Do you know that the term “Blue Moon” speaks of emotions rather than hue. When a month is blessed with two full moons the latter is referred to as Blue. 
I found this article to explain a few. Via: The Farmers Almanac.
Many legends are associated with the Blue Moon, including how it may reflect sadness. In Eskimo folklore, for example, the “Blue Moon” is believed to result from the sadness of the Moon needing to keep his distance from his lover, the Sun, for fear of overshadowing her with reflected glory. Needing to be apart made this mythical Moon sad, and hence, blue.
In Medieval Europe, the Blue Moon was associated with devastation and disease, whether from plagues, natural disasters, famine, or other factors. This further connected the idea of sadness around this Moon. Because blue is a color associated with water, including tears and rain, it also bears this connection.
Yet not all blue references are sad. The color is also associated with protection, particularly from evil spirits, a strong belief in many Eastern European, Middle Eastern, and Asian cultures. Amulets are often blue to harness the protective nature of the color blue.
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