1. Express in your own words the nature of scientific theory, and explain the differences between scientific theory, hypothesis, and faith.
2. We have noted that the planets appear to travel across the sky along the same strip. What does this observation tell us about the orbits of the planet around the Sun?
3. Suppose two objects in the sky have the same angular diameter (they appear to be the same size). What does this tell us about the actual sizes of the two objects? Explain.
4. Explain why positions of objects in the sky are measured in angles rather than in units of linear distance such as miles or kilometers.
5. Explain why it is necessary to have observatories in both the Southern and Northern Hemispheres. At what latitude is the largest possible fraction of the sky visible?
6. If galaxies formed 10 billion years ago, how far away must we look in order to see the universe at a time before any galaxies existed?