Introduction to Astronomy and Cosmology
Chapter One
Astronomy, an Observational Science
1.1 Introduction
Astronomy is probably the oldest of all the sciences. It differs from virtually all
other science disciplines in that it is not possible to carry out experimental tests
in the laboratory. Instead, the astronomer can only observe what he sees in the
Universe and see if his observations fit the theories that have been put forward.
Astronomers do, however, have one great advantage: in the Universe, there exist
extreme states of matter which would be impossible to create here on Earth. This
allows astronomers to make tests of key theories, such as Albert Einstein's General
Theory of Relativity. In this first chapter, we will see how two precise sets of observations,
made with very simple instruments in the sixteenth century, were able
to lead to a significant understanding of our Solar System. In turn, these helped
in the formulation of Newton's Theory of Gravity and subsequently Einstein's
General Theory of Relativity - a theory of gravity which underpins the whole of
modern cosmology. In order that these ... read full excerpt from Introduction to Astronomy and Cosmology ebook
