Beneath a bluff braced against blazing blue sky, the ancient ruins of a Chacoan community unfold below two rock pillars in southern Colorado. Like the better-known ruins at nearby Chaco Canyon and Mesa Verde, these sturdy pit houses and kivas made of pale stones are stunning in their tight masonry and sheer range—an estimated 6 million stones moved by hand, serving a population that was likely larger than what exists in the area today.
Pretty magical, to be sure. But there’s something even more mysterious and special going on here. It’s a relatively recent discovery, and one that took many trained eyes to see, perhaps because it’s a rare celestial event seen only every 18 years.
When I first started reading about a Major Lunar Standstill, I was a bit skeptical—how had I not heard of such a thing, sky lover that I am? Certainly, we all know the sun has a standstill: Solstice, with sol meaning “sun” and stit meaning “stopped,” is the day when the sun “pauses” in the sky at its highest northern point and begins to move south again. Most of us are aware, too, that cultures around the world have marked the solstice and equinoxes—from Stonehenge to Machu Picchu to Chaco Canyon, important structures align with the sun’s movement across the sky.
The moon, too, has a, which I find an endearingly beautiful word. And while most of us are familiar with the rotation from full to gibbous to new moon, my guess is most don’t know about a slower cycle as it moves from north to south, which is caused by a slight wobble in its orbit around the Earth. This cycle takes 18.6 years to complete, and when it reaches its apogee, it appears to rise in the same area for about three years, known as the Major Lunar Standstill. This is such a long and subtle cycle of moving across the horizon, it’s no wonder that most of us don’t notice, nor are aware that we’re currently experiencing a lunar standstill, which will occur only a few times during the course of our lives.
