This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Hydra Nix Styx conjunctions cycle. Pluto's moons Hydra blue Nix red and Styx black as controlled by their mutual orbital resonance The view is from the north pole of the system and all motions are counterclockwise The movements shown are actually composite of orbital motion and orbital precession Libration is disregarded Numbers