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Neptune XIV

There are seven known small moons within the orbit of Neptune's massive major moon Triton, and Hippocamp is one of these. These inner moons are all relatively small bodies (the largest, Proteus, is about four hundred kilometres in diameter) but even among these small moons, Hippocamp is tiny, with an estimated mean diameter of just 35 km.

The inner moons of Neptune were heavily disrupted in the distant past, when their parent planet captured an immense object that would become the moon Triton. The planet's existing moon system broke apart at this time and reformed, giving rise to the group of inner moons that includes Proteus and Hippocamp. In fact Proteus and Hippocamp follow similar orbits (of the two, Hippocamp orbits slightly closer to Neptune) implying a relationship in the past. It has been suggested that Hippocamp was in fact part of Proteus at one time, but was ejected by an impact on Proteus' surface (the remnant of which can be seen in a huge crater named Pharos).

By convention, moons in the Neptunian system are named for mythological beings associated with the god Neptune (or his Greek equivalent Poseidon). The moon Hippocamp takes its name from the monstrous 'sea-horses' that were said to accompany the god and carry his chariot across the waves.


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