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:
Orbital resonance of Mercury. en Selfmade animation of Mercury's orbital resonance based on File Mercury's orbital resonance Made in Flash MX After one orbit Mercury has rotated times so after two complete orbits the same hemisphere is again illuminated own User Age at org en Public domain released by author en Age original