Unlike all other large planetary moons in the Solar System, Triton has a retrograde orbit, indicating that it was captured rather than forming in place; it was probably once a dwarf planet in the Kuiper belt.
Za razliku od drugih velikih satelita u Sunčevom sustavu, Triton ima retrogradnu orbitu što daje naslutiti da je zahvaćen, a ne formiran na mjestu; najvjerojatnije kao patuljasti planet iz Kuiperovog pojasa.