Space · Moons
Psamathe
A moon of Neptune — One of the most distant Neptunian moons — orbit takes 25 Earth years.
Quick facts
Parent planet
Diameter (mean)
40 km
Mass
4.9 × 10¹⁶ kg
6.7e-07 Moon masses
Mean orbital radius
46,695,000 km
Orbital period
9128.7 Earth days
Discovery year
2003
Discoverer
Scott S. Sheppard et al.
Naming origin
Nereid, mother of Phocus
Surface conditions
Psamathe is a retrograde outer irregular Neptunian moon with an extremely large orbit (46.7 million km, 25-year orbital period). Discovered in 2003 from Mauna Kea.
Missions and observations
Every Neptune-system mission has had an opportunity to image or characterize Psamathe. The list below is the Neptune-system mission catalog; specific Psamathe encounters are documented in mission archives.
| Mission | Year at Neptune | Status |
|---|---|---|
|
Voyager 2 NASA |
1989 | Completed |
Naming etymology
Psamathe was a Nereid sea nymph, mother of Phocus by Aeacus. Adopted by the IAU in 2007.
Methodology & sources
Diameter, mass, and orbital parameters from JPL Solar System Dynamics — Physical Parameters. Discovery year and discoverer from the JPL Satellite Discovery Circumstances. Naming etymology from the IAU Working Group for Planetary System Nomenclature. Stylized SVG hero composed from NASA / JPL imagery as visual reference; no photographs are reproduced.