@redsad
Irrelevant facts:
Newton was also an Alchemist & thought 7 was of special significance (Music of the Spheres?), so arbitrarily names or picked 7 colours for the rainbow or light split by a prism. There are thousands of colours visible. The "Gay" flag has 6 colours.

There is no dark side to the moon. It's tidily locked so as it orbits the Earth, it rotates to keep the same face. We see slightly more than 50%. The far side gets plenty of sunshine & photographed in 1950s by Russia.

@raymaccarthy @redsad Didn't Newton invent an extra colour (indigo) just to make the number up to seven?

Also, though there isn't a permanent Dark Side, there is a distinct Far Side (if we ignore wobbles). But as a title, "Far Side of the Moon" doesn't really convey the dark tone of the album.