A Blue moon is either astronomical event or used in a phrase as a colloquialism.
Astronomical Event Edit
A Blue Moon occurs when a month has two full moons in it or four full moons within three months.
Traditionally, the colloquialism Blue Moon means an unusual and not very frequent occurence.
In the World of Nausicaä Edit
A Blue Moon seems to be a colloquialism, based upon the sentence structure used .
- ↑ DE1a pg 64
a See Page Conversions Between Editions to convert Deluxe Edition volume 1 (DE1) to other editions