Archaeoastronomy is the study of ancient (pre‐technological) humankind's awareness of celestial phenomena and its influence on their societies. A number of these influences in ancient societies have been identified, including how structures were built, early forms of calendars, and the development of mathematical concepts.
Ancient structures
Ample evidence exists that in ancient times, many cultural groups all over the world built single structures, buildings, and even cities facing in astronomically significant directions. For example, the Newgrange passage grave in Ireland (circa 3200 B.C.) faces the mid‐winter sunrise, and Stonehenge, in southern England (circa 2800 B.C.), points toward the mid‐summer sunrise. Similarly, various Mayan buildings in Mesoamerica show relationships to significant horizon rise and set positions for the planet Venus.
Early calendars
Before ancient humans recognized that the yearly cycle predictably repeats itself, they regulated agricultural, hunting, and religious activities by directly observing celestial phenomena. These phenomena included solar position against the background of stars, the cyclic north‐south oscillation of the Sun's rise and set positions on the horizon, or the pattern of nighttime constellations. Evidence of early peoples' celestial timekeeping include the orientation of Stonehenge, which suggests a calendrical awareness, and the Sun Circle (circa 1100 A.D.) built by the people of the Indian city of Cahokia, Illinois.
Navigation
When societies embarked on extended travel where natural features on land were not available, the sky provided an alternative means to mark one's position during journeys. The Polynesians were experts at using the apparent positions of stars in the sky to navigate across the vast expanses of the southern Pacific Ocean. In the same manner, traders crossing the featureless tracks of the Sahara Desert used the sky for their directions. It has been argued that our oldest constellations may date from the delineation of stellar patterns as mnemonic devices for Mediterranean navigation as early as 3000 B.C.
Mathematics
In due course, as societies accumulated extensive observations of the sky, there developed the desire to understand celestial events in a quantitative fashion. The 360 degrees of the circle is the most tractable approximation that the Babylonians could make for the annual circuit of the Sun around the sky in 365.25 days. Islamic scholars were inspired to develop spherical trigonometry for navigational reasons as well as for the Islamic tenet to pray toward the city of Mecca.
Other cultural influences
Awareness of phenomena in the sky has affected other aspects of cultures. Descendancy from the celestial deities of the Sun and Moon was used in many past societies to justify political supremacy. The development of mythologies, astrologies, and religions also contain elements that help societies obtain a sense of order regarding the workings of celestial events.