Once In A Blue Moon

In Lost Horizon, one of my favorite books - and films - the lamasery of Shangri La sits in a valley shadowed by the towering mountain, Karakal, or Blue Moon. Tomorrow night, the world has an opportunity to lift its eyes to another Blue Moon, a name given to a full moon appearing outside the expected monthly cycle. Though the definition may be challenged, everyone agrees that such moons do not come often. Generally, we can expect one about every three years.

Of course, tomorrow's full moon also will be special as it occurs on the last day of the calendar year - at least in most parts of the world. For more information on the elusive meaning of "blue moon," check out this NASA link.

Source: spaceweather.com