Medicine Wheel National Historic Landmark

Infobox_nrhp | name =Medicine Wheel
nrhp_type = nhl


caption = The Medicine Wheel in Big Horn County, Wyoming, USA
nearest_city= Kane, Wyoming
locmapin = Wyoming
area =
architect=
architecture=
designated= August 29, 1970cite web|url=http://tps.cr.nps.gov/nhl/detail.cfm?ResourceId=841&ResourceType=Site
title=Medecine Wheel |accessdate=2008-06-27|work=National Historic Landmark summary listing|publisher=National Park Service]
added = April 16, 1969cite web|url=http://www.nr.nps.gov/|title=National Register Information System|date=2008-04-15|work=National Register of Historic Places|publisher=National Park Service]
governing_body = FOREST SERVICE
refnum=69000184

The Bighorn Medicine Wheel is a medicine wheel located in the Big Horn Mountains of the U.S. state of Wyoming.

The structure is located at an altitude of nearly convert|10000|ft|m, near the summit of Medicine Mountain. It is a precolumbian structure, built from roughly loaf-sized stones gathered from the surrounding area. The structure consists of a circular rim, convert|25|yd|m in diameter, 28 spokes extending from the rim to the center, and a series of seven cairns. Cairn O is at the center of the structure and is almost convert|10|ft|m in diameter. Cairns A - F are at or near the rim, and are considerably smaller. Astronomer John Eddy investigated this 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 at predicting how many days remained before the summer solstice, as the first heliacal rise of a star occurs on the same date. 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 A.D. 1200 and A.D. 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 A.D. 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 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 A.D. 1050 and A.D. 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.

It was declared a National Historic Landmark in 1970.citation|title=PDFlink| [http://pdfhost.focus.nps.gov/docs/NHLS/Text/69000184.pdf National Register of Historic Places Inventory-Nomination: Medicine Wheel] |32 KB|date=__, 19__ |author=___WEBSITE DOWN ADD LATER___ |publisher=National Park Service and PDFlink| [http://pdfhost.focus.nps.gov/docs/NHLS/Photos/69000184.pdf "Accompanying __ photos, exterior and interior, from 19__"] |32 KB]

References

External links