Astronomy is one of the oldest natural sciences, with practices dating back thousands of years. For a long time astronomers were mainly concerned with charting and predicting the motions of objects they could see with the unaided eye. Advances in optical technology brought in telescopes and extended the range astronomers could see, giving them much better clarity on what they were observing. They were still limited by what their own eyes could percieve however. As electromagnetic theory developed, scientists became aware that the visible light we observe from objects is only a tiny portion of a much larger electromagnetic spectrum. As the technology to detect and analyze more areas of this spectrum were created, astronomy was able to expand into what would become modern astrophysics, with the terms astronomy and astrophysics becoming mostly interchangeable. Today, the field of astrophysics covers a large variety of research areas thanks to the application of modern physics and advanced observing techniques. If you are interested in learning the field on a more technical level, check out the self-teaching guide.