Astronomy – the systematic study of the stars and other celestial objects – is widely regarded as the world’s oldest science. It began in prehistoric times when early humans first looked up into the sky and wondered: “Why does the Sun rise in the east and set in the west each day?” “Why does the Moon change its shape every night in a monthly cycle?” “Why do the stars dance across the night sky in such regular patterns throughout the year?”
Discovering the basic principles of astronomy helped our remote ancestors to develop an understanding of the calendar, which in turn led to the agricultural revolution after the last Ice Age. This interlinkage of astronomy, calendaring, and agriculture contributed to the invention of writing so that people could record important events that occurred during the passage of time. Some of the earliest examples of writing include records of astronomical events and their significance (for example, planetary motions and lunar festivals).
Astronomy (one of the Seven Liberal Arts) underwent a major revolution with the invention of the telescope in the early 17th century CE and its use by the Italian physicist Galileo Galilei (1564-1642) to study the skies. With the magnifying power of the telescope, Galileo was able to discover sunspots, the phases of Venus, mountains and craters on the Moon, the four major satellites of Jupiter, and stars too dim to be seen with the naked eye. Galileo’s astronomical discoveries turned the medieval worldview upside down and inside out, paving the way for other scientific revolutions in the physical and biological sciences later on.
Along with (and based on) observational studies of celestial objects, astronomy has sought to answer some of the profoundest questions that we have asked ourselves. How did the Universe begin, and how will it end? Does life exist beyond our world? What is humankind’s place in the cosmos? All these ideas – and many more – are studied by professional astronomers, with the enthusiastic support of amateur astronomers who make observations in their backyards with binoculars or small telescopes.
The exploration of outer space over the past six decades has brought astronomy into the mainstream of public awareness. As crewed and automated spacecraft continue to push back the frontiers of human knowledge, answers to age-old questions give birth to completely new questions about the nature of the Universe. To begin your own journey of exploration, be sure to visit the University of Illinois’ Department of Astronomy at http://www.astro.illinois.edu and Parkland College’s Staerkel Planetarium at http://www2.parkland.edu/planetarium.