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Neptune VII

One of a group of small inner moons of the planet Neptune. Orbiting at a distance of some 73,500 km from the planet, Larissa is the outermost of this group of small moons (the others, counting inward toward Neptune, are Galatea, Despina, Thalassa and Naiad). When Neptune captured its massive outer moon Triton, its existing moon system was broken apart. Larissa and its fellow inner moons are thought to consist of 'rubble piles', masses of material from Neptune's original shattered moons that later coalesced to form new moons.

All of these close moons complete their orbits of Neptune rapidly. Larissa orbits the planet in a little over twelve hours, and rotates on its axis in the same period, so it always shows the same face to Neptune. The largest of the five inner moons, it has an average diameter of a little under 200 kilometres (it is irregular in shape, with its longest axis measuring 216 km, while its shortest is 168 km). The surface is dark and irregular, and covered in cratering.

Following convention for the moons of Neptune, Larissa takes its name from a mythological character connected with the classical gods of the sea. In this case, the mythological Larissa was a sea-nymph, the daughter of Pelasgus, who became a consort of the sea-god Poseidon.


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