![]() Neptune's irregular moons consist of the planet's remaining satellites (including Triton). In this respect, the inner Neptunian moons are similar to the inner moons of Uranus. Their spectra also indicated that they are made from water ice contaminated by some very dark material, probably organic compounds. In addition, all the inner moons dark objects, with geometric albedo ranging from 7 to 10%. Nevertheless, with the exception of Larissa and Proteus (which are largely rounded) all of Neptune's inner moons are believed to be elongated in shape. Only the two largest regular moons have been imaged with a resolution sufficient to discern their shapes and surface features. Meanwhile, Thalassa measures 108 x 100 × 52 km and weighs 3.5 x 10 17 kg Despina measures 180 x 148 x 128 and weighs 21 x 10 17 kg Galatea measures 204 x 184 x 144 and weighs 37.5 x 10 17 kg Larissa measures 216 x 204 x 168 and weighs 49.5 x 10 17 kg S/2004 N1 measures 16-20 km in diameter and weighs 0.5 ± 0.4 x 10 17 kg and Proteus measures 436 x 416 x 402 and weighs 50.35 x 10 17 kg. Showalter (SETI Institute).īased on observational data and assumed densities, Naiad measures 96 × 60 × 52 km and weighs approximately 1.9 x 10 17 kg. Hubble Space Telescope composite picture showing the location of a newly discovered moon, designated S/2004 N 1. The name Triton, which was originally suggested by Camille Flammarion in his 1880 book Astronomie Populaire, but not into common usage until at least the 1930s. However, many of the moons were not officially named until the 20th century. In this case, all are named for gods of the sea, or for the children of Poseidon (which include Triton, Proteus, Depsina and Thalassa), minor Greek water dieties (Naiad and Nereid) or Nereids, the water nymphs in Greek mythology (Halimede, Galatea, Neso, Sao, Laomedeia and Psamathe). In keeping with astronomical convention, Neptune's moons are all taken from Greek and Roman mythology. The as yet unnamed fourteenth moon, currently identified as S/2004 N 1, is thought to measure no more than 16–20 km in diameter. Showalter of the SETI Institute revealed that they had discovered a previously unknown fourteenth moon in images taken by the Hubble Space Telescope from 2004–2009. Follow-up surveys by two teams in 20 respectively re-observed all five of these moons – which were Halimede, Sao, Psamathe, Laomedeia, and Neso.Īnd then on July 15th, 2013, a team of astronomers led by Mark R. In 2001, two surveys using large ground-based telescopes – the Cerro Tololo Inter-American Observatory and the Canada-France-Hawaii telescopes – found five additional outer moons bringing the total to thirteen. In the course of passing through the system, the space probe rediscovered Larissa and discovered five additional inner moons: Naiad, Thalassa, Despina, Galatea and Proteus. No further moons were found until Voyager 2 flew by Neptune in 1989. This indicated the presence of a moon rather than a ring. While observing a star's close approach to Neptune, the star's luminosity dipped, but only for several seconds. If rings were in fact present, the star's luminosity would decrease slightly just before the planet's closest approach. The discovery of this moon was purely fortuitous, and occurred as a result of the ongoing search for rings similar to those discovered around Uranus four years earlier. The third moon, later named Larissa, was first observed by Harold J. Kuiper (for whom the Kuiper Belt is named) using photographic plates from the McDonald Observatory in Fort Davis, Texas. The first was Nereid, Neptune's second largest and most massive moon, which was discovered on May 1st, 1949, by Gerard P. It would be almost a century before any other moons would be discovered. It was observed by William Lassell on October 10th, 1846, just seventeen days after Neptune was discovered. Triton, being the largest and most massive of Neptune's moons, was the first to be discovered. Neptune now has 14 recognized satellites, and in honor of of their parent planet, all are named for minor water deities in Greek mythology. ![]() But by the mid-20th century and after, thanks to improvements in ground-based telescopes and the development of robotic space probes, many more moons would be discovered. ![]() Initially, only Triton – Neptune's largest moon – could be observed. ![]()
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