Most likely, the new small satellite of Neptune is an ancient fragment of a much larger moon. The hippocampus covers a diameter of 34 km, and the name was given in honor of the mythological sea horse.
A satellite in 2014 was discovered by astronomer from SETI Mark Shouoltel. For search used photos of the Hubble Space Telescope. He believes that the Hippocampus emerged from debris created billions of years ago, when the comet crashed into the largest internal satellite of Neptune Proteus. The moons rotate at a distance of 12,000 km from each other, but in the past could be located much closer.
This is one of the earliest pictures of the Hippocampus satellite, obtained in 2004 using HST. The object is inside the red frame, and in the upper right is an enlarged version.
Researchers have long suspected that the internal satellites of the planet passed through multiple scenarios of collisions with comets. Detection of the Hippocampus, rotating not far from large Proteus, illustrates this idea even more clearly. However, there is a possibility that the hippocampus is not associated with Proteus at all.
The picture on which the hippocampus was found. The satellite is located inside the red frame, and in the upper right is an enlarged version
In 1989, the Voyager-2 spacecraft found Proteus. This is a dark satellite of irregular shape, which occupies the second place in size (400 km in length) among the lunar family of Neptune.
Voyager 2 sent the first shots of a large crater on the surface. Showalter is sure that thanks to Hubble's photographs, it can be understood that the Hippocampus is only a tiny piece of Proteus.
Two internal satellites with Neptune (right)
Showalter says that he is trying to find more tiny satellites with a Hubble telescope survey. He will not be surprised if a large number is found, but for such searches it is better to have a spacecraft near the planet itself.