Twenty-Eight Spokes on a Ridge

The wheel sits just below the summit of Medicine Mountain on a spur with a long view in three directions. Its plan is simple and its execution is not: a hub cairn roughly twelve feet across, a rim some eighty feet in diameter, and twenty-eight lines of stone joining the two. Six further cairns stand on or near the rim, one of them outside it and joined to the hub by a spoke that runs past the circle. The stone is local limestone, gathered rather than quarried, and the whole structure is laid on the ground surface without excavation. The twenty-eight spokes have drawn more interpretation than anything else on the site, partly because twenty-eight is the number of poles in some Plains ceremonial lodges and the number of days in a lunar month. In 1974 the astronomer John Eddy published measurements arguing that lines between particular cairns mark the summer solstice sunrise and sunset and the heliacal risings of Aldebaran, Rigel and Sirius, with an outlying cairn and the hub forming the solstice sightline.

Later work has been more cautious: the cairns are broad, the sightlines they define are correspondingly wide, and a structure with twenty-eight radiating lines will produce coincidences. What is not in question is that the builders chose a horizon and a height, and that the people who use the site treat its orientation as meaningful.