Neptune has thirteen known moons. Naiad, Thalassa, Despina, Galatea, Larissa, Proteus, Triton, Nereid, S/2002 N1, S/2002 N2, S/2002 N3, S/2002 N4, and S/2003 N1.
The first four moons orbit within Neptune’s ring system. Proteus is Neptune’s second-largest moon and lies so close to the planet that Earth-bound telescope cannot detect it. Triton is one of the three moons in our system that has an atmosphere and has a retrograde orbit. Nereid has a highly elliptical orbit causing it to have varying distances from Neptune.