We recently moved to New Mexico and bought a house on a street named Sundagger Loop. I didn’t understand the reference until we caught a documentary on PBS about some building and carvings in a thousand year old site called Chaco Canyon. It seems the carvings and even the alignment of the buildings was used to mark the seasons. A bit like Stonehenge, but way more sophisticated. The Sundagger itself is a dagger-shaped light projected onto a carving that indicates the seasons. There is no actual dagger, just a piece of sunlight. The PBS documentary is available on-line.

The Mystery of Chaco Canyon