Correct Answer - Option 1 : 13
The correct answer is 13.
Planet Neptune has 13 known moons.
- In order of distance from Neptune, the regular moons are Naiad, Thalassa, Despina, Galatea, Larissa, Hippocamp, and Proteus.
- All but the outer two are within Neptune-synchronous orbit (Neptune's rotational period is 0.6713 days or 16 hours) and thus are being tidally decelerated.
Neptune has a total of 13 known moons.
The largest moon is Triton which was discovered by William Lassell just seventeen days after Neptune was found.
- One hundred years later the second moon, Nereid was found.