Description : The Medicine Wheel/Medicine Mountain National Historic Landmark (formerly known as the Bighorn Medicine Wheel) is a medicine wheel located in the Bighorn National Forest, in the U.S. state of Wyoming. The Medicine Wheel at Medicine Mountain is a large stone structure made of local white limestone laid upon a bedrock of limestone. It is both a place of sacred ceremony and scientific inquiry. In Native Science these uses are not distinguished as separate as they are in Western science. The cultural history of the Big Horn Mountains, home to the Big Horn Medicine Wheel, dates back over ten thousand years. The Big Horn Medicine Wheel is one of four or five astronomically complex wheels that are publicly known to exist in the Rocky Mountain region. It is of a type termed Subgroup 6, "A prominent central stone cairn surrounded by a stone ring. Two or more interior stone lines connect the stone ring to the cairn." by John Brumley. Another of this Subgroup type is the Majorville Wheel in Alberta, Canada. The Majorville Wheel with a similar complex design matching the Big Horn Medicine Wheel has been dated archaeologically to 3200 BC. Smaller, less complex wheels may have astronomical significance, such as solstice alignments and east-west orientations. The larger complex wheels are capable of tracking several different cosmic cycles, including the precession of the equinoxes, the Moon's phases, lunar and solar eclipse cycles, and planets' orbital cycles. These astronomical wheels mirror the north ecliptic polar region of the sky and are useful as celestial grids to track changes over millennial time periods. Astronomer John Eddy investigated the Big Horn Medicine Wheel's structure in 1972 and made a number of important discoveries, publishing his findings in Astronomical Alignment of the Big Horn Medicine Wheel, Science 184 (1974): 1031-43. He found that cairns E and O were aligned in the direction of summer solstice sunrise, using cairn E for a backsight and cairn O as a foresight, and that cairns C and O were aligned in the direction of summer solstice sunset, using C as a backsight and O as a foresight. Further, he found that cairn pairs FO, FA, and FB correspond to the rising points of the stars Sirius, Aldebaran, and Rigel, respectively. Observing the first yearly heliacal rising of these stars would have been an effective tool for determining the progress of the solar year, as the first heliacal rise of a star occurs on the same date (relative to the solstices) each year. Rising positions of stars change very slowly over the centuries, due to the Earth's precession, so the directions of these cairn pairs can be used to project at what date they aligned best with the rising points of these stars. The FA Aldebaran alignment would have worked best between AD 1200 and AD 1700. Further, precession changes the date of first helical rise: Although today the first heliacal rise of Aldebaran is a few days after the summer solstice, between AD 1200 and 1700, the first heliacal rise of Aldebaran would have been just before the summer solstice, allowing an observer to predict the coming of this event. Astronomer Jack Robinson from the University of South Florida has further proposed that cairn pair FD was used to observe the rising of the star Fomalhaut, which would have lined up with its rising point between AD 1050 and AD 1450, when Fomalhaut had its first heliacal rise roughly a month before the summer solstice. A carbon date for the Bighorn Medicine Wheel comes from a piece of wood found in cairn F, corresponding to an age of no more than 220 years, roughly in the middle of the 18th century. However, this date can only be considered as a minimum age, as the wood may have become lodged in the cairn after construction. Stated by Don Grey in his, "Summary Report," page 317 of the 1958 Wyoming Archaeology Society's excavation of the Wheel, "In the large cairn on the northwest side of the structure was found a piece of wood pinned down between the courses of stone in the wall. A sample was taken…for dating."
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