Archaeoastronomy is the study of the history of human interaction with the cosmos. It is a broad, and relatively new science that takes on attributes of archaeology, anthropology, astronomy, statistics, and history. Archaeoastronomers try to figure out how ancient civilizations interacted with the heavens, how they interpreted the movements of celestial bodies, and what significance this knowledge played in their culture. The bulk of archaeoastronomy focuses on architectural structures, but scientists also look at pictorial data, folklore, artifacts, ancient calendars, and when they exist, written records.
The roots of archaeoastronomy began in the late 18th and early 19th centuries when archaeologists began studying structures in the Middle East and Europe with significant astronomical orientation. Several astronomers and researchers have been named as founders, but it was really a handful of curious scientists who first began to develop archaeoastronomy into a discipline of it own. In 1740, William Stuckeley began studying the placement of the monoliths of Stonehenge. It was two 19th century astronomers - Richard Proctor and Charles Piazzi Smyth - who first noticed and investigated the orientation of the pyramids in relation to the movement of celestial bodies. Alexander Thom did extensive work, taking readings of the alignment of the sun with monoliths in Britain. One of the predominate archaeoastronomists today is Clive Ruggles, a professor at the University of Leicester. He has had many articles and books published on his findings and theories, including the Encyclopedia of Cosmologies and Myth, which is an overall study of the field. He also has compiled a library of photographs of cosmological significant structures from all over the world.
A few examples of archaeoastronomical study include the Pyramid of Kukulkan in the Yucatan, Machu Pichu in Peru, and Newgrange in Ireland. The Pyramid of Kukulkan, also known as El Castillo, is a magnificent 4-sided, 30-meter high structure built by the ancient Maya to honor the feathered serpent god, Kukulkan. On each side is a staircase, with 91 steps. There are 365 steps in total, including the step to the upper platform at the top of the pyramid. During both equinoxes, the light just before sunset will cast the shadow of a snake traveling down the steps of the pyramid. Machu Pichu, The Lost City of the Incas, is a series of ruins, that were built probably as a religious retreat around 1460 AD. In one of the buildings, called Torreon, the sun radiates through the northeastern window on the summer solstice, illuminating a central alter. Newgrange, which wasn't discovered until 1966, dates back to 3100 BC. It is a 19 meter passage which ends in a vaulted inner chamber. During the winter solstice the chamber is lit for 17 minutes when the sun shines through a small roofbox over the entrance.
Because of the highly speculative nature of this discipline, it is not recognized everywhere in the world. Clive Ruggles is quoted as saying, it is " a field with academic work of high quality at one end, but uncontrolled speculation bordering on lunacy at the other." There is just not enough hard evidence to verify a lot of the work of archaeoastronomers. Even when their theories are proved, no one can say why ancient cultures have gone to such lengths to build structures based on the cosmos. Was it religion? Was it a need to honor, and perhaps fear the sun, the moon, and the stars? Or was it just that the cosmos were once an integral part of human life, as ancient peoples watched their myths play out in the night sky?