Blue Moon

A blue moon is a moon that looks blue in color as a result of atmospheric effects or the second occurrence of a full moon occurring in the same month in a given calendar. It is not really blue in color but the term is used to refer to either a calendrical or seasonal event. 

Calendrical Blue Moon:

This is the more popular meaning and it is the second full moon in one calendar month. 

Due to the fact that the lunar cycle is roughly 29.5 days, there is a possibility of a full moon appearing at the start of a month, leaving enough time during a month to get another full moon that will appear at the end of the month. 

The occurrence of this kind of blue moon occurs about every two to three years. 

Seasonal Blue Moon:

This is the third full moon showing up in a season (spring, summer, fall, or winter) in which there are four full moons having four full moons in one season. 

In general, a season enjoys three full moons and the fourth one is viewed as the extra/ blue moon. 

Not Actually Blue:

In spite of the name, a blue moon does not often have a blue color. 

Blue moon Blue moon is sometimes constructed metaphorically to denote a rare or out of the ordinary event; the astronomical use denotes the frequency of full moons. 

Blue Moons Atmospheric:

There are uncommon situations whereby a moon may appear to have a blue color because of atmospheric phenomenon such as volcanic eruptions or massive forest fires that can bend red light and blue light can pass through. 

To put it briefly, a blue moon is an amusing astronomical phenomena either due to being the second full moon in a month or it is the third in a series of four full moons in a season but it does not always have to be a blue moon in the color sense. 

What is a blue moon? – Seeking clarity on the definition (second full moon in a calendar month or third of four in a season) and its true meaning. 

Prevention, Library of Congress

When is the next blue moon? – Users frequently wonder about upcoming Blue Moon dates and cycles. 

New York Post, Prevention

Blue moon meaning – Queries often explore cultural, colloquial, and astronomical definitions. 

Prevention, Spiritual Ark

Blue moon origin – Searches dive into the phrase's origins (16th-century usage, Farmer’s Almanac, etc.). 

Wikipedia, Prevention

Blue moon appearance blue? – Clarifications around whether a Blue Moon appears blue or truly is that color.