THE NATURE OF ASTRONOMY

Astronomy is the science of the universe. It deals with individual objects such as planets, moons, stars, and galaxies and with the large-scale structure of the universe as a whole. Astronomers are concerned not only with discovering what is “out there” but also with why celestial bodies are as they are and behave as they do, with the forces that govern the behavior of matter and radiation in the cosmos, and with the origin, evolution, future, and ultimate fate of the universe and all that it contains.

Astronomy is primarily an observational rather than an experimental, or laboratory, science. Whereas a physicist or chemist can set up an experiment in the laboratory under known conditions, change the conditions, and measure the outcome, an astronomer cannot, for example, compress a star to see what happens. Unlike in our immediate neighborhood, where spacecraft can investigate directly the properties of planets, moons, and interplanetary space, astronomers have to rely on receiving information in the form of radiation from distant objects – observing without influencing or touching what they observe. They use their observations to develop hypotheses and theories and then carry out further observations to test the validity of those theories.

Astronomers draw on many other sciences, notably physics, chemistry, and mathematics, but also geology, biology, and a variety of other subjects, in order to analyze, interpret, and understand their observations.