Blue Moon

The most literal meaning of blue moon is when the moon (not necessarily a full moon) appears to a casual observer to be unusually bluish, which is a rare event.

Owing to sulphur particles in the upper atmosphere from a forest fire covering 250,000 acres between Mile 103 and Mile119 on the Alaska Highway in northern British Columbia, Canada blue moon occured. The moon took on a bluish color, as seer from Great Britain, on the night of Sept 26, 1950. The moon appeared green after the Krakotoa eruption oF Aug 27,1883 and in Stockholm for 3 min on Jan 17, 1884.