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Moons of Neptune

The capture of Triton

 Automatic translationAutomatic translation Category: moons
Updated July 20, 2013

Neptune is the eighth and last planet, the most distant solar system to 4.498 253 billion km.
Reaches of our solar system we find Neptune, the planet gas giant and ice, almost 4 times larger than Earth with a diameter of 49 922 km.
Neptune orbits the Sun in 164 years 323 days 21.7 hours and the day is 16H 6.6 min.
Its atmosphere is windswept fastest in the solar system (up to 1600 km/h) but its winds of hydrogen, helium and methane are so light they would not turn a land wind. However, giant storms developed there.
The moons of Neptune system is complex, some moons may be of extra-solar. Indeed Neptune's moons to draw from the material beyond the orbit of Pluto, probably in the Kuiper Belt where many objects revolve. Occasionally objects collide and are projected through the solar system, some of these icy bodies are transformed into comets but others may be attracted by a giant planet and become one of its moons.
This is what scientists envision for Triton.
The orbit of Triton reversed relative to the rotation of Neptune and its characteristics suggest it belonged to the Kuiper belt and it is not an isolated case.
For example, the outer moons of Jupiter, Ananke, Carme, Pasiphae and Sinope and those of Saturn, Phoebe also have a retrograde orbit, but all are less than 10% of the diameter of Triton.


Triton's largest moon of Neptune, is the coldest object (-198°C) in the Solar System, colder than Pluto which it resembles.
At this temperature the nitrogen should be in a gaseous state, it forms a golden dome ice at both poles of the moon. Its surface reflects approximately 70% of the light as it absorbs little light it is very cold.
Plumes cryovolcanism on its surface, captured by the Voyager spacecraft, are fascinating, they spit a mixture of liquid nitrogen, methane and ammonia.
The probe shows a complex and active.
The dark streaks on the picture cons seem to come from small volcanoes and consist of nitrogen frost mixed with organic compounds ejected by geysers of Triton.
In the light atmosphere of Triton, these eruptions immediately freeze and ice falls of snow. Traveling with the first quick overview of Triton gave us much information but not enough for scientists.
Triton is a moon very interesting because it can potentially contain water and thus traces of life.

 geysers of Triton, Neptune's moon

Image: This image of Triton taken by Voyager 2 in 1989, shows us a fascinating field, a thin atmosphere and even ice volcanoes. In August 1989 Voyager 2 flies over Neptune, the farthest of the giant planets of the solar system. Its closest approach to Triton was made at a distance of about 24000 miles or 38624 kilometers.

The moons of Neptune


- Naiad (N III Naiad) is the closest moon of Neptune, discovered in 1989 by Voyager 2.
- Thalassa (N IV Thalassa) is the second moon of Neptune, discovered in 1989 by Voyager 2.
- Despina (NV Despina) is the third moon of Neptune, discovered in 1989 by Voyager 2.
- Galatea (Galatea VI N) is the fourth moon of Neptune, discovered in 1989 by Voyager 2.
- Larissa (Larissa N VII) is the fifth moon of Neptune, discovered by Harold J. Reitsema, William B. Hubbard, Larry A. Lebofsky and David J. Tholen at a star occultation by Neptune May 24, 1981.
- Proteus (Proteus VIII N) is the sixth moon of Neptune, discovered in 1989 by Stephen P. Synnott and Bradford A. Smith.
- Triton (Triton NI) is the seventh and largest moon of Neptune, discovered in 1846, just 17 days after Neptune by William Lassell.
- Nereid (N II Nereid) is the eighth moon of Neptune, discovered in 1949 by Gerard Kuiper.
- Halimeda is the ninth moon of Neptune, discovered in 2002 by the team of Matthew J. Holman.
- Sao is the tenth moon of Neptune, discovered in 2002 by the team of Matthew J. Holman.
- Laomedeia is the eleventh moon of Neptune, discovered in 2002 by the team of Matthew J. Holman.
- Psamathe is the twelfth moon of Neptune, discovered by the team of Scott S. Sheppard.


- Neso is the thirteenth moon of Neptune and the later discovered by the team of Matthew J. Holman.
- S/2004 N 1 is the fourteenth moon of Neptune, which orbits the planet in a little less than one earth day.

Moons of
axis (km)
Triton ≈2 706 354 759
Proteus ≈420 117 646
Nereid ≈340 5 513 818
Larissa ≈194 73 548
Galatea ≈176 61 953
Despina ≈150 52 526
Thalassa ≈82 50 074
Naiad ≈66 48 227
Halimede ≈62 16 611 000
Neso ≈60 49 285 000
Sao ≈44 22 228 000
Laomedia ≈42 23 567 000
Psamathe ≈40 48 096 000
S/2004 N1 ≈18 105 283
 Neptune, Proteus, Larissa, Galatea and Despina

Image: Neptune captured by the Hubble Space Telescope, this image is surrounded on four of its satellites, Proteus (top), Larissa (leftmost), Despina (left below Larissa) and Galatea (bottom) of image.

The fourteenth moon of Neptune

Since 1989 (Voyager 2) it was thought that Neptune was only 13 moons. S/2004 N 1 is the provisional designation of the fourteenth moon of Neptune, with reference to 2004 as the moon appears in the images captured by the Hubble Space Telescope between 2004 and 2009. It orbit around Neptune in a little less than one earth day (23H). Astronomers have discovered it, the first in July 2013 in 150 pictures selected for their work, following a white dot which appeared regularly in these photos. These images have long been accessible to the public, which means that the discovery could have been made by anyone, but it is an astronomer Mark Showalter of the SETI Institute, which saw by chance the new moon. It was thought that Voyager 2 had observed all the inner satellites of Neptune during the flyover of the planet in 1989, but the small S/2004 N 1 was not appeared on any photography. This is not surprising because the small moon is very dark. In the picture you can see against outside the retrograde and inclined orbit of the largest moon of Neptune, Triton. It is assumed that Neptune captured Triton from the Kuiper belt, long after the formation of the original satellite system of Neptune. The orbits of the original moons were disturbed by this cosmic event, which led to the ejection of a few moons and destruction by collision other moons. S/2004 N 1 is well within of the original system of satellites, since it resembles other inner satellites of Neptune with the colors of asphalt. Albedo has given him a diameter of 16-20 km, making it the smallest known moons of Neptune in 2013. The spectral data are insufficient to identify the molecules present on the surface, but the water ice is abundant in the outer solar system, is assumed to be present on S/2004 N 1, although its spectral signature is not observed.
The future name of this moon of Neptune will conform to the names of figures from Greek and Roman mythology in connection with Poseidon / Neptune, the god of the sea.

Image: Diagram of the orbits of inner moons of Neptune until the eighth orbit, that of, Triton. The sixth inner orbit is that of S/2004 N 1 the fourteenth moon of Neptune discovered on July 1, 2013 on the Hubble Space Telescope images taken in 2004.

 Orbits of the moons of Neptune

See also

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