1 .		The Theory of Solar System Formation. The discussion in this chapter cites the recent modifications to our theory of solar system formation as an example of how science progresses. Do you agree that this example illustrates the hallmarks of science that we discussed in Chapter 2? Why or why not?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
2 .		The Copernican Principle and Rare Earth. The Copernican revolution taught us that our planet was not the center of the universe, as had been generally believed before that time. Taking this lesson to heart, since that time we have generally assumed that our planet is not "central" or "special" in any way but rather that we are on a fairly typical planet in a fairly typical place in the universe. This principle, often called the Copernican Principle or the Principle of Mediocrity, has been borne out many times since. For example, we have learned that we are not near the center of our galaxy and that the universe has no center at all. Do you consider this principle to be in conflict with the rare Earth hypothesis? If so, does this make the rare Earth hypothesis any less scientific? Defend your opinions.   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
3 .		What Is a Planet? When asked what the difference is between an asteroid and a planet, one astronomer answered with "If it's round, it's a planet." Why are the larger members of the solar system---all the planets, many of the moons, and some large asteroids---round? Should "roundness" be included in the criteria for defining a planet? Explain.   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.