Homework Assignment #2

Name:

Section number:

Date Due: Sept. 22

1. What feature(s) do Aristotle's and Ptolemy's models of the heavens have in common? Name one principal difference between them.

2. How does Copernicus's model of the heavens explain the apparent retrograde motions of the planets? How does his model account for the absence of stellar parallax?

3. Describe how one of Galileo's major telescopic discoveries supported the heliocentric model and refuted the Aristotelian-Ptolemaic model.

4. The Martian volcano Elysium Mons lies at a latitude of 25 degrees. A second volcano, Olympus Mons, lies at a latitude of 19 degrees. The distance between the latitudes of the two volcanos is about 360 km. What is the radius of Mars in km?

5. Mercury's greatest elongation from the sun averages 23 degrees. Using simple geometry (see Fig. 1.26A), calculate Mercury's average distance from the sun, in Astronomical Units (AU).

6. The asteroid (1) Ceres has an average distance from the sun of 2.77 AU. Calculate its orbital period in years.