Astro 120  Fall 2005
Essay Question for Exam 1

You will be asked to answer this question during Exam 1 on Thursday, September 29. Please think about how you will answer this question before the exam, and write your answer during the exam time.

PART II: ESSAY (20 points): Answer the question on this sheet front and (if needed) back only.

Name: _________________________        Section Number:________

In 1543, Copernicus published his book (that nobody read) that promoted the idea that the Sun, not the Earth, was the center of our Solar System. Decades later, Tycho Brahe and then Johannas Kepler became two very important figures in the "Copernicann Revolution" yet their views of our solar system could not have been more different. Tycho firmly believed in a geocentric solar system while Kepler finally revealed the "modern" view of the heliocentric scheme.

In a one-page essay, discuss the changing view of our Solar System focusing on the roles of Tycho Brahe and Johannes Kepler. In your essay, begin by explaining why Tycho rejected the Copernican system. Pick up the story with Kepler emphasizing his connection with Tycho, and how he improved upon the Copernican model. In your essay, you should address the following questions: What different assumptions did Kepler make? What did he have to work with that Copernicus did not? How did that help?