Triton saw the planet as an attempt to get away from USH theological ideals, openly using genetic research. The USH stepped in and the conflict that pursued lasted 4 years until finally an overwhelming armada from Uranus Station came in threatening to destroy the entire colony. In the time since there is still a strong resistance on Triton, but no outward defiance against USH.
Triton has a strong Patrol presence in the colony. The Patrol monitors all Darkgate traffic in orbit around Triton.