This photo, taken by NASA through green, violet and ultraviolet filters, shows the bright southern hemisphere of Triton. Triton is named after the Greek sea god Triton, the son of Poseidon (the Greek god comparable to the Roman Neptune). Triton is the only Neptune moon that has an internal geology; it is known to have geological activity like geysers and volcanic activity. It is one of very few such moons in the solar system. Experts believe that Triton could have been a captured object from the nearby Kuiper Belt, where the dwarf planet Pluto and other objects reside. Triton is the largest of Neptune's moons and the only object that orbits any planet in a retrograde orbit. Just like our own moon, it is locked in a synchronous rotation with its home planet.