Archaeoastronomy

Archaeoastronomy, study of the astronomical achievements made by ancient peoples, extending from prehistoric times to the advanced cultures that developed in the Middle East and in the Americas. Archaeoastronomy involves the combined efforts of astronomers, archaeologists, ethnographers, and other scientists who interpret the meaning of architectural remains and written records of astronomical significance. Such remains and records can include rock paintings; the medicine wheels of native North Americans; much larger megalithic structures such as Britain’s Stonehenge; and the sophisticated calendars developed by the ancient Egyptians, the Babylonians, the Aztecs, and the Maya. Modern scientific astronomy is considered to have begun with the ancient Greeks (see History of Astronomy).

The remnants of cultures throughout the world show that many ancient peoples were concerned with the complex regularity of the motions of the Sun, Moon, planets, and stars, and with unusual occurrences such as eclipses and the appearance of a nova or a comet in the night sky. The sky was a dominating feature of the human world in ancient times and ancient peoples organized patterns of stars into constellations. The regularity of celestial events provided ancient peoples with a means of understanding and of bringing order to their world. It enabled ancient peoples to measure the passage of time, to predict the recurrence of seasonal events that were essential for agriculture, to travel and navigate for long distances on land or sea, and to develop the calendars needed for their complex societies. In addition, the motions of planets and unusual celestial events were often thought to influence human existence, leading to beliefs in astrology and in omens that could predict disasters, deaths of leaders, or the outcomes of battles.

Archaeoastronomy as a scientific discipline began in the late 18th and early 19th centuries with the first studies of how the pyramids of Egypt and various ancient temples and structures in the Middle East and Europe were apparently oriented to objects and events in the sky. These scholarly efforts intensified greatly in the late 19th century with the work of the English astronomer Sir Joseph Norman Lockyer and others. Studies of Stonehenge and similar early megaliths have clearly indicated that these structures were oriented on celestial events such as the summer solstice. Temples and other constructions were also used to mark the phases of the Moon and the rising of certain bright stars such as Sirius. In the Americas the large, circular patterns of stone called medicine wheels, as well as the structures left by the Mound Builders, were similarly oriented on the summer solstice; and rock paintings appear to record such events as the ad 1054 supernova that created the Crab Nebula.

The ways that ancient peoples made astronomical observations could vary according to their location on Earth’s surface. For example, in tropical regions such as the Pacific Islands, people recorded the directions for long sea journeys using a system of coordinates based on the horizon, rather than on the ecliptic (path of the Sun across the sky) as used by peoples in higher latitudes. Researchers are beginning to appreciate the sophistication of some of these ancient systems of using stars and other objects in the sky to navigate and tell time.