The Medicine Wheel/Medicine Mountain National Historic Landmark (formerly known as the Bighorn Medicine Wheel) is a medicine wheel

Medicine wheel

Medicine wheels, or sacred hoops, were constructed by laying stones in a particular pattern on the ground. Most medicine wheels follow the basic pattern of having a center of stone, and surrounding that is an outer ring of stones with "spokes", or lines of rocks radiating from the center...

 located in the Big Horn Mountains

Big Horn Mountains

The Big Horn Mountains are a mountain range in northern Wyoming and southern Montana in the United States, forming a northwest-trending spur from the Rocky Mountains extending approximately 200 miles northward on the Great Plains...

 of the U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of Wyoming

Wyoming

Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...

.

For centuries, the Bighorn Medicine Wheel has been used by Crow youth for fasting and vision quests. Native Americans also go to Bighorn to offer thanks for the creation that sustains them, placing a buffalo skull on the center cairn as a prayer offering. Prayers are offering here for healing, and atonement is made for harm done to others and to Mother Earth.

The structure is located at an altitude of nearly 10000 feet (3,048 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, 25 yards (22.9 m) in diameter, 28 spokes extending from the rim to the center, and a series of seven cairn

Cairn

Cairn is a term used mainly in the English-speaking world for a man-made pile of stones. It comes from the or . Cairns are found all over the world in uplands, on moorland, on mountaintops, near waterways and on sea cliffs, and also in barren desert and tundra areas...

s. Cairn O is at the center of the structure and is almost 10 feet (3 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

Summer solstice

The summer solstice occurs exactly when the axial tilt of a planet's semi-axis in a given hemisphere is most inclined towards the star that it orbits. Earth's maximum axial tilt to our star, the Sun, during a solstice is 23° 26'. Though the summer solstice is an instant in time, the term is also...

 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

Sirius

Sirius is the brightest star in the night sky. With a visual apparent magnitude of −1.46, it is almost twice as bright as Canopus, the next brightest star. The name "Sirius" is derived from the Ancient Greek: Seirios . The star has the Bayer designation Alpha Canis Majoris...

, Aldebaran

Aldebaran

Aldebaran is a red giant star located about 65 light years away in the zodiac constellation of Taurus. With an average apparent magnitude of 0.87 it is the brightest star in the constellation and is one of the brightest stars in the nighttime sky...

, and Rigel

Rigel

Rigel is the brightest star in the constellation Orion and the sixth brightest star in the sky, with visual magnitude 0.18...

, respectively. Observing the first yearly heliacal rising

Heliacal rising

The heliacal rising of a star occurs when it first becomes visible above the eastern horizon for a brief moment just before sunrise, after a period of time when it had not been visible....

 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 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 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.

The site was declared a National Historic Landmark

National Historic Landmark

A National Historic Landmark is a building, site, structure, object, or district, that is officially recognized by the United States government for its historical significance...

in 1970, and renamed as the Medicine Wheel/Medicine Mountain National Historic Landmark in 2011.

External links

• Medicine Wheel National Historic Landmark at the Wyoming State Historic Preservation Office
• A Report on the Medicine Wheel
• Medicine Wheel/Medicine Mountain NHL District