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Space Topics: Planetary AnalogsStars Above, Earth BelowAstronomy and Space Exploration in America's National Parks
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Winter Solstice Sunrise
A small door high in a wall of the Great House Pueblo Bonito allows the first rays of sunlight to enter the room during winter. On those days immediately around the winter solstice the square light of the door is perfectly centered in the far corner of the room. As the sun rises the spot of light slowly moves out of the corner. Credit: Tyler Nordgren |
The Center of the Universe
Redlands, CA -- I have been back from Chaco Culture National Historical Park for two weeks and still think about it daily. It was an amazing place that deeply affected me. Part of it was the maddening weather which led to an intense feeling of isolation as I only dared make the all-day trip to town once during my time there. Because the park is so isolated, everyone there, both visitors and park service employees, has made the effort to be there specifically and all share a passion for the place (as a visitor it also doesn’t hurt that on some days you may be the only one and thus have everyone’s complete and undivided attention).
This was demonstrated perfectly on my last day, the winter solstice, when a dozen hardy folks made the trek out to Pueblo Bonito before dawn to witness the rising sun’s light shining perfectly through a high door into the far corner of a hard to reach room. We all shared something special and personal as we were lead by Park Interpreter GB Cornucopia, very nearly the living personification of the park, along an icy path to witness this event for ourselves. Every one of us froze up there, but did it willingly as we watched this alignment of sun, door and stone that marks the sun’s southern-most position on the horizon. And that is the final reason that Chaco means so much to me. As I wrote last time, nearly every rock, building, and petroglyph in the park speaks of a deep interest in observing how our universe works. Even if some of that interest is only on our end of the thousand-year timeline in which people have been in the park, the fact that everyone around that room was there on that day, meant that we all learned a little bit more about our Earth as a planet and its relationship to our star, the Sun.
Today, we live in such a wonderfully technological society that we largely do not need to pay attention to the seasons or even the time of day. The amount of light and heat in our homes is mostly divorced from the tilt or orientation of our planet relative to the sun. The foods we find in the store are nearly independent of those seasons which are astronomical in origin. The very origin of a “day”, “month”, or “year” are lost as we forget they have any connection to our planet, sun, or moon. As a result, astronomy is now something that is seen as completely independent of, and incidental to, our lives.
Perhaps it is for all of these reasons that the general public is so fascinated by ancient astronomical alignments. “How could these people have possibly known these things?” we ask, when most of us barely know them ourselves (and they didn’t even have GPS units or the Internet)? This is a question that frustrates some archaeoastronomers. It is especially frustrating when some people begin to mythologize people like the Chacoans as some sort of ancient Einsteins. By labeling them fantastic astronomical geniuses, or devising complex and elaborate astronomical alignments where none existed or were intended, we do a disservice to their (and our) shared human nature. Because that human nature is to observe and understand, and it is something any of us can do, a thousand years ago in a canyon in New Mexico, or today in our homes and backyards. We just need to walk outside and be curious.
Star Trails and Light Pollution over Pueblo Bonito
The great ceremonial kiva in Pueblo Bonito is aligned almost perfectly with the rotation axis of the Earth. This can be seen by noticing the North Star at the center of the concentric circle of stars almost directly behind the northern stairway into the kiva. The 26,000 year precession of the Earth means that a thousand years ago when this chamber was built, the North Star would have been located five degrees away from its current position over the Earth's North Pole. Credit: Tyler Nordgren |
Sunrise from Penasco Blanco
Ranger GB Cornucopia (center), Kansas State English professor Dr. Elizabeth Dodd (left) and I (right) made the three-mile hike to Penasco Blanco under darkness in order to test a potential winter solstice sunrise alignment. Five days before the solstice the sun rises to the left of the "nose" on the horizon as viewed from a central kiva. The ruins of Pueblo Bonito are visible in the sunbeam before us. Credit: Tyler Nordgren |
Here at the start of the new year I want to thank everyone who has helped me along the way over the last six months. The numbers are far too numerous to name individually, but if you are reading this you know who you are.
Right now I am at home carefully watching the weather. This will be the second straight drive to a park which has coincided with a major Pacific storm. During the three weeks I will be at the Grand Canyon, I will be spending four nights (January 14-17) down at the bottom at Phantom Ranch. During one of those nights, depending on the weather, I’ll be giving an evening astronomy talk to the public. If you are up for the hike and get a place to stay down there, keep your eyes posted for news.
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