Using images taken by spaceWith the Hubble telescope, a group of astronomers from the SETI institute searching for alien civilizations discovered a tiny new satellite from Neptune. The open moon, called the Hippocampus, in honor of the sea monster from Greek mythology, increases the total number of satellites of the gas giant to 14, according to an article published in the journal Nature.
The size of an open satellite is only about34 kilometers in diameter, which makes it the “youngest” among the moons of Neptune. The object is one of seven (the other six: Proteus, Larissa, Despina, Galatea, Thalassa and Naiad) of the internal satellites of the planet, which are very closely wrapped around the gas giant (it takes about 24 hours for one revolution around the planet).
Dimensions of the Hippocampus relative to other Neptune moons
When in 1989, the spacecraft "Voyager-2"flew past Neptune, he immediately found six new internal satellites of the planet. Seven other satellites rotate at a greater distance. The open Hippocampus, in turn, is the second most remote satellite of the inner group of moons. The poor viewing angle during shooting and the fact that the satellite itself is rather dark helped him to escape from the gaze of "Voyager-2".
To study in detail the satellites of the gas giantMark Showalter, a senior researcher at the SETI Institute, and his colleagues monitored the system using the Hubble Space Telescope. Scientists put pictures together to increase the effective exposure time, and as a result discovered another moon, which Voyager 2 did not notice in 1989.
Astronomers suggest that the Hippocampusis an ancient fragment of Proteus, the largest satellite of the inner group, which is about 4000 times larger than the Hippocampus. The orbit of the latter lies near the Proteus orbit, approximately 12,000 kilometers. On the surface of the Proteus itself, there is an unexpectedly large crater of Pharos, about 240 kilometers in size, which indicates that another celestial body collided with a satellite in the past. Hence the hypothesis that the Hippocampus is part of Proteus.
The very first Hippocampus image taken by the Hubble telescope in 2004
"The discovery of a tiny hippocampus allowsexpand the boundaries of our understanding of the device of the internal system of satellites of Neptune. Proteus and the Hippocampus in the past were located even closer to each other, but due to gravitational interactions with Neptune, with time it moved away from it. Now we can study in more detail the connection between these moons, ”the scientists note in their study.
Given the speed with which Proteus could migrate further from Neptune, a team of researchers suggests that the age of the Hippocampus may be several billion years.
The study also makes another hypothesis. Due to the fact that Triton is moving in a retrograde orbit (against the direction of the movement of Neptune himself) and has a composition similar to Pluto, scientists assume that he once belonged to the Kuiper belt, and then was captured by Neptune's gravity. Discovered by Voyager-2, the moons most likely formed after this event. It is possible that when Neptune captured Triton, the planet had a completely different set of internal satellites, but Triton's gravity led to their collision, which in turn led to the appearance of very thin rings around Neptune and the current set of internal moons.
Such random events, scientists believe,“They help to demonstrate the important role of collisions of celestial bodies and changes of their orbits, which in this case led to the formation of the Neptune system that we are seeing now.
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