Triton may be one of the largest of the icy moons, is comparable to Europa, with a diameter of 2700 km (1800 miles). 1800 miles is about half the distance across the United States.

Triton is very interesting, it has a unique and fascinating surface, and is one of the few moons with the possibility for a weak atmosphere and an environment suitable for life. Triton is also unusual for its retrograde orbit. Because Voyager 2 did not pass very close to Triton, it was not determined whether Triton is composed completely of ice, or is a rocky moon with an icy surface.