Neptunian Satellite Fact Sheet


Triton and Neptune
Bulk parameters
  Mass
(1020 kg)
Radius
(km)
Mean density
(kg/m3)
Visual
geometric albedo
   
Naiad (NIII) 0.002 48 x 30 x 26   0.07
Thalassa (NIV) 0.004 54 x 50 x 26   0.09
Despina (NV) 0.02 90 x 74 x 64   0.09
Galatea (NVI) 0.04 102 x 92 x 72   0.08
Larissa (NVII) 0.05 108 x 102 x 84   0.09
S/2004 N1 0.00005 10   0.10
Proteus (NVIII) 0.5 220 x 208 x 202   0.10
Triton (NI) 214. 1,353.4 2,050 0.72
Nereid (NII) 0.3 170   0.16
   
Halimede (NIX, S/2002 N1) 0.002 30   0.04
Sao (NXI, S/2002 N2 0.001 20   0.04
Laomedeia (NXII, S/2002 N3) 0.001 20   0.04
Neso (NXIII, S/2002 N4) 0.002 30   0.04
Psamathe (NX, S/2003 N1) 0.0002 20   0.04

Orbital parameters
  Semi-major
axis
(103km)
Semi-major
axis
(Neptunian Radii)
Orbital
Period*
(days)
Rotation
Period
(days)
Inclination
(degrees)
Eccentricity
   
Naiad (NIII) 48.227 1.948 0.294396   4.74 0.0003
Thalassa (NIV) 50.075 2.022 0.311485   0.21 0.0002
Despina (NV) 52.526 2.121 0.334655   0.07 0.0001
Galatea (NVI) 61.953 2.502 0.428745   0.05 0.0001
Larissa (NVII) 73.548 2.970 0.554654   0.20 0.0014
S/2004 N1 105.300 4.252 0.950   0.00 0.0000
Proteus (NVIII) 117.647 4.751 1.122315   0.04 0.0004
Triton (NI) 354.76 14.328 5.876854R S 157.345 0.000016
Nereid (NII) 5,513.4 222.67 360.13619   7.23 0.7512
   
Halimede (NIX, S/2002 N1) 15730. 635.2 1879.7R   134.1 0.571
Sao (NXI, S/2002 N2 22420. 905.3 2914.1   48.5 0.293
Laomedeia (NXII, S/2002 N3) 23570. 951.8 3167.9   34.7 0.424
Psamathe (NX, S/2003 N1) 46700. 1885.8 9115.9R   137.4 0.450
Neso (NXIII, S/2002 N4) 48390. 1954.0 9374.0R   132.6 0.495

*R indicates retrograde motion
S indicates synchronous rotation - the rotation period is the same as the orbital period


Neptune's Known Satellites - Carnegie Institution, DTM

Neptune Fact Sheet
Neptune Home Page
Notes on the Factsheets
Directory to other Planetary Fact Sheets


NASA
Author/Curator:
Dr. David R. Williams, dave.williams@nasa.gov
NSSDCA, Mail Code 690.1
NASA Goddard Space Flight Center
Greenbelt, MD 20771
+1-301-286-1258


NASA Official: Ed Grayzeck, edwin.j.grayzeck@nasa.gov
V1.0, 14 July 1995
Last Updated: 14 September 2016, DRW