The term Neptune Satellite refers to the moon TRITON, which orbits the planet Neptune. TRITON is the largest of Neptune's 14 known moons and is the only one with a retrograde orbit, meaning it orbits in the opposite direction of Neptune's rotation. It is also the only large moon in the Solar System with a retrograde orbit. TRITON was discovered in 1846 by British astronomer William Lassell and is named after the Greek god of the sea, TRITON.