Blue Moon Eclipse, Horseshoe Bend, Page Arizona. Once in a blue moon is a metaphor for rare events. Blue moons aren't really blue, they are merely a second blue moon of a calendar month. As we know moon eclipses are even rarer than blue moons, here we have an eclipsing blue moon.
Rare enough I drove 500 miles to capture this on as the weather at my home would not provide a window to the moon.