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Moons of Neptune facts for kids

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New Webb Images Capture Rare View of Neptune’s Rings (Labeled)
An annotated picture of some of Neptune's many moons as captured by the James Webb Space Telescope. The bright blue diffraction star is Triton, Neptune's largest moon; while Hippocamp, its smallest regular moon, is too small to be seen.

The planet Neptune has 16 known moons. They are named after water gods and creatures from ancient Greek stories. The biggest moon is Triton. It was found by William Lassell in 1846, just 17 days after Neptune was discovered!

It took over 100 years to find the second moon, Nereid, in 1949. Then, 40 more years passed before Proteus was found in 1989. Proteus is Neptune's second largest moon.

Neptune's moons are split into two main groups: regular and irregular. The regular moons are the seven inner moons. They travel in nearly perfect circles around Neptune's middle. The other nine moons, including Triton, are irregular. They usually have tilted and stretched-out paths far from Neptune. Triton is special because it orbits close to Neptune, but its path is backward and tilted.

Neptune's Moons: A Closer Look

Here is a list of Neptune's moons. They are ordered from the fastest to the slowest in their orbits around Neptune. Moons that are "irregular" (meaning they were likely captured by Neptune's gravity) are shown with a colored background.

The paths of irregular moons can change a lot. This is because of the pull from Neptune and the Sun. So, the orbital details for these moons are averages over a very long time. Triton is the only moon big enough to be perfectly round. Its name is in bold below.


Neptune's Moons
Number Name Image Size
(km)		 Distance from Neptune
(km)		 Orbital Period
(days)		 Discovery
Year		 Discoverer Group
III Naiad
A smeared white object elongated from the bottom-left to top-right can be seen in the center.
 60 48224 +0.2944 1989 Voyager Science Team inner
IV Thalassa
A group of three objects, each circled and labeled by the respective designations. Thalassa is the central object designated 1989 N5.
 81 50074 +0.3115 1989 Voyager Science Team inner
V Despina
A white oval shaped object somewhat elongated horizontally is seen in the center. There are a few small dark spots on its surface.
 156 52526 +0.3346 1989 Voyager Science Team inner
VI Galatea
A small white object elongated from the bottom-left to top-right can be seen in the center.
 175 61953 +0.4287 1989 Voyager Science Team inner
VII Larissa
An irregularly shaped grey object slightly elongated horizontally occupies almost the whole image. Its surface shows a number of dark and white spots.
 194 73548 +0.5555 1981 Reitsema et al. inner
XIV Hippocamp
Composite of multiple Hubble images of the Neptune system, with the moons appearing as bright white dots. The fainter dot to the upper right is Hippocamp, circled and labeled to distinguish it from other moons in this image.
 35 105283 +0.9500 2013 Showalter et al. inner
VIII Proteus
A conically shaped object is seen almost fully illuminated from the left. The cone axis looks towards the observer. The outline of the object is a rectangle with rounded corners. The surface is rough with a few large depressions.
 420 117646 +1.1223 1989 Voyager Science Team inner
I Triton
A large spherical object is half-illuminated from the bottom-left. The south pole faces to the light source. Around it in the bottom-left part of the body there is a large white area with a few dozens dark streaks elongated in the pole to equator direction. This polar cap has a slight red tinge. The equatorial region is darker with a tint of cyan. Its surface is rough with a number of craters and intersecting lineaments.
 2705 354759 −5.8769 1846 Lassell Irregular
II Nereid
A small white smeared body is seen in center.
 357 5504000 +360.14 1949 Kuiper Irregular
IX Halimede
N2002n1b.jpg
 62 16590100 −1879.30 2002 Holman et al. Irregular
XI Sao
Sao VLT-FORS1 2002-09-03 annotated.gif
 44 22239300 +2918.70 2002 Holman et al. Sao Group
S/2002 N 5 38 23365200 +3141.26 2002 Holman et al. Sao Group
XII Laomedeia
Laomedeia VLT-FORS1 2002-09-03.gif
 42 23502300 +3175.65 2002 Holman et al. Sao Group
X Psamathe
Psamathe arrow.png
 40 47611900 −9149.87 2003 Sheppard et al. Neso Group
XIII Neso
Neso VLT-FORS1 2002-09-03.gif
 60 49871600 −9796.67 2002 Holman et al. Neso Group
S/2021 N 1 25 50623600 −10017.93 2021 Sheppard et al. Neso Group

Images for kids

  • Orbits of inner moons of Neptune including S 2004 N 1

    Orbit diagram of Neptune's inner moons including Triton, with their names and orbit directions indicated

  • Neptune inner moons size comparison

    Size comparison of Neptune's seven inner moons

  • Neptunemoonsdiagram

    Orbital diagram of the orbital inclination and orbital distances for Neptune's rings and moon system at various scales. Notable moons and rings are individually labeled. Open the image for full resolution.

See also

Kids robot.svg In Spanish: Satélites de Neptuno para niños

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