Hugo's Solar SystemHome › Explore › Neptune › How many moons?
Moon count, as of September 2026
How many moons does Neptune have?
16 known moons.
Neptune has 16 known moons as of September 2026, according to NASA and the JPL Solar System Dynamics group. The 14 largest are listed below; the other 2 are small moons, most only a few kilometres across and found since 2000, and many do not yet have names.
The named moons
Sorted by size. Distance is the average distance from the centre of Neptune.
| Moon | Diameter (miles / km) | Distance (miles / km) | One orbit | Discovered |
|---|---|---|---|---|
| Triton | 1,680 / 2,707 | 220,000 / 354,759 | 5.877 days | 1846, William Lassell |
| Proteus | 261 / 420 | 73,100 / 117,647 | 1.122 days | 1989, Voyager 2 |
| Nereid | 222 / 357 | 3,430,000 / 5,513,818 | 1.0 years | 1949, Gerard Kuiper |
| Larissa | 121 / 194 | 45,700 / 73,548 | 13 hours | 1981 from Earth, confirmed by Voyager 2 in 1989 |
| Galatea | 109 / 176 | 38,500 / 61,953 | 10 hours | 1989, Voyager 2 |
| Despina | 93.2 / 150 | 32,600 / 52,526 | 8 hours | 1989, Voyager 2 |
| Thalassa | 51 / 82 | 31,100 / 50,075 | 7 hours | 1989, Voyager 2 |
| Halimede | 38.5 / 62 | 10,300,000 / 16,611,000 | 5.1 years | 2002, Matthew Holman and team |
| Neso | 37.3 / 60 | 30,600,000 / 49,285,000 | 25.7 years | 2002, Matthew Holman and team |
| Naiad | 37.3 / 60 | 30,000 / 48,227 | 7 hours | 1989, Voyager 2 |
| Sao | 27.3 / 44 | 13,800,000 / 22,228,000 | 8.0 years | 2002, Matthew Holman and team |
| Laomedeia | 26.1 / 42 | 14,600,000 / 23,567,000 | 8.7 years | 2002, Matthew Holman and team |
| Psamathe | 24.9 / 40 | 29,000,000 / 46,695,000 | 25.0 years | 2003, Scott Sheppard and team |
| Hippocamp | 21.7 / 35 | 65,400 / 105,283 | 23 hours | 2013, Mark Showalter, in Hubble images |
Why the number keeps changing
Big moons were found centuries ago through telescopes. The small ones, often only a few kilometres across, are found today by long camera exposures on the largest telescopes and by spacecraft. Each new batch is announced by the Minor Planet Center, so the count goes up in jumps. That is why every count on this site carries a date.