Note 18 — Chapter XIII · THE MOON AS A WORLD: DAY AND NIGHT UPON ITS SURFACE.

We see this reddening during an eclipse of the moon (when the event we are describing—an eclipse of the sun visible from the moon—really takes place). The blood-red colour has often struck observers very forcibly, and it has indeed been suggested that the appearance may be the innocent and oft-repeated fulfilment of the prophetic allusion to the moon being “turned into blood.”