To understand how evidence allows us to distinguish between alternate possible models of the solar system. Imagine that you did not know whether Earth is the center of the solar system (as the Greeks assumed) or just one planet going around the Sun. In this activity, you will consider a set of observations, some real and some not real, that could help you distinguish between the Greek Earth-centered model and our modern Sun-centered model. Note that, in the Greek Earth-centered model, the planets Mercury and Venus lie between Earth and the Sun, while all other planets orbit Earth beyond the orbit of the Sun.
Consider the following observations. Classify each observation based on whether it is a real observation (a true statement of something we can actually see from Earth) or one that is not real (a statement of something that does not really occur as seen from Earth).
1) Mercury goes through a full cycle of phases.
2) Moon rises in east, sets in west.
3) stars circle daily around north or south celestial pole.
4) positions of nearby stars shift slightly back & forth each year.
5) a distant galaxy rises in east, sets in west each day.
6) a planet beyond Saturn rises in west, sets in east.
7) we sometimes see a crescent Jupiter.