Chapter 45, Satellite Systems and Rings Video Solutions, Pathways to Astronomy

Problem 1

During a close flyby, the Cassini spacecraft yielded a new estimate of the mass of Enceladus of $1.08 \times 10^{20} \mathrm{kg}$. Given that Enceladus's diameter is $499 \mathrm{km}$, calculate its density. The larger satellite Tethys has a density of about $1.0 \mathrm{kg} / \mathrm{L}$. What does this density suggest about Enceladus's composition relative to Tethys's? How might this account for Enceladus's unusual surface features?

Laurent Bergeron

Numerade Educator

01:54

Problem 2

The Earth's Moon experiences tidal forces that are gradually expanding its orbit by a few centimeters per year (Unit 37). Explain how a moon orbiting faster than its planet rotates will experience a "tidal drag" that causes its orbit to shrink.

Rodger Claar

Numerade Educator

05:02

Problem 3

Scientists have offered two different hypotheses to explain Miranda's tortured-looking surface. It may have resulted from tectonic activity, or it may have sustained a giant impact. If you could send a probe to Miranda, what kind of tests would you make to try to gather evidence that would help choose between these two hypotheses?

Teresa Kelly

Numerade Educator

03:52

Problem 4

Figure 45.11 shows a pair of shepherd moons and the ring between them. Assume that the moons and ring particles are orbiting counterclockwise in the image.
a. Because Kepler's laws apply, compare the relative speeds of the moons and ring particles.
b. If a passing moon boosts the speed of a ring particle, what will happen to the size of the ring particle's orbit?
c. If a ring particle experiences a slowing of its speed when it passes a slower moon, what happens to the size of the ring particle's orbit?
d. Explain how two shepherding moons might drive ring particles into a narrow stream.

Keshav Singh

Numerade Educator

01:13

Problem 5

Examine Appendix Tables 5 and 7 to determine which moons orbit inside the Roche limit, for each of the giant planets. Make a list of these moons and discuss how it is possible for these moons to orbit there. Would you expect these moons to be spherical or irregular? Why?

Rodger Claar

Numerade Educator

03:53

Problem 6

Suppose a moon that was 100 kilometers in diameter broke up into particles just 1 millimeter in diameter.
a. What was the surface area of the moon before it broke up?
b. How many particles 1millimeter in diameter could be made from the moon?
c. What is the total surface area of all of the 1 -mm particles you found in part b?
d. What is the ratio of the surface area in part $c$ to the surface area in part a? Explain why this ratio also represents how much sunlight would be reflected by the particles versus the original moon.

Prabhu Ramji

Numerade Educator