As a child I'd heard this expression many times and always wanted to see a blue moon. Blue being my favorite color and the full moon a beautiful celestial event, I could not imagine a prettier site. So the first time a blue moon happened when I was old enough to know, I waited outside expectantly for the moon to rise. Imagine my confusion when the moon was still a luminous pearly white!
We will be experiencing a "blue moon" this Friday, August 31, 2012. I will have to go check again, just to make sure it is not a cornflower blue. Maybe just in my imagination.