Astronomers believe Neptunian moon is lone intact survivor of ancient collision | CNN

Nereid, Neptune’s third-largest moon, could be the only intact survivor from an ancient set of moons destroyed early in the solar system’s history, according to a new analysis based on data from the James Webb Space Telescope. Neptune, the eighth and most distant planet from the sun, stands out among the outer planets in our solar system for its odd group of moons. The other outer giants — Uranus, Saturn and Jupiter — all have a broadly similar, orderly set of satellites, with several larger moons orbiting in the same direction as the host planet’s rotation. But Neptune has a far smaller and more chaotic collection of moons: Triton, Neptune’s largest satellite, dwarfs all the others and orbits in the opposite direction of its host’s rotation. It is the only large moon in the solar system to do so. Astronomers suspect the reason for Triton’s odd behavior is that it didn’t originate from the remnants of Neptune’s formation, which would make it orbit in the same direction as that planet. They hypothesize instead that Triton might have originated from the Kuiper Belt, a ring-shaped region of icy bodies at the edge of the solar system, and entered the Neptunian envir