After doing my first job during the night shift I headed for Machen Mountain and looking out over The Bristol Channel there was a beautiful glow of the moon on the channel. I set up my tripod to get this long exposure. 8 seconds, blip photo of the moon and it's halo.
A 'blue moon' (however you define it) occurs once every 2.7 years. The first use of the name occured in 1528 (Morris Dictionary) The phrase has nothing to do with the actual color of the moon, although a literal "blue moon" (the moon appearing with a tinge of blue) may occur in certain atmospheric conditions. While most observers perceive the full moon as lasting one night, technically it's an instantaneous event that occurs when the earth, moon, and sun fall in a straight line.
The next blue moon won't occur until 2017! Not rare but doesn't happen often - hence the phrase 'once in a blue moon'.