Does this somewhat eerie image, from Astronomy Picture of the Day for 19/8/23, depict Saturn and one of its moons? Or is it even from another solar system?

No. It is in fact the planet Neptune captured by the James Webb Telescope in infra-red light. Its largest moon, Triton, brighter than its primary in reflected sunlight, is at the top left showing the James Webb Telescope’s typical diffraction spikes.

This is via Astronomy Picture of the Day, 26//8/14.

Neptune’s largest moon Triton.

The movie has been stitched together from still pictures taken by Voyager 2 on its fly past.

The Voyager missions must have been Nasa’s most successful unmanned investigations of the Solar System.

Apparently the green colour of the moon is real.