Neptune’s moons
16 confirmed moons in this source snapshot.
| Moon | Mean radius · km | Semimajor axis · km | Period · days |
|---|---|---|---|
| Triton | Mean radius · km1,352.6 ± 2.4 | Orbit axis · km354,800 | Period · days5.87699 |
| ProteusS/1989 N 1 | Mean radius · km208 ± 8 | Orbit axis · km117,600 | Period · days1.12232 |
| Nereid | Mean radius · km170 ± 25 | Orbit axis · km5,513,900 | Period · days360.133 |
| LarissaS/1989 N 2 | Mean radius · km96 ± 7 | Orbit axis · km73,500 | Period · days0.554989 |
| GalateaS/1989 N 4 | Mean radius · km79 ± 12 | Orbit axis · km62,000 | Period · days0.428744 |
| DespinaS/1989 N 3 | Mean radius · km74 ± 10 | Orbit axis · km52,500 | Period · days0.334656 |
| ThalassaS/1989 N 5 | Mean radius · km40 ± 8 | Orbit axis · km50,100 | Period · days0.311078 |
| NaiadS/1989 N 6 | Mean radius · km29 ± 6 | Orbit axis · km48,200 | Period · days0.29398 |
| HalimedeS/2002 N 1 | Mean radius · km— | Orbit axis · km16,590,500 | Period · days1,879 |
| HippocampS/2004 N 1 | Mean radius · km— | Orbit axis · km105,300 | Period · days0.95039 |
| LaomedeiaS/2002 N 3 | Mean radius · km— | Orbit axis · km23,499,900 | Period · days3,168 |
| NesoS/2002 N 4 | Mean radius · km— | Orbit axis · km49,897,800 | Period · days9,805 |
| PsamatheS/2003 N 1 | Mean radius · km— | Orbit axis · km47,646,600 | Period · days9,149 |
| S/2002 N 5 | Mean radius · km— | Orbit axis · km23,414,700 | Period · days3,151 |
| S/2021 N 1 | Mean radius · km— | Orbit axis · km50,700,200 | Period · days10,043 |
| SaoS/2002 N 2 | Mean radius · km— | Orbit axis · km22,239,900 | Period · days2,919 |
Mean radii descend; missing radii follow. A dash means no value in these sources. Orbit summaries describe average shapes, and do not supply dated positions.