Astronomy Ch03.7: Process of Science Task: Earth-Centered vs. Sun-Centered Models

Part B Consider again the set of observations from Part A. This time, classify each observation according to whether it is consistent with only the Earth-centered model, only the Sun-centered model, both models, or neither model. (Note that an observation is "consistent" with a model if that model offers a simple explanation for the observation.) [Earth-centered only] - a planet beyond Saturn rises in west, sets in east [Sun-centered only] - Mercury goes through a full cycle of phases - positions of nearby stars shift slightly back and forth each year [Both models] - stars circle daily around north or south celestial pole - moon rises in east, sets in west each day - a distant galaxy rises in east, sets in west each day [Neither model] - we sometimes see a crescent Jupiter

Now continue to the follow-up questions to check that you understand why the observations fall into these categories.

Earth rotates from west to east, so objects in the sky must appear to go across our sky from east to west. - is farther than Earth from the Sun

An object must come between Earth and the Sun for us to see it in a crescent phase, which is why we see crescents only for Mercury, Venus, and the Moon.

Part A 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). [Real:true statements] - Mercury goes through a full cycle of phases - Moon rises in east, sets in west each day - stars circle daily around north or south celestial pole - positions of nearby stars shift slightly back and forth each year - a distance galaxy rises in east, sets in west each day [Not real:false statements] - we sometimes see a crescent Jupiter - a planet beyond Saturn rises in west, sets in east

Before you continue to Part B, think about why each of the preceding observations are real or not real.

Part C Consider the hypothetical observation "a planet beyond Saturn rises in west, sets in east." This observation is not consistent with a Sun-centered model, because in this model __________. - the rise and set of all objects depend only on Earth's rotation

Earth rotates from west to east, so objects in the sky must appear to go across our sky from east to west.