Remember Eclipse by Pink Floyd, which concludes Dark Side of the Moon?

The album famously finishes with a mumbled extract from some words of the recording studio doorman, Gerry O’Driscoll:

There is no dark side in the moon, really. Matter of fact it’s all dark. The only thing that makes it look light is the sun

It turns out that Mr O’Driscoll was not quite right. It’s all only 73% dark?