STARS AND THE UNIVERSE


Homework 1

due Friday February 12th



  1. Use the method illustrated in AT Figure 2.11 to draw an ellipse representing Pluto's orbit, using a scale such that 1 cm represents 5 a.u. Use the orbital parameters given in Table 2.1. First compute and state (i) the length of string needed between the thumbtacks; and (ii) the required separation of the thumbtacks. Then try the drawing on a separate piece of paper.

  2. Which observations of Galileo helped refute the views of Aristotle and confirm those of Copernicus?

  3. Ganymede is the largest of the four large moons of Jupiter that were discovered by Galileo. The radius of Ganymede's orbit is 1,070,000 km, and Ganymede's orbital period is 7.15 days. Use the modified form of Kepler's Third Law (c.f. Section 2.7 in AT) to compute the mass of Jupiter. (You may assume that it is very much larger than that of Ganymede.) Give your answer both in solar masses and in grams.