What is a Blue Moon? It is the 2nd full moon in one (solar) month. That year would have 13 full moons instead of the usual 12. 7 times in 19 years there are 13 instead of 12 and 2015 will have 13. The last time this happened was 2012. The full moons of July were the 2nd and the 31st. The second full moon of the month is called a Blue Moon. Below is a photo from Space.com of that brilliant full moon of July 31.
When someone says “Once in a blue moon” they are saying it is absurd, may not or rarely happens.
The color will not actually be blue unless there has been a volcanic eruption, fires or other gases in the atmosphere. The color would only change during unusual sky conditions. When I was in Minnesota in July I observed the Sun being fire red from the smoke of the forest fires in Canada. I have had several people message me about seeing this past moon being brilliant red and the news last night showed it to be orange. The brilliant colors of the moon are not from a lunar eclipse, but rather effects of smoke in the atmosphere from states away.
There are 20 active fires in the following states. Alaska (1), California (8), Montana (3), New Mexico (2), Oregon (2), Washington (3) and Wyoming (1). Only 3 of these fires are contained.
Click this link for stories of people who have experienced sighting an actual full moon in a blue color: http://www.spaceweather.com/glossary/bluemoonstories.html
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