Astronomy

The modern science of astronomy has its roots in the earliest civilizations of Mesopotamia, Egypt, Greece, China, India, and Mesoamerica, where it interacted with religious traditions. Ancient astronomy was concerned primarily with the positions and motions of visible celestial bodies, whereas modern astronomy studies all bodies and matter in the universe, including also their compositions, histories, and destinies. In ancient societies, astronomical calculations were fundamental to the development of both calendars and astrology—the science and art of finding in the movements of heavenly bodies either predictions of, or causes for, human behavior and natural events on earth. However, the distinction of astronomy as a science and astrology as a divinatory practice is a modern one, as it is predicated on modern ideas of what constitutes scientific thought. In Christianity and Judaism, advances in modern astronomy, alongside those in geology and biology, have created new hermeneutical stresses on the interpretation of the creation stories and motifs found in the Hebrew and Christian Bibles. These stresses have been most keenly felt in post-Reformation Protestantism, with its focus on the Bible as the sole authority for salvation.

Astronomers in the medieval Islamic world improved on the Greek astronomer Ptolemy's geocentric model of the universe by incorporating additional learning from Persia, India, and China. Muslim astronomers developed a robust tradition of observational astronomy aided by applied trigonometry and detailed astronomical tables. This tradition was transmitted to Europe during the Middle Ages.

The age of modern astronomy begins in the 16th century with Nicolaus Copernicus, who, drawing on the work of Ibn al-Shat.ir, proposed a heliocentric solar system. In the 17th century, Galileo Galilei demonstrated the utility of the telescope in astronomical observation and in so doing provided significant evidence for Copernicus's theory, and Johannes Kepler refined the Copernican system by developing the laws of planetary motion. Kepler's laws were soon corroborated and generalized by Isaac Newton's laws of motion and universal gravitation. In the early 20th century, Edwin Hubble provided convincing empirical evidence that the universe is expanding; by the 1960s, the age of the universe was calculated to be approximately 14 billion years, having emerged suddenly from an extremely hot and dense singularity in an event known as the Big Bang.

Ethnoastronomy is the study of how celestial phenomena are perceived, understood, and used by contemporary peoples not subscribing to modern astronomical paradigms. This field combines knowledge of modern astronomy with ethnographic fieldwork. Archaeoastronomy is the study of past peoples’ astronomies, and as such, it combines astronomical knowledge with archaeological and historical methods. Both disciplines emerged in the 1970s and have tended to concentrate on the astronomies of the indigenous peoples of the Americas, for whom astronomical beliefs play an important role in their rich and diverse mythologies and ritual practices.