We browse through it and fill some blanks with details in following Chapters. We measure an unknown quantity by comparison with a known quantity. To get distances and sizes in astronomy we use angle measurements and a baseline . We use Scientific Reasoning to test our view of the world and to develop new measurement methods.
Earth goes around sun.
Earth rotates on its axis. Prediction Coriolis force apparent force as earth rotates iii. First proof of earth's rotation. To understand the universe and its contents we build models of what is going on.