The meaning of Christmas lives in its folklore, and it’s amazing how many of the Christmases we remember were so enchanted by one facet of Holiday allure that often goes unsung: the glorious full moon around Christmas time.
The December full moon is called the Cold Moon. And while this year’s Cold Moon won’t fall exactly on Christmas, it will come quite close, arriving on Dec. 26. It may be seen shining remarkably high in the sky by many North Americans on Boxing Day eve—perhaps illuminating their drive home from the shopping mall on one of the shortest days of the year.
Here’s what you need to know about the full Cold Moon, including some folklore derived from ancestral European and Native American cultures, plus some astronomical tidbits.
This year’s December full moon will fall the day after Christmas, on Dec. 26, at 7:33 p.m. EST, three hours after sunset on the eastern seaboard. Naturally, that will be on Dec. 27 for nearly the entire Eastern Hemisphere.
Although the moon will reach full illumination on Boxing Day, it will also appear plenty full on the days immediately preceding and following this—that’s because full moons technically occur when directly opposite the sun as viewed from Earth, so it won’t have moved that far by then.
The Cold Moon will appear almost, but not quite, perfectly round on both the nights of Dec. 25 and 27. So, presumably, Santa Claus will have bountiful moonlight by which to deliver presents on Christmas Eve; while there will be full illumination in store for shoppers returning home, bags in hand, from Boxing Day sales also.
Speaking of full moons falling exactly on Christmas (which this year’s won’t) that only happens once every 19 years. The last time was in 2015 while the next full Cold Moon on Christmas will be in 2034.
Actually, this business of Holiday Season moons harks back to a timeless Christmas classic—one that most Americans are familiar with—and probably traces back even earlier. In the children’s poem “The Night Before Christmas” (whose original title was “A Visit from Saint Nicolas”), published in 1823, the narrator “tore open the shutters and threw up the sash” to catch a glimpse of Santa Claus, whom he heard outside.
Gazing out, he proclaimed: “The moon on the breast of the new-fallen snow gave the luster of mid-day to objects below.”
There are other full moon names derived from Native tribes, including Frost Exploding Trees Moon (Cree), Hoar Frost Moon (Cree), Snow Moon (Haida and Cherokee), and Winter Maker Moon (Western Abenaki). The Mohicans called it the Long Night Moon, as it rises around the longest night of the year—the winter solstice.
Now, to understand the winter solstice and how it lifts the moon so high up, we must first learn what causes the seasons. The tilt of the Earth’s axis is responsible for the seasons, creating variations in sunlight exposure as the Earth orbits. It also makes the sun’s arc drop in the sky in December, in the thick of winter. And, when said arc finally reaches the floor we have our shortest day—the winter solstice. The sun officially bottoms out at the lowest point.
Lastly, we need to consider the moon’s sky path. It aligns almost exactly with the sun’s; both their orbital planes are nearly identical. So try to imagine now what would happen if the full moon—which, remember, is always directly opposite the sun—occurred during the winter solstice: when the sun bottoms out, the full moon on the far side hits the roof.
This year’s winter solstice is on Dec. 21, so we can expect a very high-rising full Cold Moon on the night of Dec. 26, making your Boxing Day drive home a well-lit one. But there will probably be abundant moonlight on Christmas Eve, too—presumably guiding Saint Nick and his reindeer as they spread festive cheer all along their way.
