AST 118 Lecture Notes - Spiral Galaxy, Right Ascension, Great Circle
Document Summary
The scientific method: observation, experimentation, logic, skepticism. Model first seems to explain hypothesis: after testing if it correctly explains observations and predicts future observations, it is a theory, model must always agree with the hypothesis. In astronomy: start with observations, then turn them into a theory. The night sky and celestial sphere, chapter 1. 5, 2. 4. Astronomy; the study of the universe: oldest of all the sciences. Month one orbit of moon around the earth. Year one orbit of the earth around the sun. In ancient cultures, astronomy was thought to influence peoples lives. Modern astronomy is a pure science: laws of physics as we know them are valid throughout the universe, astronomy has no experimentation, only observation. How many stars can we see on a clear night with no moons and no street lights: full sphere: 6,000, hemisphere: 3,000, extinction near horizon: 2,000. Stars are not all the same distance from us.
