The full moon that rises on Sunday, Dec. 15 is known as the “rowan moon” in the Celtic tree calendar. Rowan is translated as “little redhead,” and stems from the rowan tree, a red-berried ash native to Europe. Alas, the moon will overshadow the peak of the Geminid meteor shower on Dec. 13, when over 120 meteors an hour will move through the moon-brightened sky on the western horizon. Our shortest day of the year,…